Copper Plating Process Using Bromide Pre-treatment for Uniform Thick Layers
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Solution Overview
Problem
Existing copper plating methods struggle to achieve uniformly deposited and mirror-finish copper layers thicker than 20 μm on flexible printed circuit boards, leading to surface roughness and poor physical characteristics.
Innovation Solution
Incorporating a pre-treatment solution with at least 0.75 mg/l of bromide compound ions into the copper plating process, which includes a degreasing and acid activation process, to enhance the uniformity and smoothness of the copper plating layer, using a copper plating solution with specific ratios of chloride and bromide ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional copper plating methods are used to deposit thick copper layers (greater than 20 μm), then the copper layer thickness requirement is met, but the surface becomes rough and uniformity is lost due to substrate roughness and grain size variations
Solution Approach 1:
The patent applies preliminary action by introducing a pre-treatment solution containing bromide compound ions before the copper plating process. This pre-treatment modifies the substrate surface to enable subsequent deposition of thick, uniform copper layers. The bromide ions prepare the surface in advance, allowing the copper plating to proceed with improved uniformity even at greater thicknesses.
Solution Approach 2:
The patent changes chemical parameters by adding bromide compound ions (at least 0.75 mg/l) to the pre-treatment solution. This parameter change fundamentally alters the surface properties and plating behavior, enabling the deposition of thick copper layers with maintained surface uniformity. The specific concentration of bromide ions is a critical parameter that enables the resolution of the contradiction between thickness and uniformity.
2Manufacturing precision
If chloride compound ions are added to copper plating solution to improve conductivity and plating quality, then plating uniformity improves, but bromide compound ions are needed in the pre-treatment solution to achieve thick uniform layers
Solution Approach 1:
The patent segments the plating process into distinct stages with different chemical compositions: a pre-treatment solution containing bromide compound ions followed by a copper plating solution containing chloride compound ions. This segmentation allows each solution to be optimized for its specific function, with bromide preparing the surface and chloride enabling uniform plating, thereby resolving the contradiction between plating quality and solution complexity.
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
The method allows for the deposition of copper layers with excellent external appearance and even surface finish, even at thicker thicknesses, improving the quality and luster of copper-plated membranes on flexible printed circuit boards.
Implementation Method 1
electrolytic plating is generally performed after a degreasing process for the removal of the oils and fats that are adhering to the surface of the printed circuit board
Implementation Method 2
copper plating is utilized for the wiring layers that are formed on the surfaces of circuit boards and for the conductive layers of the wall surfaces of the through holes
Data Source
AI summary
Providing a copper plating method with which to precipitate copper-plated membranes that are uniform and flat, and that have good mirror gloss even when relatively thin copper plated membranes are formed. A copper plating method wherein the object to be plated and a pre-treatment solution in which bromide compound ions are contained are brought into contact and copper is precipitated by means of electrical plating using a copper plating solution.