Heatsink-Integrated Insulating Circuit Board for Thick Copper Patterning
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Solution Overview
Problem
The increasing current through semiconductor elements leads to higher heat generation, requiring thicker circuit layers for improved conductivity and thermal conductivity, but this results in sagging and potential deterioration of insulating properties, especially when forming circuit patterns by etching, which also affects plating, soldering, and wire bonding processes.
Innovation Solution
A heatsink-integrated insulating circuit board with a circuit layer made of metal pieces arranged in a pattern on an insulating resin layer, where the angle between the metal piece and the resin layer is between 70° and 110°, and the surface roughness is controlled to ensure bonding reliability and prevent sagging, with specific root-mean-square height ratios between bonding and non-bonding surfaces to facilitate plating, soldering, and wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circuit layer is thickened to improve thermal conductivity and electrical conductivity, then the conductivity is improved, but sagging occurs on the end surface and insulating property deteriorates
Solution Approach 1:
The invention changes the geometric parameters of the circuit layer by controlling the end surface angle θ to be 45° or more (preferably 60° to 80°). This parameter control prevents sagging while maintaining thickness for good conductivity, thereby resolving the contradiction between improving conductivity and maintaining insulating property.
2Reliability
If the circuit layer is thickened to improve thermal conductivity, then the thermal conductivity is improved, but sagging occurs on the end surface
Solution Approach 1:
The invention controls the end surface angle θ of the circuit layer to be 45° or more, which prevents sagging on the end surface while allowing the circuit layer to maintain sufficient thickness for good thermal conductivity. This parameter control resolves the contradiction between improving thermal conductivity and maintaining end surface flatness.
3Ease of manufacture
If etching is performed to form circuit pattern, then the circuit pattern is formed, but sagging occurs and insulating property deteriorates
Solution Approach 1:
The invention controls the end surface angle θ to be 45° or more, which prevents sagging that would otherwise occur during etching processes. This parameter control allows circuit patterns to be formed while maintaining insulating property, resolving the contradiction between ease of manufacture and manufacturing precision.
4Reliability
If surface roughness is increased to improve bonding reliability, then bonding reliability is improved, but plating and soldering become difficult
Solution Approach 1:
The invention applies different surface roughness characteristics to different regions: the bonding surface has increased roughness (Sq1 > Sq2) for improved bonding reliability, while other surfaces maintain appropriate smoothness for plating and soldering. This local differentiation resolves the contradiction between bonding reliability and ease of manufacture.
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 provides excellent bonding reliability and insulating properties, enabling stable and cost-effective manufacturing of heatsink-integrated insulating circuit boards that support plating, soldering, and wire bonding while maintaining low production costs.
Implementation Method 1
a heat sink including a radiating fin
Implementation Method 2
a heat sink including a radiating fin
Implementation Method 3
an insulating resin layer formed on a top plate part of the heat sink
Data Source
AI summary
A heatsink-integrated insulating circuit board includes a heat sink including a radiating fin, an insulating resin layer formed on a top plate part of the heat sink, and a circuit layer arranged on one surface of the insulating resin layer. An angle θ formed between an end of the metal piece and a surface of the insulating resin layer is set to be 70° or more and 110° or less. Root-mean-square heights Sq1 and Rq1 in bonding surfaces to the insulating resin layer in the top plate part of the heat sink and the metal piece, and root-mean-square heights Sq2 and Rq1 in regions other than the bonding surfaces to the insulating resin layer in the top plate part of the heat sink and the metal piece have a relationship of Sq1>Sq2 or Rq1>Rq2.