Electronics Forum | Thu Jun 06 07:28:30 EDT 2002 | cyber_wolf
It has been my experience that the only thing(s) that will ever cause this is: 1. Operators with paste on their hands. 2. Paste on the screen printer tooling. 3. Paste on the bottom of the stencil. Even very very small amounts of paste on the gold fi
Electronics Forum | Fri Mar 07 21:02:21 EST 2003 | neil
When printing below .5mm pitch, the recommended stencil thickness is 5Thou, laser cut. Do not use any reduction and ensure wherever possible the pad to space ration is 1:1, the length of the pad is not as important as the gap between adjacent pads. T
Electronics Forum | Wed May 21 12:55:35 EDT 2003 | Zhenya
Several things for your reference: 1. Starting with data collection: - Have you done a measle chart to illustrate the pattern of the defect? - Have you checked the corelation between shift/time and defects rate? - How about a pareto chart? - Do
Electronics Forum | Mon Oct 06 12:37:18 EDT 2003 | ramanandkini
It was a nice discussion. What I did here was a thermal shock test 1 hour@ +90 deg.c and immediately 1 hour @ -40 deg.c. The second test I did was a high humudity test for a week. After each test, I carried out a peel test with scotch tape. Those bo
Electronics Forum | Wed Mar 31 20:34:03 EST 2004 | davef
We have not used this specific package. We agree on your toe fillet idea. Toe fillets add no strength to solder connections. This part is a MicroLeadFrame�, which is similar to QFN, BCC, LGA, and whatnot. Consider: * Searching the fine SMTnet Arch
Electronics Forum | Tue Sep 21 10:53:53 EDT 2004 | davef
We know nothing about Envivar UV 1244 and you weren't real clear about the details of the problem or the materials [eg, ws flux, solder mask, etc], but we'd speculate your adhesion problem goes back to the cleanliness of your board. First by 'alcoho
Electronics Forum | Tue Sep 21 11:34:10 EDT 2004 | davef
Several things to check are: * Ask Multicore if their flux res and your conformal coat are compatible. Conformal coats and NC flux res are notorious for having compatibily issues. * Conformal coat a bare board to determine if there is there is enoug
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 | Fri Oct 08 09:43:27 EDT 2004 | davef
First, don't get too excited about the thermal capabilities of conductive epoxy. An epoxy like DuPont CB-100 increases the amount of heat conducted through the barrel, but many over estimate what it can do. Calculations show for a 0.020" drilled
Electronics Forum | Fri Feb 24 13:39:35 EST 2006 | Chunks
I agree with Jerry. A 7 mil stencil should work just fine for 25 mil pitch parts and 0.050 pitch BGA's. I too go 6 mil, but whith proper screen printing, you can 7 mil. You can always do 5 ot 10% reductions if needed. Use the homeplate design on
