correct me if I am wrong. there are ESD kapton tapes...jk
On Oct 11, 2007, at 3:37 PM, Barry Gallegos wrote:
> Richard,
> Many thanks. I did not know that. I will pass this on to my group.
>
> Barry.
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: Thursday, October 11, 2007 1:35 PM
> To: [log in to unmask]
> Subject: Re: [TN] Shielding for BGA rework
>
> Finally, something I know a little bit about.
> I have learned that Kapton tape should never be used as a masking tape
> on circuit boards for rework, or for any other purpose either. What I
> did not know is that Kapton (polyamide) tape generates a gigantic ESD
> charge (greater than 5kv) when pulled off of the reel, and about 500v
> when pulled off of the circuit board. This was shown to me by an ESD
> engineer.
> I also know that polyamide tape is an excellent heat conductor (not
> insulator) and does not work very well as a maskant to form a
> barrier to
> protect adjacent or surrounding components when performing hot gas
> rework. It does work well to hold a thermocouple to the board, and the
> actual temperature drop through the polyamide tape is exactly 1 degree
> C., so it is OK to use for that, but only on a bare PWB or a scrap
> board. After the display by the ESD consultant, I now cringe when I go
> into factories and see the polyamide tape on workbenches. I know there
> are dispensers that supposedly remove the charge, but how about
> when the
> tape is removed from the board?
>
> There are masking tapes made just for shielding of other components
> when
> doing rework. They look just like the masking tape you use when
> painting, except they are high-temperature tape and are
> dissipative. Two
> companies that make them are Intertape Corp. and 3M. Intertape's
> p.n. is
> T-33-1 PRT054. I do not have the 3M tape part number, but I am sure
> your
> local 3m rep would be glad to take you out to lunch and give you that
> info and a whole bunch more. These tapes do have a higher adhesive
> content and can leave some residue on the components, but an alcohol
> brushing cleans it off completely.
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
> Sent: Thursday, October 11, 2007 2:06 PM
> To: [log in to unmask]
> Subject: [TN] Shielding for BGA rework
>
> Hello again,
> Does anyone use any shielding for adjacent components and PCB material
> when they are reworking a BGA, in order to minimize the heat seen by
> those areas in close proximity?
>
> If so, what do you use? Is there a commercially available product, or
> do you just make your own as needed (someone here said they had seen
> foil and kapton tape used elsewhere).
>
> Thanks much, as always.
> Genny.
>
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