Asymmetric Land Configuration for Solder Alignment Precision
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Solution Overview
Problem
Existing electronic circuit substrates face challenges in preventing position deviation of surface mount components during soldering due to the uneven distribution of solder resist and the resulting force on heat dissipating leads, which can lead to alignment issues and manufacturing defects.
Innovation Solution
The electronic circuit substrate design features a printed wiring board with first and second lands arranged in one direction, where the first land has a larger bond area and a projected section for solder fillet inspection, and the second land has a smaller bond area, ensuring precise alignment by matching the outer side edges of the bond portions with the lands, thereby preventing excessive solder spread and position deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the second pad is covered with resist to prevent solder spread, then position deviation of surface mount component is reduced, but manufacturing complexity increases due to additional resist application steps and alignment requirements
Solution Approach 1:
The invention extracts the resist material from the second pad area, creating a resist-free zone that allows solder to naturally contain itself through capillary action boundaries defined by the pad geometry and solder paste application, eliminating the need for resist application and alignment steps
Solution Approach 2:
The invention segments the pad structure into a main section and an auxiliary section, where the auxiliary section acts as a solder containment barrier that prevents excessive solder spread without requiring resist material, thus simplifying the manufacturing process while maintaining positioning precision
2Manufacturing precision
If alignment lead terminals are extended longer than electrode lead terminals, then self-alignment effect is achieved, but component space requirements increase
Solution Approach 1:
The invention applies asymmetry to the land configuration rather than lead terminal lengths, with the first land having a larger bond area and the second land having a smaller bond area, creating an asymmetric solder distribution pattern that provides self-alignment without requiring extended alignment leads
Solution Approach 2:
Instead of extending lead terminals to achieve alignment (conventional approach), the invention inverts the approach by designing asymmetric lands that create self-alignment through solder flow patterns, eliminating the need for extended alignment leads and reducing component space requirements
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 configuration ensures high precision in preventing position deviation and reduces manufacturing defects, eliminating the need for excess space around the electronic component, thereby enhancing the reliability of the electronic circuit substrate.
Implementation Method 1
The electronic component has a first bond portion which is bonded to the first land with solder, and a second bond portion which is bonded to the second land with solder
Implementation Method 2
the surface mount component from being strongly pulled toward the heat dissipating lead side due to a force of the solder wettability
Data Source
AI summary
Provided is an electronic circuit substrate in which any excess space is not necessary around an electronic component, and position deviation at a time of mounting the electronic component can be prevented with high precision. An electronic circuit substrate 100 includes a printed wiring board 10 and an electronic component 20. The printed wiring board 10 has a first land 11 and a second land 12. The electronic component 20 has a first bond portion 24 which is bonded to the first land 11 with solder, and a second bond portion 25 which is bonded to the second land 12 with solder. The bond area of the first land 11 and the first bond portion 24 is larger than the bond area of the second land 12 and the second bond portion 25. In one direction D1, the position of an outer side edge 24b of the first bond portion 24 is set so as to match the position of the outer side edge 11b of the first land 11.