Circuit writer

• US 5,099,090 A
• Filed: 01/11/1990
• Issued: 03/24/1992
• Est. Priority Date: 05/11/1988
• Status: Expired due to Fees

• Current Assignee: Sophia Systems Co., Ltd. (Kuroda Electric Company Limited)
• Original Assignee: Ariel Electronics, Inc.
• Inventors: Horne, Stephen J., Bates, Kenneth N., DeBardi, Gary A., Erley, Robert B., Patel, Manu C., Jacobs, Thomas L., Hamade, Ramzi F., Rose, John E., Neogi, Amar N., Allan, G. Graham, Warden, David P., Schlosser, Mark S.
• Primary Examiner(s): Nimmo, Morris H.
• Application Number:
  US07/460,980
• Time in Patent Office: 803 Days
• Field of Search: 174/250, 174/257, 174/261, 29/846, 106/20, 252/512, 252/514, 264/40.7, 264/104, 264/254, 425/113, 425/114, 425/133.1, 425/135, 425/145, 425/150, 425/378.1, 425/376.1, 425/381, 425/461, 118/410, 118/411, 118/412, 118/415, 523/457-459, 524/401, 524/439, 524/871
• US Class Current: 174/257
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 2201/09581 Applying an insulating coating on the walls of holes
• CPC Class Codes: H05K 2201/09827 Tapered, e.g. tapered hole, via or groove bevelled, chamferred or tapered edge H05K2201/09154
• CPC Class Codes: H05K 2201/0989 Coating free areas, e.g. areas other than pads or lands free of solder resist
• CPC Class Codes: H05K 2203/0126 Dispenser, e.g. for solder paste, for supplying conductive paste for screen printing or for filling holes
• CPC Class Codes: H05K 2203/0763 Treating individual holes or single row of holes, e.g. by nozzle
• CPC Class Codes: H05K 3/0091 Apparatus for coating printed circuits using liquid non-metallic coating compositions
• CPC Class Codes: H05K 3/1241 by ink-jet printing or drawing by dispensing
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates
• CPC Class Codes: H05K 3/4644 by building the multilayer layer by layer, i.e. build-up multilayer circuits making via holes in the insulating layers H05K3/0011; special circuit boards as base or core whereon the multilayer is built H05K3/4602
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

An apparatus and method are disclosed for preparing electrically conductive traces on a circuit board using an additive technology. The traces are directly written in a serial process with each trace being able to be individually insulated. The apparatus includes an extrusion element for extruding a first material and a stage. The stage is for holding the extrusion element and the circuit board in relative proximity and for producing relative motion between the extrusion element and the circuit board in order to extrude the first material onto the surface of the circuit board along preselected paths to produce the electrically conductive traces. According to the method of invention, a first polymerizable material is extruded onto a circuit substrate support along preselected paths to form traces, and the first polymerizable material is polymerized, the first polymerizable material being conductive after polymerization. A circuit board for holding electrical components is disclosed which includes a circuit substrate support and a plurality of electrically conductive traces. The traces are adhered to the circuit substrate support between locations for the electrical components, the traces being formed of a polymer thick film by extrusion from an orifice onto the support along paths defining the location of the traces. Several embodiments of extrusion systems are described as are systems for milling and drilling boards to provide new manufactures of circuit boards.

Claims

1. An apparatus for forming traces between pads on a printed circuit board comprising:

first extrusion means for extruding a first extrudable material that is conductive after curing to form conductive traces;

carriage means for carrying said first extrusion means;

a write tip associated with said first extrusion means, for ejecting and forming the first extrudable material onto the printed circuit board;

a first guide means for constraining the movement of said carriage means in a first linear direction;

a base frame for mounting said first guide means;

a write table for positioning and holding said printed circuit board during forming of said traces, said write table mounted to said base frame;

means for holding said printed circuit board against said write table during forming of traces;

second guide means for constraining the movement of said carriage means in a second linear direction orthogonal to said first direction;

third guide means for constraining the movement of said write tip orthogonal to said first and second directions;

first drive means for moving said carriage means along said second guide means;

second drive means for moving said carriage means along said second guide means;

third drive means for moving said write tip along said third guide means; and

computerized control means for controlling said first, second and third drive means, and for starting and stopping extrusion of material by said first extrusion means, thereby controlling the start point, end point, and the shape of traces extruded onto said printed circuit board.

2. An apparatus for forming traces as in claim 1 wherein said first guide means comprises:

a pair of substantially parallel rails;

first saddle means slidably mounted to one of said pair of rails;

second saddle means slidably mounted to the other of said pair of rails; and

said second guide means being fixedly attached to each of said first and said second saddle means such that said second guide means and said first and said second saddle means travel together along said pair of rails.

