Reflective Circuit Board Layout to Reduce Substrate Warpage
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Solution Overview
Problem
The existing manufacturing processes for circuit boards face challenges with substrate warpage due to tensile stress from reflective layers, leading to unreliable connections and reduced product yield, especially when high-temperature processes are involved.
Innovation Solution
A circuit board design featuring a first reflective layer with mutually spaced reflective patterns and gaps, where pad zones are distributed within the outer contours of the patterns, and a second reflective layer with strategically placed hollows, both made with specific materials and adhesive layers to manage stress and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a continuous reflective layer is applied on the substrate, then the reflectivity is improved, but the substrate warpage increases due to tensile stress
Solution Approach 1:
The continuous reflective layer is divided into multiple spaced reflective patterns (first reflective patterns and second reflective patterns) with gaps between them. This segmentation reduces the tensile stress on the substrate while maintaining sufficient reflectivity, thereby reducing substrate warpage.
Solution Approach 2:
Different regions of the substrate are assigned different reflective properties through first and second reflective patterns with different reflectivities. The first reflective patterns have higher reflectivity than the second reflective patterns, creating local quality variations that optimize both reflectivity and stress distribution.
2Strength
If high-temperature processes are applied during manufacturing, then the adhesive strength is improved, but the substrate warpage increases due to thermal stress
Solution Approach 1:
The reflective layer is segmented into spaced patterns rather than continuous, which reduces the overall tensile stress on the substrate during high-temperature processes. This allows higher processing temperatures to achieve better adhesive strength without excessive warpage.
Solution Approach 2:
The processing temperature is increased to enhance adhesive strength, while the segmented reflective pattern structure compensates for the resulting warpage by reducing tensile stress. This parameter change in temperature is made possible by the structural modification.
3Illumination intensity
If the reflective layer is made with high reflectivity material, then the light output is improved, but the cost increases
Solution Approach 1:
Different reflective patterns are assigned different reflectivities based on local requirements. First reflective patterns with higher reflectivity are placed in regions requiring more light output, while second reflective patterns with lower reflectivity are used in other regions, optimizing light output while reducing material cost.
Solution Approach 2:
The reflective layer is segmented into multiple patterns rather than using a single continuous high-reflectivity layer, allowing selective application of high-reflectivity materials only where needed, thereby reducing overall material cost while maintaining sufficient light output.
Data Source
AI summary
The present disclosure provides a circuit board, an electronic apparatus and a manufacturing method for a circuit board. The circuit board includes: a substrate; a plurality of pad zones on the substrate; and a first reflective layer, where the first reflective layer is located at the same side of the substrate as the plurality of pad zones, the first reflective layer includes a plurality of mutually spaced reflective patterns, a gap is provided between the adjacent reflective patterns, and the first reflective layer has a first hollow in a zone where each pad zone of the plurality of pad zones is located.