OVERMOLDED CIRCUIT BOARD AND METHOD

• US 20090154182A1
• Filed: 12/12/2008
• Published: 06/18/2009
• Est. Priority Date: 12/12/2007
• Status: Active Grant

• Current Assignee: Fujitsu Limited, Innotec, Corp.
• Original Assignee: Innotec, Corp.
• Inventors: Mulder, Jason R., Veenstra, Thomas J., Fleischmann, Eric L.
• Granted Patent: US 8,230,575 B2
• Time in Patent Office: Days
• US Class Current: 362/487
• CPC Class Codes: B60Q 1/2696 Mounting of devices using LEDs
• CPC Class Codes: B60Q 3/217 Doors, e.g. door sills; Steps
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21V 19/001 the light sources being semiconductors devices, e.g. LEDs
• CPC Class Codes: H05K 1/142 Arrangements of planar printed circuit boards in the same plane, e.g. auxiliary printed circuit insert mounted in a main printed circuit
• CPC Class Codes: H05K 1/148 Arrangements of two or more hingeably connected rigid printed circuit boards, i.e. connected by flexible means
• CPC Class Codes: H05K 1/185 Components encapsulated in the insulating substrate of the printed circuit or incorporated in internal layers of a multilayer circuit semiconductor chips encapsulated by interconnect and support structures H01L23/5389, H01L24/00
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/0108 Transparent
• CPC Class Codes: H05K 2201/0129 Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
• CPC Class Codes: H05K 2201/09118 Moulded substrate
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 2201/10151 Sensor
• CPC Class Codes: H05K 2201/1034 Edge terminals, i.e. separate pieces of metal attached to the edge of the PCB tab H05K2201/0397
• CPC Class Codes: H05K 2201/10689 Leaded Integrated Circuit [IC] package, e.g. dual-in-line [DIL]
• CPC Class Codes: H05K 2203/1316 Moulded encapsulation of mounted components
• CPC Class Codes: H05K 2203/1476 Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
• CPC Class Codes: H05K 3/202 using self-supporting metal foil pattern
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: H05K 3/3405 Edge mounted components, e.g. terminals
• CPC Class Codes: H05K 5/064 : sealed by potting, e.g. waterproof resin poured in a rigid casing
• CPC Class Codes: Y10T 29/49002 : Electrical device making
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.

Abstract

An electrical device includes a circuit board having one or more electrical components mounted to the circuit board. At least a portion of the circuit board is encapsulated in a thermoplastic polymer material to encapsulate the electrical components. The device may be fabricated by at least partially shielding the electrical components with polymer material, followed by overmolding the polymer material with thermoplastic polymer material. The shielding material may comprise a pre-formed component, or it may comprise thermoplastic polymer material that is molded around the electrical components in a first molding step or “shot”.

Claims

1. A light assembly, comprising:

at least one circuit element comprising a board made of a non-conductive material and a plurality of conductive tracks disposed on at least one side of the board;

a plurality of conductive elements connected to the conductive tracks and extending away from the board;

at least one LED electrically connected to selected ones of the conductive tracks;

at least one electrical component electrically connected to the conductive tracks, wherein the one electrical component is selected from the group consisting of a resistor, a diode, a zener diode, a transistor, an integrated circuit, a capacitor, an inductor, a transient voltage suppressor, and a metal oxide varister; and

wherein the electrical component affects at least one of a voltage and an electrical current supplied to the LED;

a one-piece body comprising thermoplastic polymer material encasing the circuit element, the LED, and the one electrical component.

2. The light assembly of claim 1, wherein:

the thermoplastic polymer material includes a light-transmitting portion encapsulating the LED.

3. The light assembly of claim 1, wherein:

the conductive elements comprise sheet metal forming at least two cantilevered prongs having exposed metal protruding outside the thermoplastic polymer material, and wherein the thermoplastic polymer material includes a cavity having an open end to thereby form a receptacle around the prongs.

4. The light assembly of claim 3, including:

at least one electrical component mounted to the conductive elements at a location that is spaced apart from the board.

