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Hair Line Solder Short at PTH Connector

Dhanish

#33701

Hair Line Solder Short at PTH Connector | 13 April, 2005

In production,we are seeing high defect for Hair Line Solder Shorts for PTH connector and the Hair Line is too tiny that X-Ray and ICT could not detect.Any suggestion on how we can resolve or at least detect this upfront.

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#33703

Hair Line Solder Short at PTH Connector | 14 April, 2005

What is the pitch of the device and what type of flux are you using? You may eridicate the fault by using a more active flux. I assume you are flowsoldering the device as opposed to paste in hole. Do you have an air knife? If so, you could try experimenting with it. Too low a pressure and it might not be doing it's job, but beware that too high a pressure might actually cause shorts!

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pr

#33709

Hair Line Solder Short at PTH Connector | 14 April, 2005

What kind of wave are you using? Is this an old job and a new problem? Sounds like dross shorting to me, Make sure the wave is flowing over the back plate (at least when the board hits it).

good luck, pr

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#33711

Hair Line Solder Short at PTH Connector | 14 April, 2005

All possible causes aside, how can a dead short pass your ICT unless the connector is not probed.

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KEN

#33732

Hair Line Solder Short at PTH Connector | 14 April, 2005

What side is the short occuring on. Topside or bottom (solder) side?

2. Pitch of hole pattern = ? 3. Your x-ray may not have the resolution or DSP capable of detecting this defect.

How does your profile look? Is this a true short or the result called "cob-webbing" "spider-webbs" etc.

What type of fluxer are you using? Flux type?

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Dhanish

#33736

Hair Line Solder Short at PTH Connector | 15 April, 2005

The biggest problem I am having is the X-Ray and ICT could not detect this shorts.ICT could not detect because onboard measurement shows Zero even without the Hair line shorts.With Hairline there is no difference in the impedance value for ICT to fail.

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#33738

Hair Line Solder Short at PTH Connector | 15 April, 2005

Dhanish,

If I understand correct your ICT doesn't detect shorts and only measures capacitive and resistive values. The webbing as Ken mentioned would have a resistance because this is caused by a lack of flux and the web is mainly tin oxide, which wouldn't measure zero. Have you magnified these shorts if they are like needles stuck to the board? I've seen this phenomenon in leaded soldering with cu levels (if I remember well) close to 2%. These levels can be reached when soldering osp/ Cu boards on a day to day bases. A high copper content forms Sn/Cu needles in the solder causing random shorts and the biggest problem is not on every board or every day.

Are you using leaded or lead free solder? lead free will dissolve Cu a lot faster.

Pat

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KEN

#33749

Hair Line Solder Short at PTH Connector | 16 April, 2005

What about electo migration? I had (what apears to be) the exact same problem you describe. X-ray and ICT fails to detect micro shorts. However, in our test, the bench functional test would show a current overload. In some cases the electro migrtion was so thin it would vaporize like a fuse. A Self healing problem if you will...

EDX revealed high concentrations of silver between electrodes (interconnects). The root cause was DI water under the BGA devices during ICT test.

Hope this helps

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greg york

#33805

Hair Line Solder Short at PTH Connector | 20 April, 2005

Try a rosin flux this has solved it for me on numerous occasions, no need to use heavy rosin only around 4% total solids so rosin around 1.5% is sufficient. It is down to the plasticizers which are tacky coming out of the resist. The rosin is an immediate fix.One customer couldonly pick these up in ICT and they were very small harline shorts caused by the oily/waxy tacky residue holding onto the solder and not letting it drain off the PCB properly. And yes it gets definately worse with Lead Free as the stresses and heat are more for the resist to handle Hope it helps

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#33823

Hair Line Solder Short at PTH Connector | 21 April, 2005

Hi Y'all

It would be valuable to the users of this forum to get a response from the original poster about his/her findings and solutions. It usually starts with the post of a problem, then opinions and experiences get exchanged but we never see a conclusive results or solution to the original problem. Posting the solution or findings from the original thread poster would add tremendous value to this already great web site.

Pat

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RDR

#33829

Hair Line Solder Short at PTH Connector | 21 April, 2005

Definitely would help when doing the search's. I always find a numerous amount of suggestions but you're right, you never know if anything worked!

Russ

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#33832

Hair Line Solder Short at PTH Connector | 21 April, 2005

Thanks Russ I must have caught you on a good day I'm not used to see you agree with me.

Just kidding (couldn't resist)

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