Method for producing printing circuit board

A printed circuit board and circuit technology, applied in the direction of printed circuit manufacturing, printed circuit, electrical components, etc.

Inactive Publication Date: 2003-11-05
SHIPLEY CO INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patented technology allows for effective removal of unwanted metallic deposits from certain areas without requiring any other process like chemical etching.

Problems solved by technology

This technical issue addressed in this patents relates to improving printing circuit board quality while maintaining good performance characteristics like signal transmission speed and resistance to corrosion. Specifically, these issues involve controlling the number of openings needed for proper connections between different layers within the board's interior space. Additionally, certain processes involving immersion lithography lead to nonuniform depositions due to residual materials left behind inside the via holes. These challenges make achieving effective control over all aspects related to the final appearance of the print circuit board product.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0067] Embodiment 1 (comparative example)

[0068] Bare copper laminated wiring board substrates with through holes not to be plated are subjected to the existing sequential steps of cleaning, through hole conditioning, and microetching prior to electroless nickel plating. The cleaning step is accomplished by contacting the substrate with a commercially available cleaning agent. After cleaning, the vias of the substrate were contacted with a commercially available alkaline via conditioner containing sodium thiosulfate. After via conditioning, the substrate was contacted with microetch A or B. Microetch A contained 100 g / L sodium persulfate and 2% sulfuric acid in water. Microetch B contained 100 g / L of potassium peroxomonosulfate and 2% aqueous sulfuric acid. Next, a nickel layer was electrolessly deposited on the substrate using a commercially available electroless nickel bath. After nickel deposition, the substrate was evaluated for nickel plating in through-holes that ...

Embodiment 2

[0071] Embodiment 2 (comparative example)

[0072] Using another bare copper laminated wiring board substrate having vias not to be plated, the procedure of Example 1 was repeated except that the via conditioning step was omitted. Therefore, the substrate was first cleaned using a commercially available cleaning agent, and then the substrate was contacted with Microetch A. After microetching, the substrate was contacted with the electroless nickel plating bath of Example 1. After evaluation, it was found that the vias that did not require plating had been electrolessly plated with nickel.

[0073] Therefore, it has been found that existing processes that omit the via conditioning step (ie, the process involves cleaning followed by direct microetching) do not prevent nickel deposition in vias that do not require plating.

Embodiment 3

[0075] Bare copper laminated wiring board substrates having through holes not to be plated are subjected to the sequential steps of pretreatment of the present invention, i.e., microetching, cleaning, and optionally a second micro-etch, prior to electroless nickel plating. etch. The microetching baths used for the experiments are reported in Table 2.

[0076] micro etching

[0077] The substrate is sequentially contacted with the microetch bath, removed from the microetch bath and rinsed using a commercially available cleaning agent, and contacted with a second microetch bath. A thiourea-free through-hole conditioning step was performed. Next, a nickel layer was electrolessly deposited from Example 1 on the substrate using a commercially available electroless nickel plating bath. After nickel deposition, the substrate was evaluated for nickel plating in through-holes that did not need to be plated. In addition, the impact of the process on the appearance of the su...

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PUM

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Abstract

The present invention provides a method and composition for manufacturing printed circuit boards, which can reduce or eliminate the problem of electroless nickel depositing in through holes that do not need to be plated. The present invention also provides a method and composition for maintaining smooth and bright finish deposits. The invention is particularly useful in the manufacture of printed circuit boards containing one or more electroless nickel immersion gold layers.

Description

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Claims

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Application Information

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Owner SHIPLEY CO INC
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