Method for Manufacturing Substrates Containing Tapered Holes
Original Publication Date: 1985-Jul-01
Included in the Prior Art Database: 2005-Feb-19
The use of electroless gold or other non-reactive metals eliminates rim voids at the top of tapered holes containing flush pins in a ¼" flush pin memory module. The flush pin memory module 1 contains holes 2 that are countersunk. After metallizing the surface 4, photoresist is applied, exposed, and developed to define the circuitry for the module 1. There has been difficulty providing continuity between the circuit line 5 and the inside of the hole 2 because the resist tends to thin at the countersink 3 causing the metal to etch and thus cause an open between the circuit line 5 and the inside of the countersink 3. A method of solving this problem is as follows: 1. After metallization, apply photoresist. 2. Expose and develop resist such that the doughnut around the hole and about 10 mils of the conductor line are opened.