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Via Filling Method for Injection Molded Boards

IP.com Disclosure Number: IPCOM000036685D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Ameen, JG: AUTHOR [+5]

Abstract

Disclosed is a process that provides a low cost metallized through- hole for an injection molded board.

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Via Filling Method for Injection Molded Boards

Disclosed is a process that provides a low cost metallized through- hole for an injection molded board.

There are a variety of techniques for metallizing both sides of an injection molded (thermoplastic) board. It is far more difficult to provide a "plated through hole" in this board. Although photolithographic and plating techniques exist, they are too expensive for this technology. The following is proposed as a low cost method to achieve a metallized via: 1) Laminate copper to both sides of the injection molded board. Personalize the copper being sure that Cu is left intact over the holes. (It may be possible to buy a roll of the desired circuits ready for lamination (similar to a lead frame) if the circuitry is simple enough.) 2) Using a punch (Fig. 1A), cut 3/4 of the copper over the holes and fold down the balance of the uncut copper into the holes. Do this from both sides, so that the diameters of the Cu holes are lying in the vias. 3) Screen and cure a solder mask as usual.
4) Insert components as usual. 5) Wave solder components. Solder will fill the vias by solder bridging in the vias that have no components (Fig. 1B). (Solder will easily fill the vias having pins through them due to this same bridging action.)

What results is a low cost board with metallized through-holes.

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