Semiconductor Device Solder Dam for Flow Restriction
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Solution Overview
Problem
Existing semiconductor device manufacturing methods face challenges with solder resist, including high costs, time-consuming screen printing processes, and impaired solderability due to outgassing and contamination, especially in hydrogen gas atmospheres, which limit the reliability and effectiveness of solder bonding.
Innovation Solution
A semiconductor device with a dam material made from an inorganic substance with high solder heat resistance, painted or thermally sprayed in a predetermined pattern on the metal base to restrict solder flow, eliminating the need for solder resist and preventing outgassing, thereby ensuring reliable soldering without contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder resist is used to prevent solder flow, then solder flow is restricted, but cost increases and production time increases due to screen printing and drying processes
Solution Approach 1:
The invention extracts and eliminates the solder resist layer entirely, replacing it with a mechanical dam structure formed by positioning the circuit board at a specific height above the metal base. This removes the need for screen printing and drying processes, reducing production time while maintaining solder flow prevention through the dam effect created by the height difference.
Solution Approach 2:
The invention changes the parameter from chemical resistance (solder resist material properties) to mechanical resistance (height-based dam effect). By controlling the distance between the circuit board and metal base to be 0.5mm or more, the solder flow is restricted mechanically rather than chemically, eliminating the need for organic solder resist materials and their associated processing steps.
2Reliability
If solder resist is used to prevent solder flow, then solder flow is restricted, but cost increases due to screen making and printing processes
Solution Approach 1:
The invention extracts and eliminates the solder resist layer and all associated screen printing equipment and processes. The cost of screen making, printing materials, and drying equipment is eliminated, replacing these with a simple mechanical positioning system that uses the natural dam effect of the height difference between the circuit board and metal base.
Solution Approach 2:
The invention replaces expensive, complex solder resist processing with a simple, inexpensive mechanical positioning approach. The positioning structure can be a simple fixture or jig that does not require costly screen printing equipment, making the manufacturing process more economical.
3Reliability
If organic solder resist is used, then solder flow is prevented, but outgassing occurs in hydrogen atmosphere causing impaired solderability and device contamination
Solution Approach 1:
The invention extracts and eliminates organic solder resist materials entirely, replacing them with a mechanical dam structure. This removes the source of outgassing problems that occur when organic materials are exposed to high-temperature soldering processes, particularly in hydrogen atmosphere fluxless soldering. The positioning structure uses only the physical height difference to prevent solder flow, with no organic materials to decompose or outgas.
Solution Approach 2:
The invention changes from chemical prevention (organic solder resist) to mechanical prevention (height-based dam). By setting the distance to 0.5mm or more, the solder flow is restricted by the mechanical barrier of the positioning structure rather than by organic chemical resistance, eliminating outgassing and contamination issues entirely.
Data Source
AI summary
A semiconductor device includes a solder dam for restricting the flow of solder during manufacturing. The device includes a semiconductor chip bonded to a first side of a circuit board, a metal base for dissipating heat produced by the semiconductor chip, the metal base being bonded to a second side of the circuit board, and a dam material disposed on the metal base in a predetermined pattern for restricting the flow of solder used in bonding a plurality of the circuit boards to the metal base. By employing the solder dam, solderability is not impaired, device contamination can be avoided, and a highly reliable semiconductor device can be produced.