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Molded Printed Circuits

IP.com Disclosure Number: IPCOM000092980D
Original Publication Date: 1967-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Kollmeier, X: AUTHOR [+2]

Abstract

This method provides printed conductors molded into a plastic substrate. The conductor configuration has improved mechanical bonding to the substrate. Copper foil 20 is plated or clad with nickel 22, the foil and plating being of the order of 1.2 mil and 0.3 - 0.5 mil units thick, respectively. Photolithographic techniques are employed in step 1 to inscribe a desired pattern on copper 20. The circuit or pattern is etched through to expose nickel 22. A typical etchant for the etching process is chromic sulfuric acid mixture.

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Molded Printed Circuits

This method provides printed conductors molded into a plastic substrate. The conductor configuration has improved mechanical bonding to the substrate. Copper foil 20 is plated or clad with nickel 22, the foil and plating being of the order of 1.2 mil and 0.3 - 0.5 mil units thick, respectively. Photolithographic techniques are employed in step 1 to inscribe a desired pattern on copper 20. The circuit or pattern is etched through to expose nickel 22. A typical etchant for the etching process is chromic sulfuric acid mixture.

After etching, exposed nickel 22 is suitably cleaned prior to deposition of plated gold 24, as shown in step 3. Gold 24 is deposited to a thickness of the order of .3 - 1 mil. The gold deposition assumes a horseshoe-shaped configuration bounded by surrounding copper 20. The photolithographic resist is removed from copper 20 and nickel 22. Afterwards, copper 20 is completely dissolved by a suitable etchant which does not attack nickel or gold.

A satisfactory etchant is chromic sulfuric acid mixture.

The pattern or circuit is molded into plastic material 26, for example, phenolic plastic or silicone plastic, as shown in step 4. Afterwards, the nickel carrier is dissolved exposing the gold plated conductor. The horseshoe configuration of the gold conductor improves the mechanical bonding to plastic substrate 26.

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