5. The light assembly of claim 1, wherein:

the polymer material forms a mounting flange having at least one opening therethrough that is configured to receive a fastener to mount the light assembly.

6. The light assembly of claim 1, wherein:

the conductive elements form positive and negative leads for connecting the light assembly to a power source;

the light assembly comprises a light for a motor vehicle, and wherein the one electrical component forms a circuit capable of supplying a desired electrical current to the LED when the positive and negative leads of the light assembly are connected to a 12 volt D.C. power source.

7. The light assembly of claim 6, wherein:

the thermoplastic polymer material comprises a translucent material.

8. The light assembly of claim 7, wherein:

all portions of the thermoplastic polymer material have substantially the same composition and color.

9. The light assembly of claim 1, wherein:

the thermoplastic polymer material includes convex outer surface portions that are aligned with the LEDs.

10. The light assembly of claim 1, wherein:

the circuit element comprises a printed circuit board.

11. The light assembly of claim 1, wherein:

the conductive elements comprise elongated flexible conductive members and flexible nonconductive material.

12. The light assembly of claim 11, wherein:

the flexible nonconductive material comprises a strip having a side surface and wherein the flexible conductive members are disposed on the side surface.

13. The light assembly of claim 1, wherein:

the conductive elements comprise a ribbon cable that is electrically connected to the conductive tracks of the circuit element.

14. The light assembly of claim 1, wherein:

the at least one circuit element comprises a plurality of spaced apart printed circuit boards that are electrically interconnected by conductive elements.

15. The light assembly of claim 14, wherein:

the one-piece body encases the plurality of printed circuit boards.

16. The light assembly of claim 15, wherein:

at least two of the printed circuit boards are substantially coplanar relative to each other.

17. The light assembly of claim 1, wherein:

the board defines a perimeter having opposite edge portions;

the conductive elements comprise a plurality of metal sections having generally flat surface portions;

the board is disposes on the flat surface portions of the conductive elements, and wherein portions of the conductive elements extend outwardly beyond the opposite edge portions.

18. The light assembly of claim 17, wherein:

the metal sections comprise sheet metal having substantially uniform thickness.

19. The light assembly of claim 6, wherein:

the one electrical component comprises a diode, and wherein the conductive tracks and the diode form a circuit that protects the one LED from damage in the event the positive and negative leads are incorrectly connected to negative and positive power sources, respectively.

20. A method of forming an electrical assembly, comprising:

providing a plurality of electrically conductive circuit elements;

providing at least one circuit element comprising a board having a side surface and a plurality of conductive tracks disposed on the side surface of the board;

securing at least one electrical component to at least a selected one of the conductive tracks;

positioning at least a portion of the circuit element and the electrical component in a first mold cavity having a first shape;

molding thermoplastic polymer material around the electrical component while it is in the first mold cavity to encapsulate the electrical component in a protective capsule of thermoplastic polymer material, the protective capsule having a first portion in contact with the conductive tracks and the board, the protective capsule having peripheral edge portions extending around at least a portion of the electrical component;

positioning at least a portion of the circuit element and the electrical component in a second mold cavity having a second shape that is substantially different than the first shape;

molding thermoplastic polymer material over at least a portion of the protective capsule.

21. The method of claim 20, wherein:

the side surface of the board defines a generally flat surface portion;

the peripheral edge portions of the protective capsule extend to the flat first surface portion and define a peripheral edge surface that is transverse to the flat surface portion.

22. The method of claim 21, wherein:

an exposed portion of the flat surface portion of the board is not covered by the protective capsule of polymer prior to positioning the circuit element and the electrical component in the second mold cavity; and

including;

molding thermoplastic polymer material over the exposed portion.

23. The method of claim 22, wherein:

the first mold cavity is shaped to mold thermoplastic polymer material over at least a substantial portion of the conductive circuit elements.

24. The method of claim 23, wherein:

the first mold cavity forms a groove around the electrical component that is generally C-shaped in plan view, and wherein the first mold cavity is shaped such that a bridge of thermoplastic polymer material extending from the additional polymer material to the protective capsule is formed in the first mold cavity.

25. The method of claim 24, wherein:

the groove defines a base surface, and at least a portion of the base surface comprises portions of the conductive tracks.

