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Epoxy for solder mask touch up


CL

#31263

Epoxy for solder mask touch up | 8 November, 2004

Good Day Everyone,

I have a BGA rework that has some chipped/damaged solder mask that will need to be repaired prior to BGA replacement. I was wondering what materials are being used in the industry for this type of application. Any help would be greatly appreciated.

Thanks In Advance

Chris

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#31265

Epoxy for solder mask touch up | 8 November, 2004

You need to cover the chipped areas with a protectant coating, like epoxy. Look here:http://www.circuittechctr.com/products/115-1322.shtml

We have no relationship, nor receive benefit from the company referenced above.

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RDR

#31267

Epoxy for solder mask touch up | 8 November, 2004

We usually get some mask material from our board house. It cures with heat so it works really well in our applications. Be wary of the "overcoat pens" they don't seem to hold up under heat and thre solder will flow right underneath it during BGA attach.

Russ

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#31272

Epoxy for solder mask touch up | 8 November, 2004

Russ:

On "usually get some mask material from our board house. It cures with heat so it works really well in our applications.": We're unsure about the type of mask that you are using, but be careful [we used to do this, also]: * Final cure of the LPI solder mask: 310*F for 45 minutes * From spec, cure of SR1000 solder mask: 300*F for 60 minutes

If you're not using the recommended cure, all bets are off on the effectiveness of the mask. The rule of thumb is: * Any mask defects that affect the assembly or field use are not acceptable. * Rework to these conditions shall meet the solder mask performance requirements for dimensional, mechanical, chemical, and dielectric.

On "Be wary of the 'overcoat pens'": We agree. They're like my daughter's magic markers.

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RDR

#31273

Epoxy for solder mask touch up | 8 November, 2004

Looks like we have been running the cure a little short (but only by about 44 min). I need to check if elevated temp shortens cure time to 1 min. at 700F!

Thanks Dave, much appreciated

Russ

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RDR

#31274

Epoxy for solder mask touch up | 9 November, 2004

I guess i might want to throw this in for future reference.

After speaking with our board supplier he states that this mask is fully cured when it reaches approximately 180C. I beleive this since we usually probe the repaired area after putting the heat gun to it. it is well adhered and hard.

This stuff is made or distributed by Fred LeVine services P/N LPI-G2 I have no idea how to get a hold of this place however.

Russ

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