3. An apparatus for forming traces as in claim 2 wherein said parallel rails are smooth steel shafts and said first and second saddle means mount to said rails by linear shaft bearings.

4. An apparatus as in claim 1 wherein said means for holding said printed circuit board against said write table comprises vacuum means for creating a pressure differential to urge a printed circuit board against said write table.

5. An apparatus for forming traces as in claim 2 wherein said second guide means comprises a pair of substantially parallel rails, said carriage means spans said pair of rails, and said carriage means is slidably mounted to each of said pair of rails.

6. An apparatus as in claim 5 wherein said rails of said second guide means are smooth steel shafts and said carriage means mounts to said rails by linear shaft bearings.

7. An apparatus as in claim 1 further comprising second extrusion means for extruding a second extrudable material over said first extrudable material, said second extrudable material being an electrically insulative material.

8. An apparatus as in claim 5 further comprising:

four frame posts arranged in a substantially rectangular pattern;

a plurality of cable pulleys attached to said frame posts, to said first and second saddle means, and to said carriage means;

at least one adjustable cable anchor at each of said four frame posts;

wherein said first and second drive means each comprises a system of cables arranged through said plurality of pulleys and anchored at said adjustable cable anchors such that, operating said first and second drive means moves said carriage in a horizontal plane with two degrees of freedom.

9. An apparatus as in claim 8 wherein said first drive means comprises:

a first electric drive motor mounted to said base frame;

a first cable drum attached to and turned by said first electric drive motor;

a first cable and a second cable wrapped on said cable drum in opposite rotary directions and extending from said cable drum toward one side of said apparatus; and

a third cable and a fourth cable wrapped on said cable drum in opposite rotary directions and extending from said cable drum toward the opposite side of said apparatus.

10. An apparatus as in claim 9 wherein;

said first cable passes around said cable pulleys attached to a first of said frame posts and said pulleys attached to said first saddle means and anchors to a first of said adjustable cable anchors attached to said first frame post;

said second cable passes around said cable pulleys attached to a second of said frame posts and said cable pulleys attached to said first saddle means and anchors to a second of said adjustable cable anchors attached to said second frame post;

said third cable passes around said cable pulleys attached to a third of said frame posts and said cable pulleys attached to said second saddle means and anchors to a third of said adjustable cable anchors attached to said third frame post; and

said fourth cable passes around said cable pulleys attached to a fourth of said frame posts and said cable pulleys attached to said second saddle means and anchors to a fourth of said adjustable cable anchors attached to said fourth frame post;

such that rotation of said first cable drum in one rotary direction urges said first and second saddle means together along said first guide means in one direction, and rotation of said first cable drum in the opposite rotary direction urges said first and second saddle means together along said first guide means in the opposite direction.

11. An apparatus as in claim 10 wherein said adjustable anchors are adjusted to exert substantially equal tensile stress on each of said cables to avoid movement during operation due to strain of said cables.

12. An apparatus as in claim 10 wherein said first and said third cables are wrapped side by side from one end of said first cable drum and said second and said fourth cables are wrapped side by side from the opposite end of said first cable drum, so that as said first and said second saddle means are moved along said first guide means, the angles formed by each of said cables with the longitudinal axis of said first cable drum remain substantially the same, tending to equalize force exerted by each cable and friction drag experienced by each cable.

13. An apparatus as in claim 8 wherein said second drive means comprises:

a second electric drive motor mounted to said base frame;

a second cable drum attached to and turned by said second electric drive motor;

a first cable wrapped on said cable drum and extending toward one side of said apparatus; and

a second cable wrapped in the same rotary direction as said first cable on said second cable drum and extending toward the other side of said apparatus.

14. An apparatus as in claim 13 wherein:

said first cable passes around one of said cable pulleys attached to a first of said frame posts, around one of said pulleys attached to said first saddle means, around one of said pulleys attached to said carriage means, around another of said pulleys attached to said first saddle means, and anchors to one of said adjustable anchors attached to a second of said frame posts; and

said second cable passes around one of said cable pulleys attached to a third of said frame posts, around one of said pulleys attached to said second saddle means, around one of said pulleys attached to said carriage means, around another of said pulleys attached to said second saddle means, and anchors to one of said adjustable anchors attached to a fourth of said frame posts;

such that rotation of said second cable drum in one rotary direction urges said carriage means along said second guide means in one direction and rotation of said second cable drum in the opposite rotary direction urges said carriage along said second guide means in the opposite direction, and operation of said first drive means does not move said carriage along said second guide means.

