Multi-Layer Circuit Board with Solder Stop Layer for Rework
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display technologies face challenges in maintaining the reliability and maintainability of circuit boards due to damage to pads during the removal of faulty electronic components, leading to low maintainability and yield rates.
Innovation Solution
The circuit board design includes a substrate with multiple conductive layers, insulating layers, and stop layers that form intermetallic compounds with solder, along with an anti-oxidation layer to prevent oxidation and simplify the soldering process, ensuring reliable connections and easy re-soldering of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If conventional circuit board design is used, then initial soldering can be performed, but pads are damaged during removal of faulty electronic components leading to low maintainability
Solution Approach 1:
The conductive layer is segmented into multiple functional layers: a first conductive layer for initial soldering, a stop layer for reaction control, and a second conductive layer for re-soldering. This segmentation allows the pad structure to withstand component removal and re-soldering cycles without damage.
Solution Approach 2:
The stop layer is pre-formed between the first and second conductive layers before any soldering operations. This preliminary action creates a controlled reaction barrier that prevents excessive intermetallic compound growth during subsequent soldering and re-soldering processes, protecting the pad integrity.
2Ease of repair
If multiple soldering operations are performed, then component re-soldering is enabled, but pad damage occurs reducing yield rates
Solution Approach 1:
The stop layer acts as a cushioning barrier between soldering operations. It controls and limits the growth of intermetallic compounds during each soldering cycle, preventing the cumulative damage that would otherwise occur during multiple soldering and re-soldering operations, thereby maintaining high yield rates.
Solution Approach 2:
The invention changes the chemical and structural parameters of the conductive layers by introducing the stop layer with specific material composition and thickness. This parameter change creates a controlled reaction environment that allows multiple soldering operations without degrading pad quality, ensuring high productivity.
3Ease of repair
If complex multi-layer conductive structure is used, then repeated soldering is enabled, but manufacturing complexity increases
Solution Approach 1:
The stop layer serves as an intermediary between the first and second conductive layers. It mediates the chemical reactions between solder and conductive layers, controlling intermetallic compound formation. This intermediary approach enables repeated soldering while keeping the overall structure manageable and manufacturable.
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 design enhances the maintainability and yield rates of the circuit board by allowing repeated soldering of electronic components without damaging the pads, improving the overall reliability and performance of the display apparatus.
Implementation Method 1
the main conductive layer is configured to be capable of creating a first intermetallic compound with solder
Implementation Method 2
the stop layer is configured to be capable of creating a second intermetallic compound with the solder
Implementation Method 3
A rate of a reaction between the stop layer and the solder is lower than a rate of a reaction between the main conductive layer and the solder
Implementation Method 4
the anti-oxidation layer is configured to be capable of creating a third intermetallic compound with the solder
Implementation Method 5
an anti-oxidation layer to prevent oxidation and simplify the soldering process
Data Source
AI summary
A circuit board includes a substrate, a first conductive layer, a first insulating layer and a second conductive layer. The first conductive layer includes a plurality of first conductive portions. The second conductive layer includes a plurality of second conductive portions. A second conductive portion passes through a first via hole in the first insulating layer to be in electrical contact with a first conductive portion. The first conductive layer and the second conductive layer each include at least one main conductive layer, which is capable of creating a first intermetallic compound with solder. At least one of the first conductive layer and the second conductive layer further includes a stop layer capable of creating a second intermetallic compound with the solder. A rate of a reaction between the stop layer and the solder is lower than a rate of a reaction between the main conductive layer and the solder.