Electronics Forum | Fri May 15 10:04:59 EDT 2009 | aj
Hi all, Is there any standard for percentage voiding on the center thermal pad on a QFN? We use the dot matrix array for paste to allow for outgassing etc, but we have had a couple of xray inspection "fails" for voiding on this pad , in or around 3
Electronics Forum | Thu Oct 11 13:10:04 EDT 2012 | anvil1021
We are experimenting with void control in reflow and have had pretty good luck for the most part in attaining Class lll IPC spec. but we have seen a sudden increase in voiding on a specific product and I was wondering if anyone has seen this extreme
Electronics Forum | Wed Mar 15 12:39:24 EDT 2017 | cyber_wolf
Customer precedes standard, but customer must be educated and informed on what is achievable with their design and what is accepted as industry standard practice. My guess is that the negative effect of those voids is negligible. {Voids at the sold
Electronics Forum | Sun Jan 05 20:10:16 EST 2020 | sssamw
Yes, you may need tell us how the PCB designed, how it re-flow(even it's Indium voiding formula), how stencil is. The void ratio means area ratio, not diameter ratio, so you need calculate it. If you have high ratio void, show its picture.
Electronics Forum | Tue Jun 16 19:41:46 EDT 2020 | emeto
Voids form mainly two ways. 1. Contamination - due PCB pads/part leads oxidation, wetting on the pad is bad forming void(these are usually borders with SMT pad - peripheral) 2. Process formed. These are in the center of the solder joint - could n
Electronics Forum | Mon Jan 22 22:37:27 EST 2001 | davef
50 ppm oxygen was on half joints reflowed in air. 3d Human factors PCB pad cleanliness: Handling of bare board pads creates excessive voiding. Print rejection: Cleaning of OSP pads with acetone or isopropanol increases voiding.
Electronics Forum | Wed Feb 09 06:35:18 EST 2000 | Mark Williams
Hi We use 2 criteria... maximum void size is 10% of the solderable surface and a maximum area of voids of 10% of the maximum cross-sectional area of the ball. Any views Mark
Electronics Forum | Wed Oct 03 17:10:32 EDT 2001 | davef
Your component is probably EPTSSOP [Exposed Pad Thin Shrink Small Outline Package]. We had a thread on EPTSSOP a couple of months ago. [Check the fine SMTnet Archives for background.] You�re correct that voids in the solder on the exposed pad [rea
Electronics Forum | Mon Mar 15 10:43:06 EST 1999 | grevald
After switching from No-clean flux to Water soluble (Kester)we encountered voids problem (X-ray and microsectioning). Reducing the apperture sizes made the voids smaller but did not eliminate them. So we had to go back to No-clean. Any idea why voids
Electronics Forum | Thu Jan 14 23:49:00 EST 1999 | Wirat Sriamonkitkul
I saw the problem of void in solder bump or in lead less component or some BGA. But I didn't have standard specification of that void is accept or reject? Do any body have the better idea or suggestion of the criteria ? Thank you, Wirat S. / Jan 15
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