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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


solder balls

leon

#28433

solder balls | 6 May, 2004

iam having trouble with solder balls around 1206 caps and resistors, have used different pastes changed oven profiles can any advise something else

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Bryan She

#28436

solder balls | 6 May, 2004

Modify your stencil aperture shape...reduce the solder paste deposited on pad,will reduce the solder balls.Be sure your reflow profile are good before doing this.rising slope is very important. This is my opinion.thanks. Bryan

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Lloydy

#28498

solder balls | 9 May, 2004

Try using the wendy-house style on the specififc area's where you have solder balling. It's not always a good idea to do a global reduction to all apperatures.

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steve davis

#28520

solder balls | 10 May, 2004

Just curious what stencil company are you currently using?

What style of aperture are you using for the componet?

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Erhan

#28538

solder balls | 11 May, 2004

It's been 10 years since I started to use this editing method but never knew that it was called wendy-house style. :-)

This is most probably the answer you're looking for if you're only having problems around the 1206 types. For QFPs, I used to reduce at least 1 mil from each edge, using trapezoidal apertures. One designer had designed the QFP 240 pads 14x100, I used to order the hole a 12x90 centered. Used Nitrogen in the reflow zones though.

Hope these help.

Erhan

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#28546

solder balls | 11 May, 2004

Solder ball problems has to be one of the most popular topics on SMTnet. There is hundreds of postings on the topic in the fine SMTnet Archives. For instance: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=15669

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#28553

solder balls | 12 May, 2004

Lets make it easy on the poor guy, some are correct, check you profile but remember one thing most do not apply, it is important to match the type of paste you are using with the style of oven and configuration. send a direct email and I will give some great tools of the trade to help you do just that, free software.... then simply make sure the pad layout base on the component size is not matched, if the paste is getting under the body of the component, thermal transfer will not be the same, and you will have solderballs, escpecially if using VOC free paste. if this is not the case, you need to know how to get the most robust profile for the paste you are using....lots of pro's out there, becareful what you do....

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