Slit-Layer Circuit Board Layout for Reflow-Stable Semiconductor Modules
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Solution Overview
Problem
Conventional semiconductor modules face challenges in efficient heat dissipation and installability due to thermal deformation of the circuit board during the reflow process, leading to potential cracking of the fixing agent and reduced non-defective product rates.
Innovation Solution
The semiconductor module incorporates a circuit board design with strategically placed upper and lower surface slits in the circuit and metal layers, which deform concavely towards the semiconductor chips post-reflow, increasing the thickness of the solder and reducing warpage, thereby enhancing heat dissipation and installability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the circuit board is made rigid to maintain structural stability, then the board strength is improved, but thermal deformation during reflow causes solder cracking and reduces manufacturing yield
Solution Approach 1:
The circuit board is segmented by introducing slits that divide the rigid structure into flexible sections. These slits allow the board to deform locally during thermal cycling without transmitting stress to the solder joints, thus maintaining both structural integrity and solder reliability.
Solution Approach 2:
The circuit board's mechanical parameters are changed by adding slits that modify its flexibility and thermal deformation characteristics. The slits enable the board to undergo controlled deformation during reflow soldering, preventing stress concentration that would otherwise cause solder cracking.
2Reliability
If the circuit board is made flexible to accommodate thermal deformation, then solder cracking is reduced, but the board warpage increases and heat dissipation efficiency decreases
Solution Approach 1:
The slits segment the circuit board structure, creating controlled flexibility zones that accommodate thermal expansion without causing overall board warpage. This segmentation allows local deformation while maintaining global planarity.
Solution Approach 2:
The slits convert the harmful thermal deformation into a beneficial controlled flexibility. Instead of resisting thermal expansion (which causes stress and cracking), the slits allow controlled deformation that protects the solder joints while maintaining board shape stability.
3Stability of the object's composition
If the circuit board thickness is increased to reduce warpage, then board stability is improved, but heat dissipation efficiency decreases due to increased thermal resistance
Solution Approach 1:
Rather than increasing overall board thickness, the invention uses slits to create a segmented structure that provides stability through controlled flexibility. This maintains thin board design for optimal heat dissipation while preventing warpage through the slit-induced deformation control.
4Ease of manufacture
If conventional circuit board design is used without slits, then manufacturing process is simple, but thermal deformation causes solder cracking and reduces non-defective product rate
Solution Approach 1:
The slit pattern is integrated into the circuit board manufacturing process using standard PCB fabrication techniques. The segmentation is achieved through simple etching or routing operations that add minimal complexity to the manufacturing process while dramatically improving yield by preventing solder cracking.
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 effectively suppresses cracking of the solder and improves the installability of the semiconductor apparatus while maintaining efficient heat dissipation without reducing the non-defective product rate.
Implementation Method 1
thermal deformation of the circuit board during the reflow process
Implementation Method 2
efficient heat dissipation
Data Source
AI summary
A semiconductor apparatus includes first and second semiconductor chips, and a circuit board. The circuit board is a laminated board sequentially including an insulating plate, a circuit layer, and a metal layer. The circuit layer includes a first mounting portion on which the first semiconductor chip is installed, a second mounting portion on which the second semiconductor chip is installed, and a first and second upper surface slit provided between the first and second mounting portion and extending in a first direction. The metal layer includes a first lower surface slit extending in the first direction. In a plan view, the first mounting portion, the first upper surface slit, the second upper surface slit, and the second mounting portion are provided side by side in the second direction. The first lower surface slit is located within a range defined by the first and second upper surface slit.