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BLISTER Elimination in RISTON T168

IP.com Disclosure Number: IPCOM000040516D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kuczynski, JP: AUTHOR [+3]

Abstract

Printed circuit panels that are manufactured using a method involving the additive plating of circuit lines on a prepreg surface occasionally experience blisters which become visible only after the electroless deposition of the copper-plated circuits. The blisters are seen as small round areas of resist poor adhesion along the plated copper lines and are related to functional defects, including copper spots and insulation/resistance failure. Following hot roll lamination of RISTON * T168 onto the seeded prepreg surface, micro-voids/micro-capillaries are formed between the resist and the prepreg. The minute channels function as a semi-permeable membrane between the bulk additive bath solution and the sandwiched Reten/seed mixture.

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BLISTER Elimination in RISTON T168

Printed circuit panels that are manufactured using a method involving the additive plating of circuit lines on a prepreg surface occasionally experience blisters which become visible only after the electroless deposition of the copper-plated circuits. The blisters are seen as small round areas of resist poor adhesion along the plated copper lines and are related to functional defects, including copper spots and insulation/resistance failure. Following hot roll lamination of RISTON * T168 onto the seeded prepreg surface, micro-voids/micro-capillaries are formed between the resist and the prepreg. The minute channels function as a semi-permeable membrane between the bulk additive bath solution and the sandwiched Reten/seed mixture. Water from the additive bath, driven by an imbalanced chemical potential, permeates through these capillaries, collecting in pockets. The stress induced by osmotic pressure is relieved by the lifting of resist in this area resulting in a blister.

Decreasing the chemical potential imbalance provides a simple solution to the blister problem; this is accomplished by increasing the molar concentration of solute in the additive bath using a substance which is inert with respect to the plating reaction. It has been demonstrated that the addition of sufficient sodium sulfate (a species which dissociates to produce spectator ions in the plating process) to the additive bath eliminates blisters. As predicted by ...