Semiconductor device manufacturing: process – Including control responsive to sensed condition
Patent
1997-01-09
1999-09-21
Niebling, John F.
Semiconductor device manufacturing: process
Including control responsive to sensed condition
438 15, 438455, 438456, 438457, 438458, 438459, 438612, 324765, 324766, 324767, 324768, 324769, 713300, 713501, H01L 2100
Patent
active
059565632
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for reducing a transient thermal mismatch between a first component and a second component which are mechanically in contact.
It is known from the prior art that mismatches in coefficients of thermal expansion of two components which are in contact with each other causes mechanical strain which can lead to the failure of the connection between the components. In particular surface mounted devices often show solder joint cracking due to mismatches in coefficients of thermal expansion between the card, the lead, the chip and the packaging mould compound. It is proposed in U.S. Pat. No. 5,367,124 to minimize this problem by reducing the cross sectional area of that portion of the lead subject to greatest movement due to thermal cycling. Thereby also the problem of solder joint cracking is helped.
Another approach is described in U.S. Pat. No. 4,764,848 where an electronic module or substrate is mounted to the surface of a printed circuit board by means of a plurality of bend or deformed pins. The bend pin design provides 3-dimensional strain relief of former stresses and/or mechanical stresses due to flexure and torque.
From IBM Technical Disclosure Bulletin, Vol. 37, No. 4B, April 1994, pp. 137-140 a solder ball connect design with improved reliability is known. Because the coefficients of thermal expansion mismatch between the module and card, the solder ball joints experience strain during power cycling of the device. Some themal strain is also present due to bending of the module-card assembly again due to the thermal expansion mismatch. To address this problem the proposed design uses corner pins instead of balls, which are soldered into through-holes in the card. This results an improved reliability of all of the solder connections in the array.
Other approaches to address this problem are known from IBM Technical Disclosure Bulletin, Vol. 36, No. 7, July 1993, pp. 199-200, "Method of Reducting Thermal Stress on Ceramic Substrate of Thermal Conduction Module", IBM Technical Disclosure Bulletin, No. 5, October 1991, pp. 466-467, "Relief of Residual Stress in Solder Fillet", IBM Reserch Disclosure, No. 322, February 1991, "Flex Interconnect between Transistor/Diode Leads and Ceramic Substrate" and IBM Reserch Disclosure, No. 309, January 1990, "Solder Joint Life Improvement Using Adhesive under Component".
Furthermore, the thermal mismatch problem is also addressed in the following IBM Technical Disclosure Bulletins: I/C Packaging Applications"; TDB, September 1989, pp. 436-437, "Decal With Power/Ground Plane Partitioned by Thermal Coefficient of Expansion"; TDB, September 1989, pp. 7-8, "Stress Reliever for Single In-Line Package (Sip) Solder Joints"; TDB, September 1989, pp. 365-366, "Strain Relief and Card Retention for Duplex Fiber-Optic Packaging"; TDB, January 1989, pp. 135-138, "Thin Film Module"; TDB, April 1987, pp. 4736-4737, "Area Array Substrate-To-Carrier Interconnection Using Corner Standoff"; TDB, September 1982, p. 1843, "I/O Lead Isolation to Prevent Solder Joint Fatigue"; TDB, August 1979, p. 950, "Circuit Package With Improved Fatigue Life"; TDB, February 1972, pp. 2595-2596, "Balance Straining Package"; TDB, April 1969, p. 1559, "Composite Structures for Modifying Thermal Coefficient of Expansion".
U.S. Pat. No. 4,764,848 contemplates the problem when array substrates are mounted directly to printed circuit boards. The substrates themselves tend to be relatively rigid and inflexible, but the thermal coefficients of expansion differ between the material of which a printed circuit board is comprised and a second material of which a substrate to be mounted is comprised, causing a strain therebetween. As an example when subjected to changes of temperature, an epoxy printed circuit board tends to expand at as much as five times the rate of ceramic that is used to form a substrate. This prior art teaching proposes to solve this problem by a surface mounted array strain relief device comprising an electrical conductor having at least two bends for providing s
REFERENCES:
patent: 5278457 (1994-01-01), Fujita et al.
patent: 5407863 (1995-04-01), Katsura et al.
patent: 5490059 (1996-02-01), Mahalingaiah et al.
patent: 5498971 (1996-03-01), Turnbull et al.
patent: 5502838 (1996-03-01), Kikinis
patent: 5664201 (1997-09-01), Ikedea
patent: 5713030 (1998-01-01), Evoy
IBM Technical Bulletin, vol. 31, No. 8, Jan. 1989, New York USA, pp. 349-350, `Method of Controlling Transient Temperature Differential of Integrated Circuits and Substrates`.
Frech Roland
Garben Bernd
Harrer Hubert
Klink Erich
Schmunkamp Dietmar
Ehrlich Marc A.
International Business Machines - Corporation
Niebling John F.
Zarneke David A.
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