Wiring Substrate Corner Electrode Asymmetry for Solder Balance
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Solution Overview
Problem
Conventional wiring substrates face challenges in achieving optimal electrical connections between electronic components and module substrates due to uneven distribution and size of external electrodes, leading to inconsistent solder volumes and potential connection deviations.
Innovation Solution
The design features a square insulating substrate with first and second external electrodes, where the first electrodes are located at corners with smaller areas and larger widths orthogonal to the substrate sides, and the second electrodes are interposed between them, optimizing solder distribution and connection balance across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external electrodes are uniformly distributed on the insulating substrate, then manufacturing is simple, but solder volume becomes inconsistent and connection reliability deteriorates
Solution Approach 1:
The patent applies local quality by making different external electrodes have different areas and width ratios according to their specific positions. Corner electrodes (first external electrodes) have smaller areas and larger width ratios, while intermediate electrodes (second external electrodes) have larger areas and smaller width ratios. This localized differentiation optimizes solder distribution and connection reliability for each electrode type, resolving the contradiction between uniform simplicity and connection quality.
2Strength
If external electrode areas are increased to improve solder connection, then connection strength improves, but solder volume consistency deteriorates due to uneven distribution
Solution Approach 1:
The patent implements local quality by differentiating electrode areas based on position: corner electrodes have smaller areas while intermediate electrodes have larger areas. This localized area differentiation ensures that each electrode receives appropriate solder volume, improving both connection strength and solder volume consistency simultaneously.
Solution Approach 2:
The patent applies asymmetry by creating intentional asymmetry in electrode dimensions - specifically, the width ratio (width in direction orthogonal to substrate side / width parallel to substrate side) differs between corner electrodes and intermediate electrodes. This asymmetric design compensates for positional variations and achieves consistent solder distribution across all electrodes.
3Manufacturing precision
If external electrode width ratio is increased for better solder distribution, then solder volume consistency improves, but connection reliability deteriorates due to improper size balance
Solution Approach 1:
The patent applies local quality by optimizing the width ratio specifically for corner electrodes (first external electrodes) while maintaining appropriate areas. This localized parameter optimization ensures that corner electrodes achieve good solder distribution without compromising connection reliability, as each electrode type receives tailored dimensional specifications.
Data Source
AI summary
A wiring substrate includes an insulating substrate that is square in plan view, the insulating substrate having one main surface with a recess and an other main surface opposite to the one main surface, and external electrodes located on the other main surface of the insulating substrate and in a peripheral section of the insulating substrate. The external electrodes include first external electrodes and second external electrodes. In plan view, the first external electrodes are located at corners of the insulating substrate, and the second external electrodes are interposed between the first external electrodes. Each of the first external electrodes has a smaller area and a larger width in a direction orthogonal to each side of the insulating substrate than each of the second external electrodes.