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Mechanical Hole Cleaning

IP.com Disclosure Number: IPCOM000087691D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Klauser, HE: AUTHOR

Abstract

A problem is often encountered in cleaning abrasive slurry trapped in small, high aspect ratio through-holes of a printed-circuit board, which, if not removed, will clog the holes. One technique has been to vapor-blast the holes, followed by a spray rinse step and then immediately, while the panel is still wet, subjecting the holes to clear water flushing at a pressure of about 40 pounds per square inch. However, this process is slow and requires physical contact between the panel and a suitable baffle.

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Mechanical Hole Cleaning

A problem is often encountered in cleaning abrasive slurry trapped in small, high aspect ratio through-holes of a printed-circuit board, which, if not removed, will clog the holes. One technique has been to vapor-blast the holes, followed by a spray rinse step and then immediately, while the panel is still wet, subjecting the holes to clear water flushing at a pressure of about 40 pounds per square inch. However, this process is slow and requires physical contact between the panel and a suitable baffle.

This difficulty is overcome using a vapor-blasting step with an abrasive slurry which is followed by a second vapor-blasting step in a separate chamber, but with clean water and no abrasive. The air/water mist, directed at the panel surface, removes the residual slurry from the surface and from the high aspect ratio holes. It is important that the panel surface not be allowed to dry out between the two vapor-blasting steps. It is desirable to use a jet of water/air mist which is "softer" than a high pressure water jet so that it will not delaminate the panel.

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