Semiconductor substrate subassembly with alignment and stress relief features

• US 6,127,727 A
• Filed: 04/06/1998
• Issued: 10/03/2000
• Est. Priority Date: 04/06/1998
• Status: Expired due to Term

• Current Assignee: Delphi Technologies Ip Limited (BorgWarner Incorporated)
• Original Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Eytcheson, Charles Tyler
• Primary Examiner(s): Graybill, David E.
• Application Number:
  US09/055,679
• Time in Patent Office: 911 Days
• Field of Search: 257/692, 257/703, 257/746, 257/748, 257/779
• US Class Current: 257/692
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/37011 comprising apertures or cavities
• CPC Class Codes: H01L 2224/37147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/40091 Arched
• CPC Class Codes: H01L 2224/40225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/73221 Strap and wire connectors
• CPC Class Codes: H01L 2224/83801 Soldering or alloying
• CPC Class Codes: H01L 2224/84801 Soldering or alloying
• CPC Class Codes: H01L 2224/85399 Material
• CPC Class Codes: H01L 23/49562 for devices being provided for in H01L29/00
• CPC Class Codes: H01L 24/37 of an individual strap connector
• CPC Class Codes: H01L 24/40 of an individual strap connector
• CPC Class Codes: H01L 24/41 of a plurality of strap connectors
• 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 24/84 : using a strap connector
• CPC Class Codes: H01L 25/18 : the devices being of types provided for in two or more different subgroups of the same main group of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N
• 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 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/1305 : Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13055 : Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/30105 : Capacitance
• CPC Class Codes: H01L 2924/30107 : Inductance
• CPC Class Codes: H01L 2924/3011 : Impedance

Abstract

A composite conductor for contacting a semiconductor device chip. A durable substrate subassembly for a high power transistor switching modules. The substrate subassembly is durable because wire bonds to the semiconductor device electrodes are replaced with a soldered metal/ceramic composite conductor. The part of the composite conductor contacting the semiconductor device has a coefficient of thermal expansion close to that of the semiconductor device. The substrate in the substrate subassembly has automatic alignment features. The composite conductor also has automatic alignment features, along with stress relief features. Automatic alignment permits concurrent soldering of the chip to the substrate, and the composite conductor to the chip and to a terminal contact.

Claims

1. A composite conductor for use as soldered connector to a semiconductor device made of a semiconductor material having a given thermal expansion coefficient, said composite conductor comprising:

a metal foil having a portion with opposed major surfaces, with one of said opposed surfaces of said portion having adaptations for soldering to one or more contact areas of a semiconductor device made of a semiconductor material having a given thermal expansion coefficient;

a layer of ceramic on the other of said opposed surfaces, said foil and layer of ceramic having a composite thermal expansion coefficient in said portion close to said given thermal expansion coefficient; and

said adaptations in said one surface of said foil including first areas of said metal foil not wettable by molten solder, whereby other areas of said metal foil that can coact with surface tension of molten solder between said metal foil one surface and contact areas on said device chip, and thereby provide automatic alignment configurations on said one surface of said metal foil.

2. The composite conductor as recited in claim 1 wherein:

the first areas of said metal foil surface that are not wettable by molten solder are at least one selected from the class consisting of a coating on said surface and an opening in said surface.

3. The composite conductor as recited in claim 2 wherein:

said opening is a slot through the thickness of said metal foil which exposes a material nonwettable by molten solder material.

4. The composite conductor as recited in claim 1 wherein:

said adaptations include at least one pair of openings in said surface of said metal foil spaced apart a distance similar to a corresponding dimension of a contact areas of said semiconductor device; and

each of said openings are elongated slots surrounding areas on said metal foil surface not wettable by molten solder.

5. The composite conductor as recited in claim 4 wherein:

said metal foil is an strip;

said portion of said metal foil is adjacent one end of said strip;

the opposite end of said strip has second adaptations for soldering to a terminal conductor;

said slots are primarily longitudinally oriented in said strip portion to provide transverse alignment of said strip on said contact areas of said device chip;

said metal foil also contains at least one stress relief configuration between said portion and said opposite end;

said stress relief configuration includes an arch in said strip between said portion and said opposite end;

said one end of said strip has a tip that extends beyond said contact areas of said semiconductor device; and

an upward bend in said tip that can coact with a facing upward bend of said arch and molten solder, to allow surface tension of molten solder to provide longitudinal alignment of said composite conductor on contact surfaces of a device chip when soldering said composite conductor to said contact areas.