Electronics Forum | Mon Oct 20 15:24:52 EDT 2008 | davef
During reflow soldering, sometimes via fill with solder leaving the solder connection starved. Questions are: * Specifically, what is the problem you see? * Do the defective pads show that solder has melted in a uniform fashion? * How do the tempera
Electronics Forum | Mon Oct 20 21:57:58 EDT 2008 | jdt13
The problem that I see is the pads not soldered and I can see on the X-Ray the solder on the pad after reflow, and yes the solder has melted in a uniform fashion, I have not measured the diference of temperatures in each pad of the PCB, the size is a
Electronics Forum | Mon Oct 20 07:29:17 EDT 2008 | hussman
I assume you mean soldered and not welded. If the one pad that is having problems has a via hole next to it, it probably has more copper around it. Try running a hotter profile.
Electronics Forum | Sun Oct 19 15:02:10 EDT 2008 | Jdt13
We are having some issues with a RF PCB aprox 1" x 1". The pads are in the bottom of the PCB and it goes on the Top side of the mother board the pads of the RF board are like a BGA (square pads)and we have troubles to make the proper welding in the
Electronics Forum | Wed Sep 05 08:50:04 EDT 2001 | davef
No arument with others comments about moisture, but taking a different tact, consider that the volitle elements of the solder paste disppear as a function of the amount of time the paste is out of the container. [Maybe as a function of solder paste
Electronics Forum | Mon Sep 03 08:56:26 EDT 2001 | henriksn
Hi everyone, I work in a development firm, that has a small prototype department. We have recently invested in a small automatic SMD pick&place machine. When mounting over 100 different components, the machine runs out of feedercapacity, and the res
Electronics Forum | Tue Sep 04 09:12:35 EDT 2001 | caldon
Moisture would be my main concern. Even though components are plastic, they can absorb moisture. Moisture is also detrimental to the the solder itself. The water droplets that are left behind (evaporated even) could cause problems (i.e. chlorides).
Electronics Forum | Tue Sep 18 10:43:59 EDT 2001 | henriksn
Hi, And thanks for the advice. I have tried your method now, and it seems to be working. By visual inspection with a microscope it was almost impossible to tell the differrence between the pcb that had been in the frig and the pcb's that were normal
Electronics Forum | Tue Sep 04 11:09:25 EDT 2001 | blnorman
As the others have stated, moisture is the killer. You have to be sure no moisture is allowed to get to the paste. If it does, you'll get solderballs. I would suggest not using a vacuum. The solvents and other volatile components of the flux will
Electronics Forum | Wed Sep 26 14:58:46 EDT 2001 | bobm
i have stored boards in the refrigerator in side a tray (with a lid) for 2 days and still had them reflow with no problems. i don't know if i would go any longer than that. i would not put any qfp's or any other device that is moisture sensative dev
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