Semiconductor Chip Provisional Fixing for Void-Free Soldering
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Solution Overview
Problem
Existing power module manufacturing methods face challenges in preventing positional displacement of semiconductor chips and void formation during soldering, which can lead to reduced heat radiation and reliability issues.
Innovation Solution
A method involving dispersed provisional fixing portions on both the substrate and semiconductor chip, allowing for a single reflow process to bond the substrate, chip, and conductive member, while minimizing voids by using thermosetting pasty members that volatilize at a temperature lower than the solder's melting point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adhesive is applied to the entirety of the overlapping location to provisionally fix the semiconductor chip, then positional displacement is suppressed, but gas escape paths are blocked and voids form in the soldering portion
Solution Approach 1:
The adhesive application area is segmented from the entire overlapping location to only the peripheral region, creating gas escape paths in the center while maintaining positional fixation at the edges. This segmentation resolves the contradiction by allowing both positional accuracy and heat radiation performance to be achieved simultaneously.
Solution Approach 2:
Different regions of the overlapping location are assigned different functions: the peripheral region uses adhesive for positional fixation, while the central region remains adhesive-free to allow gas escape during soldering. This local differentiation resolves the contradiction by optimizing each region for its specific purpose.
2Ease of manufacture
If bonding is performed in one process without provisional fixing, then the process is simplified, but positional displacement of the semiconductor chip occurs
Solution Approach 1:
The semiconductor chip is provisionally fixed with adhesive before the soldering process, establishing its position in advance. This preliminary action prevents positional displacement during the subsequent single reflow process, resolving the contradiction between process simplicity and positional accuracy.
3Manufacturing precision
If pasty solder is used in wide area to provisionally fix the semiconductor chip, then positional displacement is suppressed, but voids easily form and heat radiation is reduced
Solution Approach 1:
The patent uses a temporary adhesive material for provisional fixation that is later removed or vaporized during the soldering process. This disposable provisional fixing method provides positional accuracy during assembly but does not interfere with final heat radiation performance, resolving the contradiction between positional fixation and heat radiation.
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 approach ensures high positional accuracy and reduces void formation, enhancing heat radiation and reliability by allowing a single reflow process and using silver-containing provisional fixing portions to reinforce solder joints.
Implementation Method 1
using thermosetting pasty members that volatilize at a temperature lower than the solder's melting point
Implementation Method 2
bonding the substrate, chip, and conductive member through a single reflow process
Data Source
AI summary
In a method for manufacturing a semiconductor device, a plurality of first provisional fixing portions are supplied on a front surface of a substrate such that the plurality of first provisional fixing portions are spaced from each other and thus dispersed. A first solder layer processed into a plate to be a first soldering portion is disposed in contact with the plurality of first provisional fixing portions. A semiconductor chip is disposed on the first solder layer. In addition a conductive member in the form of a flat plate is disposed thereon via a second provisional fixing portion and a second solder layer. A reflow process is performed to solder the substrate, the semiconductor chip and the conductive member together.