Laser Bonding Conductive Paste Stainless Steel HDD Suspension
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Solution Overview
Problem
The challenge is to stably achieve good conductive bonding between stainless steel and a conductive material in the low current range without increasing production processes or material costs, as the passivation film on stainless steel surfaces inhibits conductivity and is difficult to remove and maintain.
Innovation Solution
A method involving applying a conductive material in paste or liquid form to stainless steel, removing the passivation film using laser irradiation or a jig to prevent air contact, and ensuring contact between the conductive material and stainless steel without the passivation film, thereby maintaining a stable conductive state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the passivation film on stainless steel surface is removed by scratching or other methods, then conductivity between stainless steel and conductive material improves, but the passivation film restores quickly due to contact with air, making the bonding process unreliable
Solution Approach 1:
The patent applies inert atmosphere by filling the bonding chamber with inert gas (nitrogen or rare gas) to prevent oxygen contact with the stainless steel surface during the bonding process. This prevents passivation film restoration while allowing ohmic bonding to occur, solving the reliability issue without requiring complex mechanical film removal processes
2Reliability
If plating with nickel or gold is applied to stainless steel to increase conductivity, then conductive bonding improves, but the number of production processes and material costs substantially increase
Solution Approach 1:
The patent extracts and removes the passivation film from the stainless steel surface using laser irradiation or chemical etching, then bonds the conductive material directly to the exposed metal surface. This eliminates the need for additional plating processes (nickel or gold) while achieving stable ohmic bonding, thereby reducing both process complexity and material costs
3Weight of moving object
If the base plate and load beam are made thinner for lighter weight, then weight reduction is achieved, but the strength and difficulty of maintaining conductivity without plating increase
Solution Approach 1:
The patent replaces mechanical/plating-based conductivity solutions with laser irradiation or chemical etching methods that directly modify the stainless steel surface. This allows thin components to achieve stable ohmic bonding without requiring thick plating layers or complex mechanical film removal, maintaining both weight reduction and bonding 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 effectively bonds stainless steel and conductive materials in a reliable, ohmic conductive state, preventing passivation film restoration and ensuring stable conductivity in the low current range, suitable for HDD magnetic head suspensions.
Implementation Method 1
A method involving applying a conductive material in paste or liquid form to stainless steel, removing the passivation film using laser irradiation
Data Source
AI summary
A method of bonding a conductive material to stainless steel includes: a first step of applying a conductive paste to a surface of a base plate made of the stainless steel; and a second step of removing, in an area located within the surface of the base plate and covered with the conductive paste, a part of a passivation film on a surface of the stainless steel without allowing a base material of the stainless steel of the base plate to come into contact with air. The removing of the passivation film is achieved, for example, by irradiation of laser light.