PCB Solder Aggregation for Junction Reliability
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Solution Overview
Problem
The challenge is to enhance the junction reliability of solder connections between electronic components and printed circuit boards while maintaining a reduced size and improved performance, as existing solutions either increase package size or compromise on terminal count due to the need for reinforcement lands.
Innovation Solution
A printed circuit board design featuring electronic components with first lands on the bottom face and corresponding second lands on the mounting face, along with a solder aggregation member and thermosetting resin, where the solder aggregation member is positioned outside the second lands, and the thermosetting resin is applied to the component and board outside the lands, forming a strong and reliable connection without the need for large reinforcement lands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reinforcement lands with area three times or more the connection land are provided at four corners outside the connection lands, then junction reliability is improved, but package size increases
Solution Approach 1:
The invention extracts the reinforcement function from the traditional large reinforcement lands and relocates it to a concentrated mass of solder material positioned at the corner of the connection lands. This solder mass serves dual purposes: as electrical connection and as mechanical reinforcement, eliminating the need for separate large reinforcement land structures.
Solution Approach 2:
The invention merges the connection land and reinforcement land functions into a single integrated structure. The corner portion of the connection land itself serves as the reinforcement point, and solder material is concentrated at this corner to provide both electrical connection and mechanical strength, combining multiple functions into one element.
2Reliability
If reinforcement lands are provided at four corners inside the connection lands, then junction reliability is improved, but number of signal terminals decreases
Solution Approach 1:
The invention extracts the reinforcement function from the connection land area and relocates it to the corner portions where solder material is concentrated. This allows the connection lands to maintain their full area for signal terminals while the corner solder masses provide the necessary mechanical reinforcement.
Solution Approach 2:
The invention applies local quality by concentrating solder material specifically at the corner portions of the connection lands rather than uniformly across the entire connection land area. This localized reinforcement provides mechanical strength where needed most (at the corners subject to stress) while preserving the full area for electrical connections.
3Quantity of substance
If solder junction size is reduced to increase number of terminals, then performance is improved, but junction reliability deteriorates
Solution Approach 1:
The invention applies local quality by concentrating solder material specifically at the corner portions of the connection lands rather than uniformly across the entire connection land area. This localized reinforcement provides mechanical strength where needed most (at the corners subject to stress) while preserving the full area for electrical connections.
Solution Approach 2:
The concentrated solder material at the corner portions acts as a cushioning element that absorbs mechanical stress and thermal expansion forces before they can damage the solder joints. This pre-positioned reinforcement protects the smaller solder junctions from failure under stress.
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 improves junction reliability by reducing stress from thermal expansion and impact, allowing for smaller component sizes and increased performance without the need for additional reinforcement lands, while also reducing material costs and radiation noise.
Implementation Method 1
a thermosetting resin adhered to the bottom face of the electronic component outside the plurality of first lands and to the mounting face of the printed wiring board outside the plurality of second lands
Implementation Method 2
a plurality of pieces of first solder each of which joins each of the plurality of first lands to corresponding one of the plurality of second lands
Implementation Method 3
a solder aggregation member provided outside the plurality of second lands on the mounting face; second solder formed on the solder aggregation member
Data Source
AI summary
Provided is a printed circuit board including: an electronic component having a bottom face and a side face, in which first lands are provided on the bottom face; a printed wiring board having a mounting face, in which second lands corresponding to the first lands are provided on the mounting face, and in which the electronic component is mounted such that the bottom face faces the mounting face; a solder aggregation member provided outside the second lands on the mounting face; pieces of first solder each of which joins each of the first lands to corresponding one of the second lands; second solder formed on the solder aggregation member; and a thermosetting resin adhered to the bottom face of the electronic component outside the first lands and to the mounting face of the printed wiring board outside the second lands.