Electronics Forum | Wed Jul 31 17:35:16 EDT 2002 | davef
* Finally, when soldered by hand, do the problem pads take solder? Yes, the XRF analysis will be interesting.
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 | Mon May 22 18:19:29 EDT 2006 | Steve
I have read some threads about poor wetting on palladium-silver (Pd-Ag) coated components. I followed the suggestions, but I am still having a problem. The part is an 0603 chip type (Vishay varistor). The Process: solder paste is lead-free Alpha Met
Electronics Forum | Tue May 23 09:27:37 EDT 2006 | Steve
Sorry I misled you. The PCB pads are wetting, but there is no fillet being formed. After reflow, it looks as though no paste was put down on the pads; however the paste print is fine. All other components solder real nice, it's only the Pd-Ag parts t
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 12:15:15 EDT 2002 | Rick Lathrop
Hi Dave, The paste applied to the board ends up on the tombstone. The pad has a thin covering of solder most of the time, this is why I think they call it a dewet. Occasionally the pad shows some areas of gold and very rarely are some pads not wet at
Electronics Forum | Thu May 25 08:00:49 EDT 2006 | davef
The warmest spot you measure on the board is the bare laminate. It will be 10*C hotter than a solder connection.
Electronics Forum | Tue May 23 09:50:37 EDT 2006 | flipit
They work well in silver conductive epoxy in hybrid applications. They are very poor in no clean applications. They don't work that well in OA solder paste either. Used them once in OA paste and in a nitrogen. They looked just fine. Solder to Pd
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 23 09:01:48 EDT 2006 | russ
Seems as though the problem is with PCB and not component? "Solder does not wet to pads, wets to component" What is your board finish? Russ
