Soft-Touch Solder Pressure Collet for Damage-Free Die Reflow
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Solution Overview
Problem
Conventional pressure collets used in reflow soldering processes often damage the die due to their structural configuration and material hardness, leading to inadequate adhesion between the die and the heat spreader, resulting in electrical circuitry issues and voids.
Innovation Solution
A pressure collet with a plate and contact pads made from different materials, where the contact pads are arranged in a pattern complementary to the die's pattern, allowing uniform pressure application without direct contact between the plate and the die, preventing damage and ensuring secure adhesion during reflow processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pressure collet is used to apply pressure to the die, then the die is prevented from moving during reflow soldering, but the die surface is damaged and marred due to the collet's structural configuration and material hardness
Solution Approach 1:
The pressure collet is segmented into multiple discrete contact pads rather than a continuous rigid surface. Each contact pad is independently configured to apply pressure to specific locations on the die, distributing the force and preventing concentrated stress that causes surface damage while maintaining overall pressure application for adhesion.
Solution Approach 2:
Different regions of the pressure collet have different properties - the contact pads are made of softer material with specific hardness characteristics suited for pressing without damage, while the body structure maintains rigidity for force transmission. This local differentiation allows pressure application without die surface damage.
2Force
If a hard material is used for the pressure collet to apply sufficient pressure, then the die is secured during reflow, but the thin-film structures of the die are damaged
Solution Approach 1:
The material hardness parameter of the contact pads is specifically controlled to be softer than conventional collets, with a hardness range that provides sufficient pressure application capability while being gentle enough on thin-film structures. This parameter optimization resolves the contradiction between force application and damage prevention.
3Reliability
If the pressure collet directly contacts the die surface, then pressure is applied to prevent die movement, but bends are created in the die and preform causing voids and loose connections
Solution Approach 1:
The segmented contact pad structure applies pressure at multiple discrete points rather than a continuous surface, distributing mechanical stress and preventing the creation of bends in the die and preform. This segmentation maintains connection integrity without causing deformation that leads to voids and loose connections.
Data Source
AI summary
A pressure collet that operably engages with a die in which the pressure collet is configured to land on predetermined positions of the die without damaging said die, a perform, or a heat spreader during a reflow process. The pressure collet further comprises a plate that has a mounting surface and a plurality of contact pads that operably engages with the mounting surface of the plate. The plurality of contact pads is configured to apply pressure to predetermined positions of a die without the mounting surface of the plate contacting the die during a reflow process. The plate of the pressure collet is also formed of a first material and the plurality of contact pads are formed of a second material different than the first material.