Electroless Plating on LTCC Substrates via Silver Precipitation
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Solution Overview
Problem
The existing electroless plating methods for LTCC substrates face issues with glass floating, leading to non-plating and uneven plating coatings due to varying glass component sizes, resulting in recesses and voids that can cause solder connection failures and reduce module reliability.
Innovation Solution
An electroless plating method that includes a silver precipitation treatment step between degreasing and activation, allowing silver to be selectively deposited on glass components, followed by catalyzing and multi-layered electroless plating, ensuring even coating and preventing voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pretreatment agent containing a reducing agent is used to remove glass components, then non-plating is prevented, but large glass components (exceeding 1 μm) cannot be removed and recesses are generated in the wiring pattern surface
Solution Approach 1:
The patent changes the chemical parameters of the pretreatment agent by specifying pH ranges (pH 2-4 for first pretreatment, pH 4-6 for second pretreatment) and component concentrations to optimize glass component removal while preserving surface flatness. This resolves the contradiction by finding optimal parameter conditions that achieve both reliable plating and precise surface geometry.
Solution Approach 2:
The patent applies preliminary pretreatment steps before electroless plating to remove glass components and organic contaminants in advance. By performing surface preparation beforehand with controlled chemical treatments, the patent prevents non-plating issues while avoiding excessive surface etching that would create recesses.
2Reliability
If glass components are completely removed to prevent non-plating, then plating coating uniformity is improved, but voids are generated in the plating coating due to surface recesses
Solution Approach 1:
The patent controls the pH and composition parameters of pretreatment agents to achieve partial rather than complete glass component removal. This selective removal prevents non-plating while avoiding deep etching that would create void-forming recesses, thus eliminating both harmful effects through parameter optimization.
Solution Approach 2:
The patent applies partial removal action by using controlled pretreatment that removes sufficient glass components to prevent non-plating but stops before creating excessive surface depression. This partial action approach prevents both non-plating and void formation by finding the optimal removal threshold.
3Reliability
If multi-layered electroless plating is performed to ensure wire bonding property and solderability, then connection reliability is improved, but process complexity increases
Solution Approach 1:
The patent combines multiple plating layers (electroless nickel plating, electroless palladium plating, and electroless gold plating) into an integrated multi-layered coating system. By merging these functions into a coordinated process with unified pretreatment, the patent achieves comprehensive connection reliability while managing overall process complexity through systematic integration.
Solution Approach 2:
The patent creates a multi-layered plating coating that simultaneously provides wire bonding property, solderability, and corrosion resistance. Each layer performs multiple functions, reducing the need for separate treatment steps and thereby managing complexity while enhancing overall connection reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method prevents non-plating and voids in the nickel plating coating, enhancing module reliability by ensuring a uniform and adherent electroless plating on the LTCC substrate surfaces.
Implementation Method 1
a silver precipitation treatment step of precipitating silver on a glass component present on the surface of a wiring pattern formed of a silver sintered body
Implementation Method 2
a catalyzing step of providing a catalyst onto the surface of the wiring pattern formed of a silver sintered body
Data Source
AI summary
Provided is an electroless plating method for a low temperature co-fired glass ceramic substrate, the method including: a degreasing and activation treatment step of degreasing and activating a surface of a wiring pattern formed of a silver sintered body; a catalyzing step of providing a catalyst onto the surface of the wiring pattern formed of a silver sintered body; and an electroless multi-layered coating plating treatment step. The electroless plating method further includes, between the degreasing and activation treatment step and the catalyzing step, a silver precipitation treatment step of precipitating silver on a glass component present on the surface of the wiring pattern formed of a silver sintered body after the degreasing and activation treatment step, and the catalyzing step includes providing the catalyst also to the silver precipitated in the silver precipitation treatment step.