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Delamination / Measling

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MGL

#57532

Delamination / Measling | 8 December, 2008

We are experiencing delamination / measling on card we have been running for years. No change in process. Same equipment, profiles etc. The weird thing is we are experiencing it on pwbs from different mfgs and different processes (reflow, wave, selective and also hand soldering) In 11 years no problems in 2 or 3 months a lot of issues. Anyone else seeing issues?

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#57537

Delamination / Measling | 8 December, 2008

Hi MGL,

Couple things to ask, have the boards recently been changed to Rohs builds? STD FR4 to High TD Laminate.

Check the stack-up the board houses are using.

Just about all Rohs laminate has Resin starvation issues when used in single ply constructions and most shops have had to change the stack-ups of the product from 1 ply pre-preg material to 2 ply pre-preg to combat this Resin issue.

The Laminate suppliers to the industry have not been very good help in this issue to reduce Delamination or in helping manufactures with suggested Stack-ups for their lead free materials.

And it has been occuring throughout all material brands, Isola, Nelco, Iteq, TUC and Nan ya just to name a few.

I would ask your board shop for the following Info.

1) What brand of material was used. 2) What is the construction stack-up they used. 3) What TG / TD was the material that was used.

Other things to look at are, Moisture - the Rohs material absorbs moisture easier that Std. FR4 material. Pre-baking the bare board prior to assembling may be needed to your process. You should not have to do this but I have quite a few of my CM Customers that do this as a precaution.

The use of Lead free products & materials has been an ongoing battle for all parties, Manufacturing & Assembly.

Search this Forum for more info on Delam, their is plenty of it on here.

Good luck,

Boardhouse

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MGL

#57540

Delamination / Measling | 8 December, 2008

Board House, Thank you for the info. We are baking 6 hours at 250F prior to processing. We are a military contract house that has always baked and have never had issues until recently. I appreciate the info. We are sending a team on the road to visit the board houses and that gives us some questions to ask. Thanks - Matt

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#57594

Delamination / Measling | 13 December, 2008

If you're military then you're probably just needing standard 130Tg FR4 and tin-lead finish. I would check two things:

1. Bake temperature: Isola recommends 300F for 4 hours to drive moisture out. Lower baking temperatures do not require a linear extension of time, but rather exponentially higher.

2. If you are requiring at higher Tg, then it is most likely that your board house defaulted to a phenolic material that is not only a higher Tg, but also lead free capable. Like Boardhouse mentioned, these materials are like sponges that can trap moisture. Either you need them to switch back to dicy cured materials or follow the pre-bake recommendations.

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