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Electroplating of Printed Circuits and Microcontacts

IP.com Disclosure Number: IPCOM000091705D
Original Publication Date: 1968-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Le Mehaute, C: AUTHOR [+2]

Abstract

In the metal deposition process for the manufacturing of printed circuits, tin, lead or gold is replaced by a tin-nickel alloy. The substrate to be plated is covered by a photoresist, for example, KPL* and KPR*, in proportion of 1:3.5. After exposure with the desired pattern, the development is carried out with trichloroethylenr. Then drying is effected in an oven at 120 degrees C for one hour.

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Electroplating of Printed Circuits and Microcontacts

In the metal deposition process for the manufacturing of printed circuits, tin, lead or gold is replaced by a tin-nickel alloy. The substrate to be plated is covered by a photoresist, for example, KPL* and KPR*, in proportion of 1:3.5. After exposure with the desired pattern, the development is carried out with trichloroethylenr. Then drying is effected in an oven at 120 degrees C for one hour.

Then the tin-nickel electroplating is performed with the following bath: Sn Cl(2), 2H(2)O 20-50 g/1 Ni Cl(2), 6H(2)O 200-300 g/1 NH(4)F, HF 40 g/1 NH(4)OH (35 %) 35 cm pH = 2.5.

In order to obtain a well-adherent deposit and to avoid cracking during operations which follow the etching, the coating must have internal compression stresses. Consequently, either temperature is increased or current density is increased. These stresses must be controlled and parameters must be accurately adjusted. To have a compression stress of 5kg/mm/2/, the parameters are a temperature equal to 70 degrees C/+0/(-2) with a current density = 20 mA/cm/2/.

It is possible to cause stresses to vary within 15kg/mm/2/ in compression and 15 kg/mm/2/ in tension by acting upon temperature, current density, or by ammonium chloride addition. Further, the bath can be damaged by the presence, even infinitesimal, of some elements, such as copper, gold, and organic elements. *Trademarks of Eastman Kodak Co.

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