Semiconductor Package Thermal Conduction Sheet with Concavo-Convex Metal Case
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Solution Overview
Problem
Existing heat radiating structures for semiconductor devices apply excessive mechanical stress to semiconductor packages and printed circuit boards due to inadequate stress relaxation, leading to potential damage and reduced service life.
Innovation Solution
A semiconductor device with a thermal conduction sheet having an elasticity that relaxes stress over time, featuring a metal case with concave and convex portions of different depths to distribute pressure and create an air gap, allowing for effective stress reduction and improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal conduction sheet with elasticity is used to fill the gap between the semiconductor package and metal case, then thermal conduction is improved, but excessive mechanical stress is applied to the semiconductor package and printed circuit board during assembly and over time
Solution Approach 1:
The metal case is designed with concave and convex portions at specific locations to create localized air gaps between the thermal conduction sheet and the metal case inner wall. This local modification allows stress relaxation at critical points while maintaining overall thermal conduction performance. The convex portions protrude toward the thermal conduction sheet to prevent complete contact, creating controlled stress relief zones.
Solution Approach 2:
The elastic thermal conduction sheet is selected and designed beforehand to have appropriate elasticity that allows it to be compressed during assembly to fill gaps and ensure thermal contact, while its elastic recovery provides ongoing stress relaxation. This pre-designed elastic property cushions the semiconductor package from excessive mechanical stress during the assembly process and throughout the device's operational life.
2Reliability
If the thermal conduction sheet is pressed firmly against the metal case to ensure thermal contact, then heat radiating performance is improved, but the semiconductor package and printed circuit board are damaged due to excessive stress
Solution Approach 1:
By introducing concave and convex portions at specific locations on the metal case inner wall, the design creates localized regions where the thermal conduction sheet does not fully contact the metal case. This local modification maintains adequate thermal contact in most areas while providing stress relief at critical points, preventing damage to the semiconductor package and printed circuit board.
Solution Approach 2:
The elastic thermal conduction sheet serves as an intermediary between the semiconductor package and the metal case. Its elasticity allows it to transmit thermal energy effectively while absorbing and distributing mechanical stress. The convex portions of the metal case act as additional intermediaries that prevent excessive compression, allowing the thermal conduction sheet to maintain thermal contact without transmitting damaging forces to the semiconductor package.
3Temperature
If a rigid structure is used to ensure stable heat radiation, then thermal performance is maintained, but stress cannot be relaxed over time leading to device failure
Solution Approach 1:
The metal case structure is modified by changing the physical parameters of its inner wall - introducing concave and convex portions that alter the contact geometry between the metal case and thermal conduction sheet. This parameter change creates a structure that maintains stable heat radiation through the thermal conduction sheet while allowing stress relaxation over time, thereby extending the device's service life.
Solution Approach 2:
The heat radiation system employs a composite structure combining the metal case (rigid, thermally conductive), the elastic thermal conduction sheet (flexible, thermally conductive), and the air gaps created by convex portions (stress-relieving, thermally insulating). This composite arrangement maintains stable heat radiation performance while incorporating stress relaxation mechanisms to prevent long-term failure.
4Stress or pressure
If the thermal conduction sheet is made thinner to reduce stress, then mechanical stress is reduced, but thermal conduction performance deteriorates
Solution Approach 1:
Instead of uniformly thinning the thermal conduction sheet, the design introduces localized air gaps through convex portions at specific locations on the metal case inner wall. This allows the thermal conduction sheet to maintain its original thickness and thermal conduction performance in most areas, while providing stress relief at critical points where the convex portions prevent complete contact with the metal case.
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 concavo-convex structure effectively reduces mechanical stress on semiconductor packages and printed circuit boards, enhancing reliability and thermal conductivity while preventing air sealing and electromagnetic interference.
Implementation Method 1
a thermal conduction sheet (3) arranged between the semiconductor package (2) and the metal case (5), coming into contact with the semiconductor package (2) and the metal case (5), and radiating a heat generated from the semiconductor package (2)
Implementation Method 2
the thermal conduction sheet (3) has an elasticity by which a stress is relaxed with time with respect to a pressure
Data Source
AI summary
The invention provides a heat radiating structure which reduces a mechanical stress applied to an electronic part mounted on a printed circuit board including a semiconductor package. The heat radiating structure is constructed by a semiconductor package mounted on a printed circuit board, a thermal conduction sheet arranged on an upper surface of the semiconductor package, and a metal case provided with a heat radiating fin for receiving a heat transmitted form the thermal conduction sheet so as to discharge to an atmospheric air, and the metal case is provided with a concavo-convex structure in a contact portion with the thermal conduction sheet.