Electronics Forum | Tue Jul 28 16:37:24 EDT 1998 | Terry Burnette
| I think that in general it's best to deposit paste in order to increase the part standoff. This helps improve the fatigue-life of the joints by providing more strain relief. But I know from experience that it's tough to deposit paste during the r
Electronics Forum | Thu Jul 23 13:11:13 EDT 1998 | Gestapo Allen
I think that in general it's best to deposit paste in order to increase the part standoff. This helps improve the fatigue-life of the joints by providing more strain relief. But I know from experience that it's tough to deposit paste during the rew
Electronics Forum | Sun Apr 03 10:07:40 EDT 2005 | davef
In 2001, IVF evaluated the reliability of IBM CBGA and CCGA, i.e. packages with "hard" balls and columns, in space applications for the European Space Agency. One clear result was that amount of solder paste printed on the solder lands is very critic
Electronics Forum | Wed Feb 03 15:18:25 EST 1999 | Michael Allen
I'd like to find some technical papers on the reliability of reworked BGAs. If you know of any, please let me know. I have a concern about this because our current rework process does not apply solder paste to the pads prior to placing the part; th
Electronics Forum | Thu Dec 07 19:54:55 EST 2006 | davef
We agree with "guest" above. This a "chip bonder" type material used to improve the reliability of array type devices. "A relative comparison of the N50 values is given below: No underfill = 1.0X (baseline) Corner bond = 1.3X Non reworkable underfi
Electronics Forum | Thu Aug 24 17:08:58 EDT 2000 | Dr. Ning-Cheng Lee
Depending on the stress condition experienced by the solder joints. For joints under a greater stress, the time to reach equilibrium can be shorter. Of course, the change is also more significant in phase structure. For low stress conditions, it may
Electronics Forum | Tue Jan 13 20:52:21 EST 2004 | davef
Bismuth Solder alloys * Fatigue life is reduced when soldered to hot air solder leveled (HASL) boards. * Lead from Hot Air Leveling (HAL) coatings can diffuse through the grain boundaries of alloy. * Lead is bismuth alloys can form a eutectic composi
Electronics Forum | Sat Sep 25 08:59:59 EDT 2004 | davef
IPC-HDBK-830, Guidelines for Design, Selection and Application of Conformal Coatings says: A conformal coating may have several functions depending on the type of application. The most common are: * Inhibit current leakage and short circuit due to h
Electronics Forum | Thu Mar 28 13:19:14 EDT 2019 | davef
There is no industry standard for BTC stand-off height. "IPC-7093A Design and Assembly Process Implementation for Bottom Termination SMT (BTC) Components" just finished "Final Draft for Industry Review" in December 2018. It mentions stand-off height
Electronics Forum | Fri Apr 20 07:54:25 EDT 2007 | Bob R.
I'm in the high reliability (exempt) sector and have thermal cycled hundreds of boards in the past few years. As far as which is more reliable, SnPb or SAC305, my data is similar to what the technical literature is saying, "It Depends". In low stra
