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Electrolytic removal of epoxy molding compound on transistor packages using copper leadframes

I am a new TO-220 transistor package molding engineer and I would like to replace our existing wet deflashing process (sand blasting using glass beads to blast off excess mold compounds/flashes/resin-bleeds (epoxy molding compound) on the surface of the bare-copper (non-plated) leadframe heatsink and leads) with a new electrolitic process in order to eliminate deflashing process' dust and surface finish effects and to utilize our existing plating line.
I would like to ask some help on the chemicals needed and some processing operations, tips, etc.. if possible. Thanks a lot.

Antonio Dimataga
electronics - Shanwei, Guangdong, China
2005

There is no electrolytic process that will do anything to a dielectric material such as epoxy. Look into potent solvents.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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2005

There has been electrolytic flash removal chemistries for many years.The process requires high pressure water blast
after electrolytic process.

This process is used in most continuous cut strip plating machines.

Chemistry is non-toxic and is not a solvent.

Louis Hirbour
- Anaheim, California

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Mr. Hirbour,
Does the current flow through the resin, or does it flow over the surface? Please enlighten me a little as I cannot see how this could happen. Thks.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

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Dear Mr. Hirbour,
You are rignt. And I am now sourcing for a water jet deflash equipment to blash off the flashes/resin bleeds after the electrolytic process. Am now sourcing for the electrolytic chemicals too.

Antonio Ybanez Dimataga
- Shanwei, Guangdong, China
2005

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2005

Hi All,

Actually Electrolytic Deflashing is good but some certain material cannot be good, as it will cause delamination especially on Ag plated leads. I've done a lot of study and evaluation on this but until we found out that Electrolytic deflash is one cause of delamination.

Regards,

Irvy Cane Boltron
- Singapore

Agreed Mr. Irvy Cane Boltron mentioned of phenomenon that CD relative to degrade adhesion performance between EMC and metal especially for the condition of package with moisture content that chemical bond may be groken during ED of current passing and electrolysis of water ( internal moisture ) with outgasing get gap as delamination.

C C Chen
- KaoHsiung
2006

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2007

We have similar problem with TO220 deflashing process, the flash is hard to remove during deflash process, how to solve it? please advise.
Regards
IMAGE

Yuxinglong
Technic (Suzhou) - Suzhou, Jiangsu, China

Does anyone have any articles, references etc showing that electrolytic deflash causes delamination or loss of adhesion between silver plated leadframe and epoxy

Alastair Trigg
IME - Singapore, Singapore
October 14, 2008