Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.




Voids | 24 November, 2004


Has anyone done this? X-ray a populated PCB and found voids on chips and some IC solder joints? Is this kind of screening acceptable? I got a PCB with this problem and not ruling out paste, profile and contamination issues. Please Help as it seems crazy to X-ray the whole PWB and look for voids specially on non-BGA components.


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Voids | 25 November, 2004

See, you never should have purchased that xray machine. Look at the mess you've got yourself into now. ;-)

Enough recrimination. What you're seeing is not surprising, not that that makes it correct. If you're seeing voids something is wrong with your process or materials [or both]. In most cases, it's a process indicator. So, you need the buy-off on the acceptability of void on a case-by-case basis. [And then take what ever corrective action your quality tribe dictates.]

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Voids | 28 November, 2004

Hi Guy, I see them frequently. Usually, if I have voids on my BGA's, I'll have them on my passives as well as at leaded device solder joints. They run rampant through the entire assembly. For me, it's a function of my profile. I only have a 4 zone oven in my lab and I'm running an RMA paste. These both make things tough on me but I'll stop my whining now. Dave is right, voids are certainly a process indicator but whether or not they're detrimental would take an awful lot of time and money.

regards, justin

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Voids | 3 December, 2004

Dreamsniper, We would need much more details about your process to help you to determine the source of voids. Type of paste, how long you leave your paste on stencil, your relative humidity, reflow profile, type of oven, oven environment (N2?) and so on. All those above can contribute to voiding in solder joints. As it was said they are usually a process indicator unless they exceed the spec limit. (IPC-7095A for BGA's)

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Voids | 3 December, 2004

The voids are between the interface of the pad and the solder joint of component chips. I have a good thermal profile and this problem occured only on certain product so since we have some common components, component termination contamination is no longer an issue. And since we do not have this on other products solder paste issue is not an issue as well. PWB pad contamination is what I suspect. I'm using a WS709 Water Soluble Flux and a 5 Zone Heller Oven. I read a champagne void article and from my understanding this term is for BGA solder joint and not for 0603, 0805 components. I've been told that I have champagne voids on my components.

thanks again for ur assistance regards,

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Voids | 3 December, 2004

Voids are quite common. You just need to make sure that it is not excessive per your assembly criteria.

Take a look at a D-pak under X-ray.

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Voids | 13 December, 2004

I run a D.O.E. and print different water soluble pastes on the same board by mini-stencil and reflow on same profile. WS709 is one of them but Indium6.2 shown less and no void then WS709. P.S.: profile may affect the result.

Do U have Via in pad? What is the Fab finish? Bake the parts and fab may help little bit.....

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