Electrical interconnection substrate with both wire bond and solder contacts

• US 5,311,404 A
• Filed: 06/30/1992
• Issued: 05/10/1994
• Est. Priority Date: 06/30/1992
• Status: Expired due to Fees

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Trask, Philip A., Pillai, Vincent A., Gierhart, Thomas J.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Whang, Young
• Application Number:
  US07/906,637
• Time in Patent Office: 679 Days
• Field of Search: 361/380, 361/388, 361/396, 361/400-403, 361/411, 361/417, 361/418, 361/707, 361/744, 361/743, 361/760, 361/761, 361/765, 361/762, 361/767, 361/807, 361/808, 361/810, 174/255, 174/256, 174/260, 174/261, 174/263, 257/686, 257/779
• US Class Current: 361/762
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 1/018 Unsoldering; Removal of melted solder or other residues
• CPC Class Codes: B23K 1/08 Soldering by means of dipping in molten solder
• CPC Class Codes: B23K 1/085 Wave soldering
• CPC Class Codes: H01L 21/4846 Leads on or in insulating or insulated substrates, e.g. metallisation H01L21/4821 takes precedence; metallisation of ceramics in general C04B41/51; printed circuits H05K3/00
• CPC Class Codes: H01L 21/4864 Cleaning, e.g. removing of solder
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05073 Single internal layer
• CPC Class Codes: H01L 2224/05556 in side view
• CPC Class Codes: H01L 2224/056 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 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/4847 the connecting portion on the bonding area of the semiconductor or solid-state body being a wedge bond
• CPC Class Codes: H01L 2224/48624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48644 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48647 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/81801 : Soldering or alloying
• CPC Class Codes: H01L 23/538 : the interconnection structure between a plurality of semiconductor chips being formed on, or in, insulating substrates H05K takes precedence; manufacture or treatment H01L21/4846 ; mountings per se H01L23/12; materials H01L23/49866
• CPC Class Codes: H01L 24/03 : Manufacturing methods
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/80 : Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 25/0655 : the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01022 : Titanium [Ti]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01032 : Germanium [Ge]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H05K 2201/0154 : Polyimide
• CPC Class Codes: H05K 2201/0305 : Solder used for other purposes than connections between PCB or components, e.g. for filling vias or for programmable patterns
• CPC Class Codes: H05K 2201/0391 : Using different types of conductors
• CPC Class Codes: H05K 2203/0361 : Stripping a part of an upper metal layer to expose a lower metal layer, e.g. by etching or using a laser
• CPC Class Codes: H05K 2203/044 : Solder dip coating, i.e. coating printed conductors, e.g. pads by dipping in molten solder or by wave soldering
• CPC Class Codes: H05K 2203/049 : Wire bonding
• CPC Class Codes: H05K 2203/0585 : Second resist used as mask for selective stripping of first resist
• CPC Class Codes: H05K 3/0041 : by plasma etching
• CPC Class Codes: H05K 3/067 : Etchants
• CPC Class Codes: H05K 3/243 : characterised by selective plating, e.g. for finish plating of pads selective plating for making the circuit pattern H05K3/108, H05K3/182
• CPC Class Codes: H05K 3/28 : Applying non-metallic protective coatings H05K3/0091 takes precedence; methods for intermediate insulating layers for build-up multilayer circuits H05K3/4673
• CPC Class Codes: H05K 3/328 : by welding
• CPC Class Codes: H05K 3/3452 : Solder masks
• CPC Class Codes: H05K 3/3468 : Applying molten solder
• CPC Class Codes: Y10T 29/49144 : by metal fusion

Abstract

An electrical interconnection substrate (20) is prepared to receive both wire bonded and soldered connections (60,64,66) by forming a dielectric solder mask (30) over the substrate (20), with openings (36) in the mask (30) to expose the contact pads (22) for which soldered connections are desired. The substrate (20) is exposed to a molten solder alloy (44) in a wave soldering process that dissolves the wire bonding material (28) (preferably gold) from the exposed pads (22) and deposits solder bonding pads (52) in its place. Excess solder is then removed from the substrate, and openings (54) are formed through the solder mask (30) to expose the wire bond contact pads (22'"'"'). The selective dissolving of gold bonding layers (28) and their replacement by solder pads (52) prevents the establishment of brittle gold-solder intermetallics, and the deposited solder (52) requires no further heat treatment for correct alloy formation.

Claims

1. An electrical interconnection substrate capable of receiving electrical circuit elements by both wire bonding and soldering, comprising:

a substrate having a plurality of electrical contact pads and an electrical interconnection network establishing connections with said contact pads,

a solder mask over said substrate capable of withstanding a molten solder alloy,

openings in said solder mask exposing said contact pads,

some of said contact pads having respective layers of conductive wire bonding material exposed through their respective solder mask openings, and

others of said contact pads having respective layers of solder alloy exposed through their respective solder mask openings.

2. The electrical interconnection substrate of claim 1, wherein said solder mask comprises polyimide.

3. The electrical interconnection substrate of claim 1, wherein said layers of conductive wire bonding material are provided on their respective contact pads thick enough to be wire bondable, but thin enough to dissolve when exposed to a molten solder alloy.

4. The electrical interconnection substrate of claim 3, wherein said contact pads with said layers of conductive wire bonding material comprise respective layers of a conductive, substantially non-ductile material surmounted by respective layers of gold about 1-5 microns thick.

5. The electrical interconnection substrate of claim 1, further comprising at least one integrated circuit (IC) chip wire bonded to at least some of said contact pads that have an exposed layer of conductive wire bonding material, and at least one IC chip solder connected to at least some of said other contact pads that have an exposed layer of solder alloy.