Composite substrates for preparation of printed circuits

• US 5,565,267 A
• Filed: 06/07/1995
• Issued: 10/15/1996
• Est. Priority Date: 02/09/1990
• Status: Expired due to Term

• Current Assignee: Ormet Circuits, Inc. (Merck & Co., Inc.)
• Original Assignee: Toranaga Technologies, Inc.
• Inventors: Todd, Michael G., Capote, Miguel A.
• Primary Examiner(s): McCamish, Marion E.
• Assistant Examiner(s): Copenheaver, Blaine R.
• Application Number:
  US08/478,453
• Time in Patent Office: 496 Days
• Field of Search: 428/344, 428/901, 428/458, 252/512, 252/513, 252/514, 252/518
• US Class Current: 428/344
• CPC Class Codes: B23K 35/0222 for use in soldering, brazing B23K35/0205 takes precedence
• CPC Class Codes: B23K 35/36 Selection of non-metallic compositions, e.g. coatings, fluxes B23K35/34 takes precedence; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest selection of soldering or welding materials proper B23K35/24
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01L 2224/293 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 23/49883 the conductive materials containing organic materials or pastes, e.g. for thick films for printed circuits H05K1/092
• CPC Class Codes: H01L 23/5384 Conductive vias through the substrate with or without pins, e.g. buried coaxial conductors H01L23/5383, H01L23/5385 take precedence; pins attached to insulating substrates H01L23/49811
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01087 Francium [Fr]
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 1/181 associated with surface mounted components
• CPC Class Codes: H05K 2201/0272 Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
• CPC Class Codes: H05K 2201/10378 Interposers
• CPC Class Codes: H05K 2203/0425 Solder powder or solder coated metal powder
• CPC Class Codes: H05K 2203/1105 Heating or thermal processing not related to soldering, firing, curing or laminating, e.g. for shaping the substrate or during finish plating
• CPC Class Codes: H05K 3/321 by conductive adhesives
• CPC Class Codes: H05K 3/3489 Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates
• CPC Class Codes: H05K 3/4623 the circuit boards having internal via connections between two or more circuit layers before lamination, e.g. double-sided circuit boards H05K3/462 takes precedence
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 428/2804 : Next to metal
• CPC Class Codes: Y10T 428/31511 : Of epoxy ether
• CPC Class Codes: Y10T 428/31529 : Next to metal
• CPC Class Codes: Y10T 428/31681 : Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Abstract

Substrates for printed circuit boards and the like, in the form of a substrate base layer and at least one adherent layer fixedly attached thereto. The adherent layer preferably comprises a thermoplastic material having a glass transition temperature in the range of about 180° and about 245° C., or a thermosetting material capable of B-stage curing. The preparation of the novel substrates and printed circuits using the substrates and conductive traces formed with electrically-conductive ink compositions is also described.

Claims

1. A printed circuit board comprising:

(a) a substrate comprising;

a substrate base layer; and

at least one adherent layer fixedly attached to the substrate base layer, said at least one adherent layer comprising a thermoplastic material having a heat deflection temperature in the range of about 180°

C. and about 245°

C., said at least one adherent layer serving to provide a surface; and

(b) conductive traces, comprising an electrically conductive adhesive composition, that form an electrical interconnect pattern bonded onto said surface of said at least one adherent layer, wherein the electrically conductive adhesive composition comprises (1) a high melting point metal, (2) a low melting point metal, (3) a cross-linking agent mixture comprising a protected curing agent and (4) at least one of (i) a resin or (ii) a reactive monomer or polymer which can be cross-linked by the curing agent.

2. The printed circuit board according to claim 1 wherein said substrate base layer has a decomposition temperature that is higher than the curing temperature of said electrically conductive adhesive composition.

3. The printed circuit board according to claim 1 wherein said thermoplastic material is selected from the group consisting of polyetherimides, polyethersulfones, polyarylsulfones, polyimides, polyimidesiloxanes, and aromatic polyesters.

4. The printed circuit board according to claim 1 wherein said substrate base layer comprises a metal and said at least one adherent layer electrically insulates said conductive traces from said substrate base layer.

5. The printed circuit board according to claim 4 wherein the metal has a melting point of at least 250°

C.

6. The printed circuit board according to claim 1 wherein said electrically conductive adhesive composition comprises the resin and the reactive monomer or polymer which can be cross-linked by said curing agent.

7. The printed circuit board according to claim 1 wherein the high melting point metal is selected from the group consisting of copper, silver, aluminum, gold, platinum, palladium, beryllium, rhodium, nickel, cobalt, iron, molybdenum, and alloys thereof.

8. The printed circuit board according to claim 7 wherein the low melting point metal is selected from the group consisting of tin, bismuth, lead, cadmium, zinc, gallium, indium, tellurium, mercury, thallium, antimony, selenium, and alloys thereof.

9. The printed circuit board according to claim 1 wherein the low melting point metal is selected from the group consisting of tin, bismuth, lead, cadmium, zinc, gallium, indium, tellurium, mercury, thallium, antimony, selenium, and alloys thereof.

10. The printed circuit board according to claim 1 wherein the electrically conductive adhesive composition comprises:

(1) 1-65% of a metal powder selected from the group consisting of copper, silver, aluminum, gold, platinum, palladium, beryllium, rhodium, nickel, cobalt, iron, molybdenum and alloys thereof;

(2) 6-65% of a solder wherein said solder is selected from the group consisting of Sn, Bi, Pb, Cd, Zn, Ga, In, Te, Hg, Tl, Sb, Se, and alloys thereof;

(3) 0.01-61% of a chemically protected cross-linking agent with fluxing properties; and

(4) (i) 1-45% of the resin or (ii) 1-50% of the reactive monomer or polymer, with all percentages based on volume.

11. The printed circuit board according to claim 10 wherein said solder is a metal mixture that includes a metal additive that raises the melting temperature of the solder, said metal additive is selected from the group consisting of nickel and silver wherein said metal additive comprises 1 to 10 weight percent of the total metals content of the composition.

12. The printed circuit board according to claim 10 wherein said solder powder is an alloy comprising Sn63Pb37.

13. The printed circuit board according to claim 10 wherein said chemically protected cross-linking agent with fluxing properties is an acid or a strong base which is protected so as to become reactive only at or near a time at which the solder powder is melted.

14. The printed circuit board according to claim 13 wherein said acid or strong base is selected from the group consisting of anhydrides, carboxylic acids, amides, imides, amines, alcohols, phenols, aldehydes, ketones, nitro compounds, nitriles, carbamates, isocyanates, amino acids, peptides, thiols, sulfonamides, semicarbazones, oximes, hydrazones, cyanohydrins, ureas, phosphoric acids, phosphoric esters, thiophosphoric acids, thiophosphoric esters, phosphonic acids, phosphonic esters, phosphites, phosphonamides, sulfonic acids and sulfonic esters.

15. The printed circuit board according to claim 13 wherein said acid or strong base is an anhydride.

16. The primed circuit board according to claim 10 wherein the metal powder comprises 13-65% by volume of said composition.

17. The printed circuit board according to claim 16 wherein the solder comprises 6-29% by volume of said composition, the cross-linking agent comprises 7-60% by volume of said composition, and the resin comprises 1-15% or the reactive monomer or polymer comprises 1-32% by volume of said composition.