Browse Prior Art Database

Method for Selective Plating and Etching Using Resistive Heating

IP.com Disclosure Number: IPCOM000052436D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 52K

Publishing Venue

IBM

Related People

Melcher, RL: AUTHOR [+2]

Abstract

A method is described which makes possible the selective plating and/o etching of metal lines on chips, cards, boards and ceramics. Uses are foreseen in the personalization and repair of chips and packages for electronic circuitry. The method makes use of the existence of relatively high resistance segments of otherwise highly conducting lines. An electric current locally heats the high resistance segments causing greatly enhanced plating rates.

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Method for Selective Plating and Etching Using Resistive Heating

A method is described which makes possible the selective plating and/o etching of metal lines on chips, cards, boards and ceramics. Uses are foreseen in the personalization and repair of chips and packages for electronic circuitry. The method makes use of the existence of relatively high resistance segments of otherwise highly conducting lines. An electric current locally heats the high resistance segments causing greatly enhanced plating rates.

A method is described in Applied Physics Letters 35, 651-653 (November 1979) by R. von Gutfeld, et al, for selectively enhancing electro and electroless plating and etching using focused laser light to locally heat the cathode, causing local convective currents and consequently locally enhanced plating and etching. The convective currents are created because of the sharp temperature gradient between the heated and unheated regions, i.e., between the regions which have absorbed the laser light and those which have not. This method has yielded enhancement factors of up to 10/3/ in plating and 10/4/ in etching, and possible the plating of spots and lines as small as 3 micrometers linear dimension. The limitation in size is believed to be in laser focus.

A method is described herein which has the advantages of the above described method for certain configurations and also has several additional advantageous properties. Illustratively, Fig. 1 shows an electrically insulating substrate 1 with a current-carrying line consisting of a thin "flash" of nichrome 2, with a thicker layer of gold 3. The gold layer 3 is discontinuous, and current flowing along the line is forced through the nichrome at the gold discontinuity 4. Because of the high resistance at this point, the nichrome will locally heat up by I/2/R heating. Placing the substrate in a gold electroplating solution 6 and biasing gold line 3 negatively with respect to the anode 5 causes an e...