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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