15. An apparatus as in claim 14 wherein said cables are wrapped side by side from one end of said second cable drum so that as said carriage is moved along said first guide means, the angles formed by each of said cables with the longitudinal axis of said second cable drum remain substantially the same, tending to equalize force exerted by each cable and friction drag experienced by each cable.

16. An apparatus as in claim 1 wherein said first extrusion means comprises:

reservoir means for containing a supply of said first extrudable material;

gas supply means connected to said reservoir means for applying pressure to said first extrudable material in said reservoir means to extrude said first extrudable material from said extrusion means;

;

flexible tube connecting means between said reservoir means and said write tip; and

valve means in said flexible tube connecting means for stopping the flow of said first extrudable material between said reservoir means and said write tip.

17. An apparatus as in claim 16 wherein said gas supply means further comprises pressure control means for controlling said pressure thereby controlling the rate of extrusion of said first extrudable material from said first extrusion means, and said pressure control means is controllable by said computerized control means in response to programmed information.

18. An apparatus as in claim 16 wherein said valve means comprises:

a rotary valve having an inlet, a flow-through passage, and a side passage from said flow-through passage;

an third electric motor for rotating said rotary valve; and

an overflow container connected to said side outlet;

such that in one position said flow-through passage passes said first extrudable material substantially unimpeded through said rotary valve to said write tip, said first extrudable material being urged along by said pressure;

such that a small rotation of said rotary valve by said third drive motor completely disconnects said flow-through passage from said reservoir means, quickly stopping flow of extrudable material to said write-tip;

and such that a larger rotation connects said reservoir means through said side passage with said overflow container, relieving pressure across said valve from said reservoir means to said write tip, completely removing any tendency for extrudable material to continue to be urged through said write tip.

19. An apparatus as in claim 16 further comprising:

a fourth electric drive motor for raising and lowering said write tip, said fourth electric motor mounted to said carriage;

slide means engaged in said third guide means and fastened to said write tip so that said slide means and said write tip move vertically together in said guide means;

a shaft driven by said fourth electric motor;

a thin tongue of material wrapped on said shaft and fastened to said slide means such that rotation of said shaft by said fourth electric motor causes said slide with said write tip to move in the z-direction in said third guide means; and

said fourth electric motor being controllable by said computerized control means so that said write tip may be moved in the z-direction in response to preselected instructions.

20. An apparatus as in claim 16 further comprising an electrically powered heater block connected to said write tip, said heater block controllable by said computerized control means in response to preselected instructions, for controlling the temperature of said extrudable material during extrusion, thereby exercising control over such heat responsive characteristics as thixotropy and viscosity.

21. An apparatus as in claim 16 wherein said write tip further comprises:

a fitting connected to said flexible tube connecting means; and

hypodermic-type tubing engaged in said fitting.

22. An apparatus as in claim 21 wherein said hypodermic-type tubing has an outside bevel making the outside diameter of said tubing smaller at the outlet end, where extrudable material exits onto said printed circuit board, than the nominal outside diameter of said tubing, thereby controlling the width of the trace extruded to be less than the width would be without said bevel.

23. An apparatus as in claim 21 wherein said hypodermic-type tubing has an inside bevel making the inside diameter of said tubing larger at the outlet end, where extrudable material exits onto said printed circuit board, than the nominal inside diameter of said tubing, thereby controlling the width of the trace extruded by said tubing to be more than the width would be without said bevel.

24. An apparatus as in claim 1 wherein said write table is pivotally mounted to said base frame such that the pivot axis is substantially in the z-direction, and further comprising:

pivot drive means for rotating said write table about said pivot axis, said pivot drive means controllable by said computerized control means; and

video camera means mounted to said carriage, focusable onto said circuit board, said video camera means supplying an image with alignment means for use by an operator to align a printed circuit board prior to traces being written.

25. Apparatus for producing electrically conductive traces on a circuit board comprising:

extrusion means for extruding a material that is electrically conductive after curing, hereinafter called the electrically conductive material;

said extrusion means comprising an extrusion housing in which extrudable polymer is contained, means for applying a force to said extrudable polymer from said housing and onto a circuit board, means for monitoring rate of extrusion information, and first control means for controlling the application of force in response to said rate of extrusion information supplied by said monitoring means;

stage means for holding said extrusion means and said circuit board in relative proximity and for producing relative motion of said extrusion means and said circuit board; and

second control means for controlling said extrusion means and said stage means to cause said electrically conductive material to be extruded onto a surface of said circuit board along preselected paths to produce said traces.

