Ceramic Copper Circuit Board Structure for Thermal Stress Relief
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Solution Overview
Problem
Ceramic copper circuit boards face challenges in achieving high thermal resistance and power density due to limitations in thermal cycle test (TCT) characteristics and semiconductor element mounting, particularly with increasing operating temperatures and power module performance.
Innovation Solution
A ceramic copper circuit board design featuring a ceramic substrate with copper parts bonded via a brazing material, incorporating sloped portions and jutting portions to manage thermal stress, while maintaining sufficient surface area for semiconductor element mounting, using specific material compositions and manufacturing processes to enhance bonding strength and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the copper part thickness is increased to improve bonding strength and thermal conductivity, then the thermal stress relaxation and power density are improved, but the mounting surface area for semiconductor elements is reduced
Solution Approach 1:
The copper part side surface is divided into multiple functional regions: a sloped portion for stress relaxation, a flat portion for semiconductor mounting, and a jutting portion for additional stress management. This segmentation allows each region to perform its specific function optimally while maintaining overall bonding strength and sufficient mounting area.
Solution Approach 2:
The invention transitions from a simple planar copper surface to a three-dimensional structured surface with slopes and jutting portions. By utilizing the vertical dimension and creating angular features (sloped portions at 30-60 degrees), the design achieves stress relaxation without sacrificing horizontal mounting surface area.
2Reliability
If sloped portions are added to relax thermal stress, then TCT characteristics are improved, but the manufacturing complexity increases
Solution Approach 1:
The invention specifies precise parameter ranges for the sloped portions (30-60 degree angles, specific width ratios) to optimize stress relaxation while maintaining manufacturability. By defining clear parameter boundaries, the design achieves reliable TCT characteristics without excessive manufacturing complexity.
3Loss of energy
If the copper part thickness is increased to improve heat dissipation, then thermal conductivity is improved, but the overall module volume increases
Solution Approach 1:
The invention uses a thin copper part (0.3-1.0 mm thickness) with engineered surface features instead of a thick copper block. The sloped and jutting portions create effective stress relaxation and heat dissipation pathways without requiring increased material thickness, thus maintaining compact module volume while improving thermal performance.
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 design effectively relaxes thermal stress, improves TCT characteristics, and increases power density by controlling the width, length, and contact angles of sloped and jutting portions, ensuring durability and efficient heat dissipation even at high temperatures.
Implementation Method 1
A ceramic copper circuit board includes a ceramic substrate and a copper part. The copper part is bonded to the ceramic substrate via a brazing material
Implementation Method 2
The side surface of the copper part includes a sloped portion and a jutting portion. The jutting portion extends from an end portion of the sloped portion in a direction toward the ceramic substrate. By controlling the geometry of these features, thermal stress is effectively managed
Data Source
AI summary
A ceramic copper circuit board according to an embodiment includes a ceramic substrate and a first copper part. The first copper part is bonded at a first surface of the ceramic substrate via a first brazing material part. The thickness of the first copper part is 0.6 mm or more. The side surface of the first copper part includes a first sloped portion. The width of the first sloped portion is not more than 0.5 times the thickness of the first copper part. The first brazing material part includes a first jutting portion jutting from the end portion of the first sloped portion. The length of the first jutting portion is not less than 0 μm and not more than 200 μm. The contact angle between the first jutting portion and the first sloped portion is 65° or less.