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Technique of PTH reliability improvement

IP.com Disclosure Number: IPCOM000013609D
Original Publication Date: 2001-Jul-11
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Abstract

Disclosed is a method to improve the reliability of insulation resistance among Plated Through Holes (PTH). When the pitch of PTH becomes small, the insulation resistance decreases, too, and the product reliability becomes worse accordingly. Some chemicals filter into the fiberglass which composes an insulation layer in the printed circuit board, and the wall thickness among PTHs becomes much thinner. And the phenomenon that insulation deteriorates electrically happens after Copper Plating on PTHs. In consideration of the mechanism of the insulation deterioration done so, a film forms an insulation layer newly using a suitable resin covered on the PTH wall, and the insulation of the PTH side wall is maintained high, and this invention is how to form PTH which has the high reliability which isn't influenced by the pitch of PTH. This invention is consist of the following process through (A) to (E). (A) To remove smear inside the holes by the chemicals in the circuit board after the holes formation by drilling.

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Technique of PTH reliability improvement

   Disclosed is a method to improve the reliability of insulation resistance among Plated Through Holes (PTH).

When the pitch of PTH becomes small, the insulation resistance decreases, too, and the product reliability becomes worse accordingly. Some chemicals filter into the fiberglass which composes an insulation layer in the printed circuit board, and the wall thickness among PTHs becomes much thinner. And the phenomenon that insulation deteriorates electrically happens after Copper Plating on PTHs. In consideration of the mechanism of the insulation deterioration done so, a film forms an insulation layer newly using a suitable resin covered on the PTH wall, and the insulation of the PTH side wall is maintained high, and this invention is how to form PTH which has the high reliability which isn't influenced by the pitch of PTH.

This invention is consist of the following process through (A) to (E).
(A) To remove smear inside the holes by the chemicals in the circuit board after the holes formation by drilling.
(B) To apply tape-masking on one side of the circuit board that holes are formed.
(C) To apply the resin (Photo-sensitive: Negative type) inside the holes by using Electro-statistic Coating mehtod for the circuit board with tape-masking.
(D) To remove tape-masking, and to expose the resin inside the holes from the side which is removed Tape-masking, and to develop. The resin is left only inside PTH after the development. T...