Reworkable Passive Element Embedded PCB Design
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Solution Overview
Problem
Conventional semiconductor modules with passive elements mounted on the surface are prone to damage during handling, increasing the size and fabrication costs due to the non-reworkable nature of passive element embedded PCBs.
Innovation Solution
A reworkable passive element embedded PCB design featuring through holes with reflowable conductive fillings and insertion grooves allows for the embedding of passive elements, enabling reflow and reworkability, reducing the PCB height and eliminating the need for additional PCBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive elements are mounted on the surface of the PCB, then the PCB structure is simple and easy to manufacture, but the PCB height increases and the passive elements are exposed to damage during handling
Solution Approach 1:
The passive element is nested within the PCB structure by embedding it into a cavity formed in the PCB board. The conductive filling material is inserted into through-holes and then reflowed to embed the passive element securely within the PCB, achieving a compact integrated structure that reduces overall height while protecting the passive element from external damage.
2Length of stationary object
If passive elements are embedded in the PCB, then the PCB height is reduced and integration is improved, but the PCB becomes non-reworkable and requires additional PCBs increasing fabrication costs
Solution Approach 1:
The conductive filling material is selected to have a melting point suitable for reflow processing. By controlling the thermal parameters and using reflowable conductive material, the embedded passive element can be detached and reattached, enabling reworkability while maintaining the embedded structure's space-saving benefits.
Solution Approach 2:
The connection between the passive element and PCB is made dynamic rather than permanent. The reflowable conductive filling allows the passive element to be detached and reattached multiple times, providing flexibility for repair and replacement without requiring additional PCBs, thereby reducing fabrication costs.
3Stability of the object's composition
If passive elements are embedded in the PCB using conventional methods, then integration is improved, but the passive element cannot be detached for repair or replacement
Solution Approach 1:
The conductive filling material undergoes phase change during reflow processing. By heating above the melting point, the material transitions from solid to liquid state, allowing the passive element to be detached. Upon cooling, it solidifies again, maintaining secure electrical connection. This reversible phase change enables both stable integration and ease of repair.
Solution Approach 2:
The reflow process can be periodically applied to the embedded passive element. By heating the PCB to the melting point of the conductive filling material, the passive element can be detached for repair or replacement, then reattached by allowing the material to solidify. This periodic thermal action enables maintenance while preserving the embedded structure.
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
The solution reduces PCB height, enhances reworkability, and improves reliability by embedding passive elements, preventing electrical shorts and reducing fabrication costs.
Implementation Method 1
first and second fillings which are buried in the first and second through holes, respectively, and are formed of a reflowable conductive material
Data Source
AI summary
A reworkable passive element embedded printed circuit board (PCB) including a board member, first and second fillings, and a first passive element. The board member has first and second through holes which are spaced apart from each other. The first and second fillings are buried in the first and second through holes, respectively, and formed of a reflowable conductive material. The first passive element includes first and second electrodes. A first insertion groove is formed in a portion of a surface of the board member between the first and second through holes and portions of the first and second fillings. The first passive element is mounted on the first insertion groove. The first electrode includes a bottom surface and a side contacting the first filling and an exposed upper surface. The second electrode comprises a bottom surface and a side contacting the second filling and an exposed upper surface.