26. Apparatus as in claim 25 further comprising:

second extrusion means for extruding an electrically insulating material;

wherein

said stage means comprises means for holding said second extrusion means in proximity of said circuit board and for moving said second extrusion means relative to said circuit board, and wherein said second extrusion means further comprises;

means for controlling said second extrusion means to cause said electrically insulating material to be extruded onto said surface of said circuit board along said traces formed by said first extrusion means to produce electrically conductive traces that are insulated.

27. Apparatus as in claim 26 wherein said extrusion means comprises first heating means for heating the electrically conductive material.

28. Apparatus as in claim 27 wherein said second extrusion means comprises second heating means for heating the electrically insulative material.

29. Apparatus as in claim 25 wherein said extrusion means comprises first heating means for heating the electrically conductive material.

30. Apparatus as in claim 25 further comprising:

second extrusion means for extruding an electrically insulating material;

said stage means comprising means for holding said second extrusion means and the circuit board in relative proximity and for producing relative motion of said extrusion means and the circuit board;

said control means for controlling said second extrusion means and said stage means to cause said electrically insulating material to be extruded onto the surface of the circuit board at a plurality of points along said traces produced by said first extrusion means to produce electrically conductive traces that are insulated at said plurality of points.

31. Apparatus for producing traces on a circuit board comprising:

extrusion means for extruding a first extrudable polymeric material;

said extrusion means comprising an extrusion housing in which extrudable polymer is contained, means for applying a force to said extrudable polymer from said housing and onto a circuit board, means for monitoring rate of extrusion information, and control means for controlling the application of force via said force applying means in response to said rate of extrusion information supplied by said monitoring means;

stage means for holding said extrusion means and a circuit board in relative proximity and for producing relative motion between said extrusion means and said circuit board to extrude said first material onto a surface of said circuit board along preselected paths.

32. A method of producing electrically conductive traces on a circuit substrate support comprising the steps of:

extruding a first polymerizable material onto a circuit substrate support along preselected paths to form traces;

polymerizing said first polymerizable material, said first polymerizable material being conductive after polymerization;

applying a second polymerizable material over said support at a plurality of points along said preselected paths overlying said first polymerizable material; and

polymerizing said second polymerizable material, said second polymerizable material being electrically insulative after polymerization.

33. The method of claim 32 wherein said steps of polymerizing said first and second polymerizable materials overlap in time.

34. The method of claim 33 wherein the steps of polymerizing said first and second polymerizable materials comprise heating said support after said first and second polymerizable materials have been applied thereto.

35. The method of claim 32 wherein the steps of polymerizing said first and second polymerizable materials comprises providing an environment for polymerization to occur and waiting till polymerization occurs.

36. The method of claim 32 further comprising the step of applying to said support a third material along preselected paths overlying said first polymerizable material and intersecting said traces formed by said first polymerizable material at least a subset of said points that are insulated by said second polymerizable material, wherein said third material is electrically conductive after being applied to said support.

37. The method of claim 36 wherein said third material is the same as said first polymerizable material, and the step of applying said third material includes polymerizing said third material.

38. The method of claim 37 wherein the steps of polymerizing said first polymerizable material, said second polymerizable material, and said third material overlap in time.

39. A circuit board for holding electrical components comprising:

a circuit substrate support;

a plurality of electrically conductive traces adhered to said circuit substrate support between locations for electrical components, said traces being formed of a polymer thick film by extrusion from an orifice onto said support along paths defining the location of said traces wherein said traces are coated with an electrically insulating material formed by extrusion of said insulating material along said paths.

40. A circuit board as in claim 39 wherein said traces have a maximum thickness that is at least 25% of their minimum width.

41. A circuit board as in claim 39 wherein said traces have a maximum thickness at one or more locations of at least 50% of the minimum width of said traces.

42. A method of forming a circuit of insulated conductive traces on a substrate, the method comprising the steps of:

(a) calibrating a stage so that positions on a substrate correspond to positions pre-programmed into a trace routing engine, the trace routing engine containing a programmed representation of the circuit;

(b) extruding a trace onto said substrate by a first extrusion means under programmed control of the trace routing engine, said trace consisting of a first material;

(c) hardening said trace;

(d) layering a second material onto said hardened trace, the second material encapsulating said hardened trace;

(e) hardening said second material;

(f) repeating steps (b) through (e) until a cricuit determined by the trace routing engine is complete; and

(g) curing the first and second materials to form the circuit of insulated conductive traces.

