Electronics Forum | Wed Nov 06 10:03:59 EST 2013 | rgduval
Hi, Peter, I'm not an authority on surface finish thickness, and it's effect on reflowing, so, I can't advise on that front. If the boards are a week old, and ENIG, I would not suspect surface contamination. It's always a consideration, of course,
Electronics Forum | Wed May 14 12:42:16 EDT 2008 | rgduval
Dave, Realized I didn't respond to one of your questions. We pasted and reflowed one board, with no components. This board exhibited extreme dewetting on all pads. The board was LF-HASL, and the paste was Qualitek (which we've used for approximat
Electronics Forum | Tue Jul 30 10:04:51 EDT 2002 | dason_c
Dave, I am very interesting to know about the dewetting or pull back, we are currently use the uP78 paste. Will nitrogen, profile setting help to reduce the dewetting. Thank.
Electronics Forum | Mon May 12 17:59:55 EDT 2008 | rgduval
We're currently experiencing a spate of solder not wetting to pads of PCBs, and it's becoming more aggravating on a daily basis. At this point, we're running out of ideas. I've searched the Fine Archives for information, and, so far, haven't found
Electronics Forum | Tue Jul 30 08:37:39 EDT 2002 | davef
When you talk about 'poor wetting', 'dewett', 'no wets', etc.; are you seeing solder pulling back or away from the pad? Please describe the condition. Dewetting. The condition in the solder joint in which the liquid solder has not adhered intimate
Electronics Forum | Tue Jul 30 17:47:50 EDT 2002 | davef
Dewetting: Solder does not adhere to lead or land, caused by: * Poor solderability of lands. * Poor solderability of leads. * Solder paste integrity. * Lead plating integrity. Need more information, please: * What is dewetting [ie, component, pad, e
Electronics Forum | Tue Jul 30 17:51:18 EDT 2002 | davef
Comments are: * Peak at 245�C for 40 sec seems like a very long time. I�d expect the time at 245�C to be 10 to 15 sec. This long time at peak could dewett the pads. * Really, their 2D vision on the printer can verify solder presence? * A thin coat
Electronics Forum | Tue May 13 20:48:10 EDT 2008 | davef
Rob On your thermal recipe: Above liquidous for nearly 2 minutes seems to be a scoush long. Not sure you're doing anything positive with things like that. On the article: * SMT Magazine, October, 2002, p24 'Q & A: BGA Dewetting' * "Q: Our manufactu
Electronics Forum | Tue May 13 08:26:29 EDT 2008 | davef
First, on your reflow temperature comment: The 183*C focus for reflow recipes for tin-lead solder is a falicy. If you held a recipe for tin-lead solder at 183*C peak, it would never reflow. Recipes for tin-lead solder need to be at liquidus plus 20*C
Electronics Forum | Wed Jul 31 08:23:49 EDT 2002 | mcm4me
221C). 2D vision can very effectively detect % pad coverage, I use it on my DEK and this customer has an MPM which I also believe to be capable. Here is another fact, when the customer uses Brand X solder paste the defects due to what they call pad
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