Thermoplastic Resin Semiconductor Case Terminal Bonding

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Solution Overview

Problem

Existing semiconductor devices face challenges in securely bonding metal terminals to resin cases due to gaps between protrusions, leading to insufficient securing force, which complicates the manufacturing process and reduces product yield, especially during wire bonding operations.

Innovation Solution

The method involves using induction heating to thermoplastically bond metal terminals to a thermoplastic resin case, ensuring secure attachment by forming solidified molten resin portions at interfaces, thereby eliminating the need for adhesives and reducing the risk of resin deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If metal terminals are inserted between protrusions on the resin case, then the terminal can be positioned, but gaps remain that prevent sufficient securing force

Engineering Contradiction:

Improveterminal positioning accuracyVSAvoidsecuring force

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent changes the physical state of the resin from solid to molten and back to solid through heating and cooling. By heating the resin case to melt the resin and then cooling it to solidify, the resin flows into gaps and bonds the metal terminal securely to the resin case, transforming the securing mechanism from mechanical interference to thermal bonding

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the phase transition of the resin between solid and liquid states. The resin is heated to melt (liquid phase) allowing it to flow and fill gaps around the metal terminal, then cooled to solidify (solid phase), creating a strong bond that secures the terminal firmly to the resin case

Inventive Principle:

Principle #36Phase transitions

2Strength

If adhesive is applied to fill gaps and secure the metal terminal, then securing force is improved, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:

Improvesecuring forceVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The resin case itself serves the dual function of providing structural support and securing the metal terminal through its own material properties. By heating the resin case, it automatically melts and flows to fill gaps and bond the terminal, then solidifies to secure it, eliminating the need for separate adhesive materials and application processes

Inventive Principle:

Principle #25Self-service

3Strength

If adhesive is used to secure the metal terminal, then bonding strength is improved, but adhesive may spread to wire bonding surfaces reducing product yield

Engineering Contradiction:

Improvebonding strengthVSAvoidproduct yield

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent uses the resin case itself as an intermediary medium between the metal terminal and the wire bonding surfaces. The resin acts as a barrier that contains the bonding action locally at the terminal-resin interface, preventing any bonding material from spreading to the wire bonding surfaces while still providing strong bonding through the melting and solidifying process

Inventive Principle:

Principle #24Intermediary (Mediator)

4Strength

If heated metal pieces are used to fuse the resin around the terminal, then bonding is achieved, but the securing force is insufficient and resin deformation may occur

Engineering Contradiction:

ImprovebondingVSAvoidsecuring force sufficiency

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

Instead of heating metal pieces to melt the resin externally, the patent inverts the approach by heating the resin case directly to melt it, then using the molten resin's own cooling and solidification process to create the bonding force. This reverse approach ensures complete resin flow and bonding while avoiding localized overheating that causes deformation

Inventive Principle:

Principle #13The other way round (Inversion)

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 provides a stronger bonding force of 30-40 N initially, increasing to 80-100 N, ensuring reliable wire bonding and reducing manufacturing complexity while avoiding adhesive-related defects and resin deformation.

Implementation Method 1

a heating device for heating the metal terminal by induction heating

Methodology Applied

Scientific EffectInduction heating: Induction Heating

Implementation Method 2

heating the mounted metal terminal by induction heating to a temperature higher than the melting point of the thermoplastic resin case so that the mounted metal terminal is thermoplastically bonded to the thermoplastic resin case

Methodology Applied

Scientific EffectThermoplastic bonding: Melting

Data Source

PatentUS8785252B2Resin sealed semiconductor device and manufacturing method therefor

Publication Date: 2014.07.22 MITSUBISHI ELECTRIC CORP

AI summary

A semiconductor device includes a thermoplastic resin case, a semiconductor chip mounted within the thermoplastic resin case, a metal terminal having a wire bonding surface and an opposing contact surface, and a wire connected between the wire bonding surface and the semiconductor chip. The contact surface of the metal terminal is thermoplastically bonded at an area to the inside of the thermoplastic resin case.