Electronics Forum | Fri Sep 22 08:37:07 EDT 2000 | Erick Russell
For any rework machine a good optics system is important. A look-up look down is used for BGA components. 30X magnification is required for flip chip, MicroBGA and fine pitch QFP placement. Digital cameras are not required, CCD have a good enoug
Electronics Forum | Thu Aug 24 13:31:55 EDT 2000 | Dave F
At room temperature, how long does it take for the phases of a common tin (Sn) / lead (Pb) solder, say 60/40, to reach equilibrium? While the materials are diffusing toward equilibrium do the material properties of the solder change significantly?
Electronics Forum | Thu Aug 24 16:54:33 EDT 2000 | Dr. Ning-Cheng Lee
52In/48Sn solder has a melting point 118C, and can be reflow processed at temperature down to around 165-170C. The material is very soft, very low in shear strength. It is relatively ductile, can be stretched to about 2-3X of Sn63 in elongation. Amon
Electronics Forum | Thu Aug 24 13:18:24 EDT 2000 | Dave F
What are the primary indium (In) / tin (Sn) intermetallic compounds (IMC)? What are the drivers to the formation of In/Sn IMC? Copper / tin IMC are very bittle and, while necessary for proper solder connection formtion, are ment to be minimized. W
Electronics Forum | Thu Aug 24 16:44:27 EDT 2000 | Dr. Ning-Cheng Lee
There is no IMC composition can be identified in phase diagram of In/Sn. There are some compositions such as In3Sn or InSn4 cited in earlier literature. Those composition should be regarded as approximate representation of solid solution of In/Sn. I
Electronics Forum | Wed Aug 23 19:01:54 EDT 2000 | kbmacg
For high temperature electronics, operating in 225�C ambient environments, most solders can not be used. The high-lead solders all have difficulties of one sort or another. Is their anything new regarding useful high melting point solders? Especially
Electronics Forum | Wed Aug 23 16:57:10 EDT 2000 | Dr. Ning-Cheng Lee
Regarding solder paste printing, many books available on the market all have some sections addressing this topic. Unfortunately, as of today, solder paste printing has not been the main theme of any book yet. I consider the better sources of informat
Electronics Forum | Fri Aug 30 04:53:08 EDT 2002 | jason
Hi Dr Lee, Recently, I was assigned to use Ag imm. PCB using 63/37 solder paste without Ag. The results were not fantastic. Surface finish was rough and lots of wetting issue. The oven profile soaking time was set at 70 secs above 183�C and Max tem
Electronics Forum | Wed Aug 23 16:40:30 EDT 2000 | Dr. Ning-Cheng Lee
During the second reflow, the solder remelts and resolidifies. In general, the reflow temperature is not high enough to erase the microstructure developed during the first reflow. As a result, the net effect of a second reflow typically is grain coar
Electronics Forum | Thu Aug 24 13:51:24 EDT 2000 | Dr. Ning-Cheng Lee
Low temperature aggravates the mismatch in thermal expansion between solder and parts and between components and boards, therefore can induce earlier failure. The low temperature screening test should not be as effective when used on soft solders su
