Bonding a non-metal body to a metal surface using inductive heating

• US 7,452,800 B2
• Filed: 11/09/2006
• Issued: 11/18/2008
• Est. Priority Date: 11/09/2005
• Status: Expired due to Fees

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Pisano, Albert P., Lin, Liwei, Sosnowchik, Brian D.
• Primary Examiner(s): COLEMAN, WILLIAM D
• Application Number:
  US11/598,244
• Publication Number:
  US 20070105341A1
• Time in Patent Office: 740 Days
• Field of Search: 438/117, 438/122, 438/615, 438/657, 257/E21.088, 257/E21.48, 257/E21.084
• US Class Current: 438/615
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 1/002 Soldering by means of induction heating
• CPC Class Codes: B23K 1/203 Fluxing, i.e. applying flux onto surfaces
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/08 Non-ferrous metals or alloys
• CPC Class Codes: B23K 2103/10 Aluminium or alloys thereof
• CPC Class Codes: B23K 2103/12 Copper or alloys thereof
• CPC Class Codes: B23K 2103/18 Dissimilar materials
• CPC Class Codes: B23K 2103/26 Alloys of Nickel and Cobalt and Chromium
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 2103/54 Glass
• CPC Class Codes: B23K 2103/56 semiconducting
• CPC Class Codes: B81C 3/001 Bonding of two components
• CPC Class Codes: G01L 1/2293 of the semi-conductor type semi-conductor devices controllable by variations of applied mechanical force H01L29/84
• CPC Class Codes: H01L 2224/29111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/2919 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/83222 Induction heating, i.e. eddy currents
• CPC Class Codes: H01L 2224/83801 Soldering or alloying
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 24/83 using a layer connector
• 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 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• 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 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/0133 : Ternary Alloys
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/0665 : Epoxy resin
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/30105 : Capacitance
• CPC Class Codes: H01L 2924/3512 : Cracking
• CPC Class Codes: H05B 3/845 : specially adapted for reflecting surfaces, e.g. bathroom - or rearview mirrors

Abstract

A bonding technique suitable for bonding a non-metal body, such as a silicon MEMS sensor, to a metal surface, such a steel mechanical component is rapid enough to be compatible with typical manufacturing processes, and avoids any detrimental change in material properties of the metal surface arising from the bonding process. The bonding technique has many possible applications, including bonding of MEMS strain sensors to metal mechanical components. The inventive bonding technique uses inductive heating of a heat-activated bonding agent disposed between metal and non-metal objects to quickly and effectively bond the two without changing their material properties. Representative tests of silicon to steel bonding using this technique have demonstrated excellent bond strength without changing the steel'"'"'s material properties. Thus, with this induction bonding approach, silicon MEMS devices can be manufacturably bonded to mechanical steel components for real time monitoring of the conditions/environment of a steel component.

Claims

1. A method of bonding a non-metal body to a metal surface comprising the steps of:

a) contacting a silicon device with a steel mechanical component with a heat activated bonding agent therebetween; and

b) heating the heat activated bonding agent by heating the component with an inductive heater to bond the silicon device to the steel mechanical component.

2. The method of claim 1, wherein the heat activated bonding agent is selected from the group consisting of solder, brazing material, and heat-setting adhesive.

3. The method of claim 1, wherein the silicon device is a silicon chip.

4. The method of claim 1, wherein the silicon device comprises a MEMS device.

5. The method of claim 1, wherein the steel comprise a bearing race.

6. The method of claim 2, wherein the heat activated bonding agent comprises solder.

7. The method of claim 4, wherein the MEMS device is a MEMS sensor.

8. The method of claim 5, wherein the silicon device comprises a MEMS strain sensor.

9. The method of claim 7, wherein the MEMS sensor is an accelerometer.

10. The method of claim 7, wherein the MEMS sensor is a gas sensor.

11. The method of claim 7, wherein the MEMS sensor is a pressure sensor.

12. The method of claim 6, wherein the solder is applied to the steel mechanical component prior to contacting the silicon device and the metal surface.

13. The method of claim 6, wherein the solder is applied to the silicon device prior to contacting the silicon device and the metal surface.

14. The method of claim 6, further comprising an adhesion layer between the non-metal body and metal surface.

15. The method of claim 6, wherein the solder comprises Pb.

16. The method of claim 6, wherein the solder is Pb-free.

17. The method of claim 6, wherein the solder comprises flux.

18. The method of claim 6, wherein the inductive heating has a duration of less than 10 seconds.

19. The method of claim 6, wherein the inductive heating has a duration of less than 5 seconds.

20. The method of claim 6, wherein the material properties of the steel are substantially unaffected by the soldering operation.

21. The method of claim 6, wherein, prior to application of the solder, the steel surface is prepared for bonding by removing native oxide.

22. The method of claim 13, wherein a pressure is applied during heating to promote contact of the silicon device, bonding agent and metal surface.

23. The method of claim 14, wherein the adhesion layer comprises a metal.

24. The method of claim 16, wherein the solder is a tin-silver-copper solder.

25. The method of claim 21, wherein the surface preparation comprises cleaning and roughening.

26. The method of claim 23, wherein the adhesion layer metal is selected from the group consisting of Ni, Au, Ag and Cu.

27. The method of claim 26, wherein the adhesion layer metal is Ni.

28. The method of claim 27, wherein a thin layer of a solder is applied to the adhesion layer to prevent oxidation prior to bonding.

29. A method of bonding a non-metal body to a metal surface comprising the steps of:

a) contacting the non-metal body with a non-ferromagnetic metal surface selected from the group consisting of Al and Cu with a heat activated bonding agent therebetween; and

b) heating the heat activated bonding agent by heating the metal surface with an inductive heater to bond the non-metal body to the metal surface.

30. The method of claim 29, wherein the metal surface is Al, the heat activated bonding agent comprises solder and the non-metal body comprises silicon.

31. The method of claim 30, wherein the solder is a tin-zinc solder.

32. A method of bonding a non-metal body to a metal surface comprising the steps of:

a) forming a seed layer on the surface of the non-metal body;

b) forming an adhesion layer on the seed layer;

c) contacting the non-metal body with the metal surface with the seed layer, adhesion layer and a heat activated bonding agent therebetween; and

d) heating the heat activated bonding agent by heating the metal surface with an inductive heater to bond the non-metal body to the metal surface.

33. The method of claim 32, wherein the seed layer is selected from chromium-copper, chromium-nickel, chromium-gold, titanium-copper, titanium-nickel, titanium-gold, chromium and titanium.

34. A method of bonding a silicon body to a steel surface comprising the steps of:

a) forming an adhesion layer of nickel on a surface of the silicon body;

b) applying solder to the steel surface;

c) placing the silicon body on the steel surface with the layer of nickel adjacent to the solder; and

d) heating the solder by heating the steel surface with an inductive heater for less than 5 seconds to solder the nickel layer to the steel surface.