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Compositions, methods and devices for high temperature lead-free solder

A composition, solder technology, applied in the direction of electrical components, welding/cutting media/materials, welding equipment, etc., can solve problems such as poor mechanical properties

Inactive Publication Date: 2004-06-23
HONEYWELL INT INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the solidus line of J alloy is 228 ℃, and its mechanical properties are also poor

Method used

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  • Compositions, methods and devices for high temperature lead-free solder
  • Compositions, methods and devices for high temperature lead-free solder

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Embodiment Construction

[0027] Due to differences in thermal expansion coefficients of different materials, solder joints are often subjected to shear loads. Therefore, alloys joining these materials are particularly required to have a low shear modulus and the resulting good thermal mechanical fatigue resistance. For example, low shear modulus and good thermal mechanical fatigue resistance help avoid chip cracking when securing chips, especially when relatively large chips are bonded to solid supports.

[0028] Based on the known elastic moduli of pure metals, Ag and Bi exhibit partial solid-state mutual solubility, and the Ag-Bi system does not contain intermetallic or intermediate phases, the Ag-Bi alloy described in the present invention is stable at room temperature. The shear modulus is in the range of 13-16 GPa (assuming that the shear modulus at room temperature is an additive property - ie the mixture rule described below). The shear modulus of the alloy at room temperature is in the range ...

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Abstract

A lead-free solder comprises an alloy of silver and bismuth in amounts of 2wt% to 18wt% and 98wt% to 82wt%, respectively. Contemplated alloys have a solidus of no lower than 262.5 deg.C and a liquidus of no higher than 400 deg.C. Contemplated alloys may further comprise a chemical element with an oxygen affinity that is higher than the oxygen affinity of the alloy.

Description

technical field [0001] The present invention relates to the field of lead-free solder. Background technique [0002] Most known die attach methods employ high lead solder to attach semiconductor chips in integrated circuits to leadframes to form mechanical connections and to enable thermal and electrical conduction between the die and leadframes. Although most high lead solders are relatively inexpensive and exhibit a variety of favorable physicochemical properties, the use of lead in fixed chips and other solders has been more studied from an environmental and occupational health perspective. Therefore, various measures have been taken to replace lead-containing solder with lead-free chip attach compositions. [0003] For example, one approach is to use a polymer adhesive such as epoxy or cyanate resin to attach the chip to a substrate as described in US Pat. As described in US Pat. No. 5,612,403, at temperatures below 200°C, polymer adhesives generally solidify in a rela...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K35/00B23K35/26C22C5/02C22C12/00C22C13/00C22C13/02H01L21/60
CPCH01L2224/83805H01L2924/01032H01L2224/29113H01L2924/0105H01L2924/01049H01L2924/01025C22C5/02H01L2924/01038H01L2224/83801H01L2924/0132H01L2224/29C22C12/00H01L2924/01013H01L2924/01003H01L2924/01039H01L2224/29298H01L2924/0665H01L2924/0103H01L2224/2919H01L2924/01021H01L2224/04026B23K35/264H01L2924/0104H01L24/83H01L2924/01033H01L24/31H01L2924/01074H01L2924/01078B23K2035/008H01L2924/01051H01L2924/01015H01L2924/01055H01L2924/01082H01L2924/01002H01L2924/01327H01L2924/01019H01L2924/01322H01L2924/01029H01L2924/00013C22C13/02B23K35/00H01L2924/014H01L2224/29101H01L2924/01056H01L2924/01072H01L2924/01047H01L2924/01079H01L2924/14H01L24/29H01L2924/01005H01L2924/01006H01L2924/0106H01L2924/10329H01L2924/0102H01L2924/10253H01L2924/01058H01L2224/8319H01L2924/01012H01L2924/00H01L2924/01014H01L2924/00014H01L2924/01083H01L2924/3512H01L2224/29099H01L2224/29199H01L2224/29299H01L2224/2929C22C13/00
Inventor J·拉勒纳N·迪安M·魏泽
Owner HONEYWELL INT INC
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