Electronics Forum | Tue Sep 14 14:22:11 EDT 2010 | grahamcooper22
If the HASL was poor quality and very thin you would find this defect....but you would expect to see it on more pads also. Also, you'd expect to see your solder from your solder paste either dewetted on the pad or reflowed onto the BGA sphere making
Electronics Forum | Mon Jan 29 06:44:59 EST 2001 | Scott B
I have recently come across a device which has a palladium over nickel finish which when soldered shows evidence of poor wetting to the lead ( i.e. a wetting angle greater than 90�) about three quarters of the way up the side of lead. This is only vi
Electronics Forum | Tue Sep 14 14:07:45 EDT 2010 | grahamcooper22
Hi Gani, HASL is normally very good for solderability providing there is a good consistent coating of HASL on the pcb pad. But it is not unusual to have a very thin coating of HASL on the pad and this is poor for solderability. You then have tin/copp
Electronics Forum | Thu Sep 02 09:51:53 EDT 2004 | davef
We see latches from some suppliers that just are not solderable. Usually the nickel plate on the latch is poor, allowing the nickel to corrode, and requiring a more active flux [if you're lucky]. But lots of times, you end-up with partial wetting,
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 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 | 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 | Wed Nov 06 19:03:33 EST 2002 | broncos
If you are certain that reflow process is good, I would suggest starting checking the following: 1. Check to see if leads / pads are contaminated or oxidized. However, this usually results poor solder quality throughout the board. 2. Check the amou
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 Nov 07 09:56:26 EST 2002 | bpan
Thanks for the ideas guys. My QC inspector can take a pick and move the back part of the lead....even though the front of the lead is soldered enough to hold. There is SOME NOT ALL areas where there is no solder on the curved portion of the lead.The