43. The method of claim 42 wherein said step of layering includes extruding said second material onto said hardened trace by a second extrusion means under programmed control of said trace routing engine.

44. The method of claim 43 wherein said first material and said second material are pseudoplastic.

45. The method of claim 43 wherein said step of layering further includes forming an interfacial layer between said second material and said first material, the interfacial layer consisting of a hydrophobic polymer.

46. The method of claim 45 wherein said first material is a polymer solution comprising an epoxy resin or prepolymer, a diamine or polyamine hardener, a first high evaporation rate solvent, and conductive particulates, and wherein said second material is a polymer solution comprising an aryl dicyanate, a second high evaporation rate solvent, a hydroxyl accelerator, and a metal catalyst.

47. The method of claim 46 wherein said step of hardening said trace includes evaporating said first high evaporation rate solvent from said trace, and wherein said step of hardening said second material includes evaporating said second high evaporation rate solvent from said second material.

48. The method of claim 47 wherein said first extrusion means extrudes said first material through a write tip having a width in the range of 3 to 20 mils.

49. An insulated conductive trace on a surface of a substrate, the insulated conductive trace comprising:

a core consisting of an extruded conductive polymer thick film, the core having a width in the range of 3 to 20 mils and a resistivity in the range of 0.1 to 0.6 ohms per inch;

a sheath consisting of an extruded insulative polymer thick film, the sheath encapsulating the core and binding the core to said surface of said substrate; and

an interfacial layer between the core and the sheath, the interfacial layer consisting of an impermeable hydrophobic polymer.

50. The insulated conductive trace of claim 49 wherein said conductive polymer thick film comprises a crosslinked epoxy polymer filled with conductive particulates, the crosslinked epoxy polymer being crosslinked by a diamine or polyamine hardener, and wherein said insulative polymer thick film comprises a polycyanurate.

51. The insulated conductive trace of claim 50 wherein said conductive polymer thick film further comprises 75 to 90 percent by weight conductive particulates, and wherein said conductive particulates are silver.

52. A device for extruding an extrudable material comprising:

a storage volume for storing a quantity of an extrudable material;

a write tip with an opening to said storage volume, said write tip for ejecting and forming said extrudable material;

a fill passage connecting to said storage volume for supplying said extrudable material to said storage volume;

a valve passage with an opening into said fill passage;

a valve piston in said said valve passage urged by a spring to tend to close said opening into said fill passage;

a supply port opening into said valve passage such that said extrudable material under pressure introduced to said supply port moved said valve piston against said spring to open said valve passage to said fill passage allowing said extrudable material to flow from said supply port through said fill passage into said storage volume; and

a pressure port into said storage volume for introducing a gas under pressure to cause said extrudable material to extrude from said write tip.

53. A device as in claim 52 further comprising:

a metering piston in said storage volume such that as said extrudable material is extruded from said storage volume, said metering piston moves in said storage volume; and

piston sensing means for sensing the position of said piston in said storage volume to determine the relative fill level of said storage volume and the rate of extrusion of said extrudable material from said storage volume.

54. A device as in claim 53 wherein said metering piston is made of magnetically permeable material and said sensing means comprises an LVDT coil for sensing the position and relative movement of said piston.

55. A device as in claim 52 wherein said valve passage and said fill passage are colinear and said valve piston comprises:

a first portion having a first diameter fitting closely within said valve passage; and

a second portion having a second diameter smaller than said first diameter fitting closely within said fill passage;

said second portion having a connecting passage starting from the end of said second portion away from said first portion, proceeding toward said first portion, and turning and opening through the outer diameter wall of said second portion, such that said connecting passage is closed when said second portion is fully inserted into said fill passage, urged by said spring, and said connecting passage forms an open passageway from said valve passage to said fill passage when said valve piston is urged against said spring, partially withdrawing said second portion from said fill passage.

56. A device as in claim 52 further comprising:

a modular supply reservoir connecting to said supply port for supplying a fixed quantity of said extrudable material for supply to said storage volume of said device, said supply reservoir having a pressure port for supplying gas under pressure to urge said extrudable material from said modular supply reservoir.

57. A device as in claim 56 wherein said modular supply reservoir further comprises a first quick-connect fitting for connecting to said supply port and a second quick connect fitting for connecting at said pressure port.

58. A device as in claim 56 further comprising valve means connecting to said pressure port for supplying gas under pressure to and for venting of said supply reservoir.

59. A device as in claim 52 further comprising gas valve means connecting to said pressure port and to said storage volume for supplying gas under pressure to and venting of said storage volume.

