Heat Radiating Plate Warpage Control via Leveler and Cold-Rolling
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Solution Overview
Problem
Heat radiating plates for electronic part mounting substrates experience significant warpage variations due to plastic deformations during production, leading to unstable residual stress and insufficient warpage correction when made from materials with high thermal conductivity.
Innovation Solution
A method involving finish cold-rolling of annealed copper or copper alloys, followed by shaping correction using a leveler and progressive press-working, allowing the strip to bend under its own weight, to produce a heat radiating plate with minimal warpage variation and enhanced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the heat radiating plate is produced by press-forming by means of a progressive die with plastic deformations during correction of shape, then the opposite warpage can be achieved, but the variation in residual stress causes unstable warpage control
Solution Approach 1:
The strip is subjected to preliminary plastic deformation through a leveler before progressive die press-forming to pre-establish the desired opposite warpage. This preliminary action prepares the material in an optimal state for subsequent forming operations, ensuring stable and repeatable warpage control by reducing residual stress variations during intermittent feeding.
2Reliability
If the heat radiating plate is made from soft material with high thermal conductivity (Hv ≤ 135), then good thermal performance is achieved, but plastic deformations cause significant warpage variation
Solution Approach 1:
The material parameters are optimized by selecting copper or copper alloys with specific hardness ranges (Hv ≤ 135) that balance thermal conductivity and deformability. The processing parameters are also controlled, including the leveler deformation amount and progressive die pressing conditions, to achieve stable opposite warpage while maintaining high thermal conductivity of not less than 250 W/m·K.
3Ease of manufacture
If intermittent feeding is used in progressive die press-forming, then progressive shaping is achieved, but residual stress variation makes stable warpage control difficult
Solution Approach 1:
The leveler performs preliminary continuous deformation before the intermittent progressive die feeding, pre-establishing the opposite warpage and reducing residual stress variations. This separation of continuous preliminary deformation and intermittent final forming allows stable warpage control while maintaining the advantages of progressive press-forming for complex shaping.
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 results in a heat radiating plate with reduced warpage variation and improved thermal conductivity, ensuring stable bonding to electronic part mounting substrates while maintaining sufficient strength and thermal performance.
Implementation Method 1
the corrected strip is allowed to bend due to its own weight between the leveler and the feeder so that the minimum value of deflection (L1−L0) is 0.5 to 2.0 m
Implementation Method 2
finish cold-rolling an annealed material so that a ratio of the Vickers hardness HV after the finish cold-rolling to the Vickers hardness HV before the finish cold-rolling is not less than 1.2
Data Source
AI summary
A method for producing a heat radiating plate, the method containing the steps of: finish cold-rolling an annealed material to obtain a strip; causing the strip to wind in the shape of a coil to prepare a coil stock; unwinding the coil stock by means of an uncoiler to obtain a strip; causing the strip to pass through a gap between the rolls of a leveler to correct the shape thereof; progressively feeding the corrected strip to a progressive die via a feeder to progressively press-working the strip to produce a heat radiating plate.