26. The method of claim 20, wherein:

the step of securing at least one electrical component includes soldering the electrical component to the conductive tracks.

27. The method of claim 20, wherein:

the one electrical component comprises an LED.

28. The method of claim 27, wherein:

at least one additional electrical component in addition to the LED is secured to the circuit element; and

a protective capsule of thermoplastic polymer material is molded over the additional electrical component in the first mold cavity.

29. The method of claim 20, wherein:

the one electrical component comprises an integrated circuit having a generally quadrilateral perimeter;

the peripheral edge of the protective capsule has a generally quadrilateral shape.

30. An electrical device, comprising:

a printed circuit board comprising a non-conductive board and a plurality of conductive tracks disposed on the non-conductive board;

a plurality of conductive elements connected to the conductive tracks;

at least one electrical component mounted on the printed circuit board in electrical contact with at least one of the conductive tracks;

a one piece body comprising thermoplastic polymer material encasing the one electrical component and the printed circuit board and contacts at least one of the printed circuit boards and the one electrical component; and

wherein;

at least two of the conductive elements are molded into the one piece body with exposed portions of the conductive elements extending outside of the one piece body to provide an electrical power source, and wherein the one piece body forms a seal around the two conductive elements to prevent entry of moisture.

31. The electrical device of claim 30, wherein:

the electrical component comprises an LED.

32. The electrical device of claim 31, wherein:

the thermoplastic polymer material of the one piece body contacts the LED.

33. The electrical device of claim 30, wherein:

the printed circuit board defines first and second opposite side faces, and the conductive tracks are disposed on the first side face; and

the thermoplastic polymer material contacts a substantial portion of the first and second opposite side faces.

34. The electrical device of claim 33, wherein:

the first and second opposite side faces define a central portion and a peripheral edge portion extending around the central portion, and wherein the thermoplastic polymer material contacts the central portion of at least one of the first and second opposite side faces.

35. The electrical device of claim 30, wherein:

the conductive tracks are disposed on a generally planar first side face of the non-conductive board;

the electrical component includes a peripheral edge surface that extends transversely away from the first side face; and

the thermoplastic polymer material contacts at least a portion of the peripheral edge surface of the electrical component.

36. The electrical device of claim 35, wherein:

the thermoplastic polymer material contacts at least a portion of the conductive tracks.

37. The electrical device of claim 36, wherein:

the printed circuit board defines a second side face opposite the first side face; and

the thermoplastic polymer material contacts the second side face.

38. The electrical device of claim 35, wherein:

the electrical component includes an outer side that faces away from the first side face of the non-conductive board;

the thermoplastic polymer material contacts the outer side of the electrical component.

39. The electrical device of claim 30, wherein:

the conductive elements comprise prongs; and

the thermoplastic polymer material defines a cavity, and the prongs are disposed in the cavity to form a receptacle.

40. A method of fabricating an electrical device, comprising;

providing a printed circuit board;

mounting at least one electrical component on the printed circuit board;

providing a barrier of polymer material that at least partially covers the electrical component;

positioning the printed circuit board and the one electrical component in a mold cavity;

injecting molten thermoplastic polymer material into the mold cavity such that the molten thermoplastic polymer material comes into contact with the barrier.

41. The method of claim 40, wherein:

the barrier comprises thermoplastic polymer material that is molded around the one electrical component after the one electrical component is mounted to the printed circuit board.

42. The method of claim 41, wherein:

the mold cavity comprises a second mold cavity defining a second shape;

the thermoplastic polymer material is molded around the electrical component in a first mold cavity having a first shape that is substantially different than the second shape.

43. The method of fabricating an electrical device of claim 42, wherein:

the barrier includes a generally dome-shaped portion.

44. The method of fabricating an electrical device of claim 43, including:

forming a layer of thermoplastic polymer material on the printed circuit board in the mold cavity; and

forming a groove around the dome-shaped portion of the barrier.

45. The method of fabricating an electrical device of claim 40, wherein:

the barrier covers the one electrical component before the electrical component is positioned in the mold cavity.