60. A device as in claim 52 further comprising said extrudable material being stored in said storage volume, wherein said extrudable material comprises a pseudoplastic material having a yield point that is sufficiently high to support the weight of said metering piston.

61. A circuit board for holding electrical components comprising:

a circuit substrate support having an electrically non-conductive surface;

a plurality of electrically conductive mounting pads on said non-conductive surface, said mounting pads being formed of an extruded polymer thick film;

a plurality of electrically conductive traces between and connecting to said mounting pads, said electrically conductive traces being formed of an extruded polymer thick film along paths defining the location of said traces, wherein said traces are covered with a coating of electrically insulating material formed by extrusion of said insulating material along said paths.

62. A circuit board as in claim 61 having a plurality of layers of electrically conductive traces, at least some layers having a plurality of said traces that cross over said traces from a previous layer, and are electrically connected to said pads without vias.

63. A method of building a precise geometric shape on a circuit board comprising:

extruding a polymerizable material on to board;

curing said polymerizable material;

machining portions of said material after polymerization to form said precise geometric shape.

64. A method of forming an electrical connection between two otherwise electrically isolated mounting pads, said pads having been constructed on a circuit substrate support having an electrically conductive clad layer over an electrically non-conductive support material by removing trenches through said clad layer to form said pads, comprising the steps of:

forming an insulative roadbed between mounting pads on a circuit substrate support by extruding insulative polymerizable thick film from an orifice, said roadbed overlying a conductive clad layer between said mounting pads;

forming a conductive trace between said mounting pads by extruding polymerizable thick film between said mounting pads, said conductive trace touching each of said conductive pads and following and overlying said insulative roadbed, said conductive trace being narrower in breadth than said insulative roadbed;

polymerizing said polymerizable thick films, said thick film for said conductive trace being electrically conductive after polymerization; and

extruding an insulative cover of polymerizable thick film over said extruded conductive trace before said polymerization step, said insulative cover together with said insulative roadbed encapsulating said conductive trace.

65. A method of forming a conductive trace between two otherwise electrically isolated mounting pads as in claim 64 comprising the step of:

extruding an insulative cover of polymerizable thick film over said extruded conductive trace before said polymerization step, said insulative cover together with said insulative roadbed encapsulating said conductive trace.

66. A circuit board for holding electrical components comprising:

a circuit substrate support having an electrically conductive clad surface layer over a non-conductive support material;

a plurality of conductive mounting pads on said non-conductive support material, said mounting pads being constructed by forming trenches through said electrically conductive clad surface layer to form said mounting pads;

a plurality of extruded electrical traces between said mounting pads, said electrical traces formed of polymerizable thick film material, which becomes conductive after polymerization, over insulative roadbeds of extruded insulative polymerizable thick film material between said mounting pads and

wherein said electrical traces are encapsulated in extruded insulative material along said roadbeds.

67. A circuit board for holding electrical components as in claim 66 having a plurality of layers of electrically conductive traces, at least some layers having a plurality of said traces that cross over said traces from a previous layer, and are electrically connected to said pads without vias.

68. A method of forming an electrical connection between two otherwise electrically isolated mounting pads, said mounting pads constructed on a circuit substrate support having an electrically conductive clad layer over an electrically non-conducting support material by forming trenches through said clad layer to form said pads, comprising the steps of:

forming a connection trench through an electrically conductive layer between trenches forming isolated mounting pads;

extruding a trace of polymerizable material from one of said electrically isolated mounting pads to the other of said isolated mounting pads, following the path of said connecting trench, said trace being of narrower width than the width of said connecting trench, such that said trace nowhere touches said clad layer except at said isolated mounting pads; and

polymerizing said polymerizable material, said polymerizable material being electrically conductive after polymerization.

69. A method of forming an electrical connection between two otherwise electrically isolated mounting pads as in claim 68 further comprising the steps of:

extruding a trace of insulative material over said trace of conductive material; and

polymerizing said trace of insulative material;

said trace of insulative material forming a protective covering over said trace of conductive material.

70. A method of forming an electrical connection between two otherwise electrically isolated mounting pads formed on a circuit substrate support comprising:

forming an electrically conductive clad layer over an electrically non-conducting support material and a non-conductive layer over said electrically conductive clad layer,

forming trenches through said clad layer and said non-conductive layer

filling said trenches with insulative materials by extruding insulative polymerizable thick film from an orifice into said trenches;

extruding a trace of a second polymerizable material, which becomes conductive after polymerizing, from one of said electrically isolated mounting pads to the other of said isolated mounting pads, said trace touching the conductive materials of each of said mounting pads and overlying said non-conductive layer between said mounting pads and said insulative material filling said trenches; and

polymerizing said polymerizable materials.

