Influence of lead frame thickness on the flexure resistance and peel strength of thermocompression bonds
The flexure resistance and peel strength of 0.18 mm and 0.25 mm thick lead frames, which were thermocompression bonded to metallized ceramic substrates, were determined. Comparison was made on the basis of existing bonding thermodes with parameters varied to yield a range of bond zone deformations extending from 20 to 65 percent. Bond strength was evaluated through a 90/sup 0/ peel test, while flexure resistance was determined through a cycle of 30/sup 0/ flex and return with a 200 g deadweight attached to the lead. Results of this study indicate that: (1) the flexure resistance of thermocompression bonded 0.18 millimeter leads was significantly greater (at least 50 percent increase in cycles to failure) than that for 0.25 millimeter leads; (2) the flexure resistance for both lead frame thicknesses decreased with increasing bond zone deformation; (3) tool configuration, especially rail edge radius, is a major contributing factor in the flexure resistance of lead frame bonds; and (4) consistently high peel strength was more easily maintained with 0.18 mm leads. (The 0.25 millimeter leads exhibited a greater sensitivity to bonding parameters which resulted in both very high and very low peel strength values.) The results were further compared to those from a previous investigation of 0.13 and 0.18 mm lead frames with regard to bondability and flexure resistance. The combined data from the two separatestudies reveal that the 0.18 mm leads yielded an increase in flexure resistance of 80 and 53 percent over the 0.13 and 0.25 mm thick leads respectively. (auth)
- Research Organization:
- Sandia Labs., Albuquerque, N.Mex. (USA)
- DOE Contract Number:
- AT(29-1)-789
- OSTI ID:
- 7296146
- Report Number(s):
- SAND-75-0304
- Country of Publication:
- United States
- Language:
- English
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