solder ball after reflow owen

Hi Any,

This is from an earlies thread "Solder Ball After Reflow Process".

Date: August 16, 2006 01:52 PM Author: Russ Subject: Solder Ball After Reflow Process

Oven settings are meaningless here. What does the board see? It is the paste we are concerned about not what the heaters are running at hehe.

These solder balls are at the end of pad, which end? under the part or away from the part.

I believe you may have stencil issue myself, if profile is good.

common causes of balls are:

ramp rate too fast (splattering appearance) print misaligned (splattering appearance) bad paste either lot or type. (splattering or formed ball appearance) bad stencil design (could be single ball or splatter) poor paste handling and storage - excess moisture in paste

why are you worried anyway? after wash they should be gone since it is water soluble, if they are not gone then you also have a cleaning prob.

So get us the profile data such as max ramp slope, TAL, Max temp, and soak paramaters (how long at what temp)

Hope this helps, solder balls can be controlled we just need to see what you are doing. Russ

(http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=43354)

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Date: August 18, 2006 07:42 AM Author: Amol Kane Subject: Solder Ball After Reflow Process

Hi Russ, Can you please clarify on what you mean by "after wash they should be gone since it is water soluble,".....the flux would be water soluble or otherwise, how does that relate to solder balls being removed by cleaning?...i can see them being removed by the force of the cleaning chemistry, but cannot see how the flux type will affect their ability to be removed.

(http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=43403)

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Date: August 18, 2006 09:07 AM Author: Russ Subject: Solder Ball After Reflow Process

pretty much menaing Amol, that the balls are stuck to the board by flux and when you wash the flux the balls go away with it. If yopu are running no clean, then there will be no cleaning step and the balls will remain since the flux is basically untouched.

Did this help?

Russ

(http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=43406)

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Date: August 16, 2006 02:30 PM Author: Steve Thomas Subject: Solder Ball After Reflow Process

What do you mean by "near the pad of SMT component"? The end of the pad, side of the pad, or perhaps adjacent to the part body, between terminations? One solder ball per component, or many, perhaps of different sizes?

(http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=43355)

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Date: August 18, 2006 12:23 AM Author: Umar Subject: Solder Ball After Reflow Process

Hi SWAG/Rush/Steve,

Thanks for your response, Currently I am running with 811 lead paste. Actually this problem not only effect for one assy. I got 700 models runing at my company, but almost 50% of the model I have problem with solder balls issue.

The location of the balls is sometimes is near by of the part (is like splattering),end of the pad and even some is the sid eof the pad.

All my product is different PCB thickness, the minimum thickness is 4 layer and max thickness is 14 layer.

Yup correct, since my paste is water soluble the solder balls is easily removed at cleaning stage. but that's not to solved the problem. The only way to solved the problem is to kill the actual root cause of the problem. As I attend some seminar" Do it Right The First Time" and do prevent before happen.

Then right now I don't know what's the actual root cause of the solder balls.

Your kindly response to thismatter is very much appreciate.

(http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=43398)

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Date: August 18, 2006 07:37 AM Author: Chunks Subject: Solder Ball After Reflow Process

Hi Umar,

I believe you either are over printing these pads or the alignment of board and stencil may be off. Check your print right after your screen printer to verify either. If you are not over printing and your paste alignment is spot on, then you check after placement. Your placement machine may be over driving the part down so much it skews the paste off the pads - which may cause balling. Do you have an operator before reflow oven? If so, some believe they can place a part better than the machine and move the part around a bit - which could cause balling. If all above is good, then it must be your oven and it's time to reprofile.

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