71. A method of forming an electrical connection between two otherwise isolated mounting pads as in claim 70 further comprising the steps of:

extruding an encapsulating trace of insulative material over said trace of conductive material; and

polymerizing said encapsulating trace of insulative material.

72. A circuit board for holding electrical components comprising:

a circuit substrate support having an electrically conductive clad layer over a non-conductive support material and a non-conductive layer over said electrically conductive clad layer;

a plurality of conductive mounting pads on said non-conductive support material, said mounting pads being formed by forming trenches through said electrically conductive clad layer and said non-conductive layer and removing said non-conductive layer from said mounting pads, said trenches filled with an extruded insulative material; and

a plurality of extruded electrically conductive traces between and connecting to said mounting pads, said electrically conductive traces being formed of a polymer thick film and positioned along paths overlying said insulative material filling said trenches and overlying said non-conductive layer wherein said conductive traces are covered with a coating of extruded electrically insulative material onto said conductive traces along said paths.

73. A circuit board as in claim 72 having a plurality of layers of electrically conductive traces, at least some layers having a plurality of said traces that cross over said traces from a previous layer, and are electrically connected to said pads without vias.

74. A method of forming a mounting pad for registering and attaching leads of discrete devices on a circuit substrate support comprising the steps of:

extruding adjacent lines of polymerizable thick film materials onto a circuit substrate support, alternating lines of said material being insulative material and the other lines being material electrically conductive after polymerization, said insulative lines extending further above said circuit substrate support than said lines which are conductive after polymerization with said lines which are conductive after polymerization being substantially the width of said leads of discrete devices, such that the spaces between said insulative lines become registration trenches for said loads of said discrete devices; and

polymerizing said extruded lines of material.

75. A method of forming a mounting pad for registering and attaching leads of discrete devices as in claim 74 further comprising the step of extruding a line of insulative material crossing said adjacent lines of polymerizable thick film material at substantially a right angle prior to said polymerization step;

said crossing line being an additional constraint for registration of leads of said discrete devices.

76. A circuit board for holding electrical components comprising:

a circuit substrate support; and

a mounting pad for registering and attaching leads of discrete devices, said mounting pad formed of extruded adjacent lines of polymerizable thick film material on said circuit substrate support, alternating lines of said material being insulative material and the other lines being material electrically conductive after polymerization, said insulative lines extending further above said circuit substrate support than said lines which are conductive after polymerization with said lines which are conductive after polymerization being substantially the width of said leads of said discrete devices, such that the spaces between said insulative lines become registration trenches for said leads of said discrete devices.

77. A method of electrically connecting a conductive pad on one side of a circuit board having an inner conductive layer with a conductive pad on the other side of said circuit board without said electrical connection contacting said inner conductive layer, comprising the steps of:

drilling a first hole through a circuit board, said hole penetrating conductive pads on both sides of said board and penetrating an inner conductive layer;

extruding insulative polymerizable thick film material into said first hole from an orifice;

drilling a second hole through said insulative plug, said second hole leaving an annulus of insulative material within said first hole;

extruding a second polymerizable thick film material, said material being conductive after polymerization, into said second hole from an orifice such that said second material overlaps said insulative material on each side of said circuit board making contact with each said conductive pad, said second material being electrically isolated from said inner conductive layer by said annulus of insulative material; and

polymerizing said second polymerizable thick film material forming an electrical connection between said pads, said second material being electrically isolated from said inner conductive layer.

78. A circuit board for holding electrical components comprising;

a circuit substrate support having an inner conductive layer and a conductive pad on each side;

a connection between said pads on opposite sides of said circuit board, said connection comprising;

an insulative plug formed in a first hole drilled through said circuit board, said first hole penetrating conductive pads on each side of said circuit board and penetrating said inner conductive layer;

said insulative plug formed of extruded insulative polymerizable material from an orifice into said first hole;

a second hole drilled through said insulative plug leaving an annulus of insulative material through said circuit board; and

a conductive trace through said second hole, said conductive trace formed of extruded polymerizable material which is conductive after polymerization through said second hole, making contact with said pads on opposite faces of said circuit board, said conductive trace isolated from said inner conductive layer by said annulus of insulative material.

