Electronics Forum | Mon Nov 12 01:18:29 EST 2007 | sin4d
Hi, ALL I experience some QFP with wetting issue on the heel of the lead. There is no fillet wetting on the heel which causes reject bt the customer, but not all the QFP. Could anyone pls help what is the causes of this problem, it is due to oxidati
Electronics Forum | Tue Sep 14 21:03:42 EDT 2010 | genesan
Hi Sir, The diameter of the aperature is 17mil and thickness 6mil and since we are using Solder Paste Inspection i believe that should have a good paste deposit on this pad.Let say if no good paste it will more create insufficient solder which X-RAY
Electronics Forum | Fri Apr 09 15:00:04 EDT 2010 | davef
So for your SMT1/SMT2/PTH boards, you have poor solderability during SMT2. [Even if you have no SMT2 and only ST1/PTH, our answer is the same.] We assume this occurs on one board part number only. We guess that your bare boards have insufficient gol
Electronics Forum | Tue Sep 14 02:46:17 EDT 2010 | grahamcooper22
Hi Gani, Looking at the pictures in the report it looks as if there is a thin coating of solder on the pcb pad....but it looks like the BGA sphere was barely in contact with the pad. This could be caused by insufficient solder paste on this pad...may
Electronics Forum | Mon Apr 23 17:30:08 EDT 2001 | davef
Step 1: Print paste on the board, skip placement, reflow the board, check solderability. Step 2: Goto Step 1. White Tin Solderability: The most common reason for solderability issues with the white tin surface coating during multiple thermal excur
Electronics Forum | Wed Nov 06 16:31:59 EST 2002 | slthomas
I would also consider paste control (don't take it personally...I always have to get after people about this one), time on the stencil, time between print and reflow, solderability of the component leads, paste volume (that one really got us once....
Electronics Forum | Thu Sep 07 10:32:12 EDT 2006 | slthomas
Is the solder reflowing on the pad but not wicking up the lead, or does there appear to be insufficient solder to wet both, or is it not reflowing at all, or.....? Have you verified your profile? What is the condition of your paste (expiration date,
Electronics Forum | Thu Nov 07 12:35:38 EST 2002 | slthomas
Sounds like you're talking about the "heel" of the lead not being soldered, in other words, no heel fillet, which IS necessary. That problem, for us, was attributed primarily to poor layout (insufficient length of pad extension to provide room for
Electronics Forum | Fri Apr 29 14:16:16 EDT 2011 | ppcbs
Below is the long explanation. This defect is most commonly found with BGA components, but can arrise with all components. I see it happening more now with lead free boards that are being assembled with a no clean flux. Best short term remedy is t
Electronics Forum | Mon Nov 25 09:34:52 EST 2002 | davef
You're correct excessive temperature can cause dewetting, but that usually means realeeee hot. Excessive time at above liquidous will cause dewetting also.
