Electronics Forum | Tue Mar 20 20:14:40 EST 2001 | davef
Electroplating [electrolytic] and dipping [HASL] are the two methods for applying solder coatings to features on boards. Disadvantages of electroplating lead / tin are: * "Weak knees" created at the edge of plated through holes. [I used to get weak k
Electronics Forum | Thu Apr 05 10:50:08 EDT 2001 | CAL
Per our staff here at ACI......... Higher Temperatures maybe necessary to achieve good solder process results. The alloy formed when HASL coating protects the copper is the same as that when OSP provide protection. Temperatures may be increased to im
Electronics Forum | Tue Aug 28 14:21:39 EDT 2001 | Scott B
You have to be careful here. The figure is expressed as placement accuracy, not process quality therefore 3 sigma does not relate to 2700 PPM defects but 2700 parts per million placed outwith 15microns (0.0006" / 0.6thou). Extrapolating the distribu
Electronics Forum | Wed May 30 21:16:05 EDT 2001 | davef
MPM AP-27 preferred over MPM AP-20 The issue is release of paste from the stencil. A vertical lift printer kinda snaps the stencil away from the board to complete the print cycle. The inertia and the rheometric properties of the paste make it rele
Electronics Forum | Thu Jun 14 21:06:49 EDT 2001 | davef
We rate each board for producibility. [Our rating chart may be based on some things that Bob Willis did. Check his site [http://www.bobwillis.co.uk/ ] for all kinds of neat stuff. Maybe even bring him in to help you sort through things.] There
Electronics Forum | Mon Jun 18 22:04:01 EDT 2001 | davef
YA DON NEDA YELL!!! AHYAINT DAFF YANO!!! Printing adhesive near fine pitch devices can risky. Be careful. Look here to get started: http://www.alphametals.com/products/techarticles/soldrpstncl/guidelines.html [I know this link is expired, but may
Electronics Forum | Mon Jul 09 14:03:39 EDT 2001 | ohboy
Make sure you're getting a good roll from your squeegies. Poly will "scoop", leaving less, nickel will add a little extra. A slightly shorter blade height out of the holders will help promote a good roll- this helps push the paste into the thru h
Electronics Forum | Mon Dec 27 12:24:47 EST 1999 | RICK_EEI
Hi everyone. We use a small ultrasonic aqueous cleaner. After each PCB we hand solder, (water soluble) we place it in the cleaner immediately. Lately we have had some problems with the solder joints appearing to be corroding away. We tried lowering t
Electronics Forum | Tue Dec 14 11:08:19 EST 1999 | John Thorup
I think you're on the right track Paul. You didn't mention what type of solder mask was used but I'll presume that it was LPI (liquid photo imagable). If development of the image is incomplete some mask can remain where it is unwanted. Sometimes im
Electronics Forum | Fri Nov 12 10:36:33 EST 1999 | Dave F
Wolfgang: Sure, stacking chip components is common practice in prototyping, as you say, but it's not good practice for production work. Documentation: * ANSI-IPC-275 does not allow stacking * MIL-STD-2000A does not allow stacking * J-STD-001B is u
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