79. A method of electrically connecting a conductive pad on one side of a circuit board having an inner conductive layer with a conductive pad on the other side of said circuit board without said electrical connection contacting said inner conductive layer, comprising the steps of:

forming a slot through a circuit board, said slot penetrating conductive pads on both faces of said circuit board and penetrating an inner conductive layer;

extruding a roadbed of insulative polymerizable thick film material along a portion of said slot from an orifice, said roadbed crossing said inner conductive layer;

extruding a first trace of polymerizable thick film material into said slot from an orifice, said polymerizable material being conductive after polymerization, said first trace of polymerizable material having a lesser width than said roadbed for insulative material and overlying said insulative roadbed such that said first trace does not touch said inner conductive layer, said first trace touching each of said conductive pads on opposite faces of said circuit board; and

polymerizing said polymerizable materials.

80. The method of claim 79 comprising the additional step of extruding a covering trace of insulative polymerizable thick film material over said first trace, covering said first trace at the level of said inner conductive layer of said circuit board, prior to the step of polymerizing said polymerizable thick films.

81. The method of claim 80 wherein said covering trace of insulative polymerizable thick film material is extruded to fill said slot.

82. A circuit board for holding electrical components comprising:

a circuit substrate support having an inner conductive layer and a conductive pad on each side; and

a connection between said pad on opposite sides of said circuit board, said connection comprising;

a slot formed through said circuit board, said slot penetrating conductive pads on each side of said circuit board and penetrating said inner conductive layer;

an insulative roadbed in said slot, said insulative roadbed formed of extruded insulative polymerizable material, said insulative roadbed crossing said inner conductive layer of said circuit board; and

an extruded trace within said slot, said trace formed of extruded polymerizable material which is conductive after polymerization in said slot, said trace making contact with said pads on opposite sides of said circuit board, said trace being isolated from said inner conductive layer of said circuit board by said insulative roadbed.

83. A circuit board for holding electrical components as in claim 82 wherein said connection between said pads additionally comprises a covering trace of insulative material extruded from an orifice, said covering trace covering said trace at the level of said inner conductive layer of said circuit board.

84. A method of forming a mounting pad for registering and attaching leads of discrete devices on a circuit substrate support comprising the steps of:

extruding a pad of insulative polymerizable material onto an circuit substrate support;

polymerizing said polymerizable insulative material;

forming openings into said polymerized insulative pad, said openings for registering and mounting leads of electrical components;

extruding polymerizable material conductive after polymerization into said openings to form conductive mounting surfaces for said leads of said electrical components; and

polymerizing said conductive polymerizable material.

85. A polymer thick film extrusion device comprising;

an extrusion housing including a central passage in which extrudable polymer is contained;

a fill passage in said housing for allowing the passage of extrudable polymer from a polymer storage reservoir to said central passage;

means for forcing said extrudable polymer from said passage and onto a circuit board

means for monitoring the rate at which said extrudable polymer is extruded; and

control means for controlling the application of force applied via said force applying means responsive to said rate of extrusion information supplied by said monitoring means.

86. A polymer thick film extrusion device as in claim 85 wherein said means for forcing said extrudable polymer from said passage comprises a piston positioned within said central passage.

87. A polymer thick film extrusion device as in claim 86 wherein said piston is made from a magnetically permeable material and said monitoring means comprises an LVDT coil for sensing the position and rate of movement of said piston.

88. A polymer thick film extrusion device as in claim 86 wherein said control means comprises a gas control unit responsive to extrusion rate information supplied from said monitoring means, said gas control unit controlling gas pressure and gas flow rate from a pressurized gas source to said piston.

89. A polymer thick film extrusion device as in claim 85 further comprising valve means positioned adjacent said fill passage for controlling the flow of said extrudable polymer from said reservoir through said fill passage and into said central passage.

90. A polymer thick film extrusion device as in claim 89 wherein said valve means comprises a coil spring biasing said valve means toward a closed position.

91. A method of creating circuits on a circuit board comprising the steps of:

(1) extruding a first polymeric material onto a circuit board substrate along preselected paths to form traces, said polymeric material comprising a polymer solution which is conductive upon curing and which undergoes an increase in viscosity upon extrusion such that only negligible mechanical deformation takes place whenever crossover traces are laid over said traces; and

(2) prior to curing, extruding a second polymeric material onto said circuit substrate and over said traces.

92. A circuit board for holding electrical components comprising:

a circuit substrate support;

a plurality of electrically conductive pads attached to said support to which components are to be electrically connected

a plurality of electrically conductive traces adhered to said support and beginning and ending on top of said pads to form electrical pathways between said pads, said traces being formed by extrusion of a polymer thick film from an orifice, some of said plurality of traces crossing over a countable number of other traces;

said circuit board wherein said traces are coated with an electrically insulating material and formed by extrusion of said insulating material along said pathways.