PCB Heat Pipe Embedding Prevents Lamination Deformation
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Solution Overview
Problem
Conventional methods for embedding heat pipes in printed circuit boards (PCBs) face challenges due to deformation under high temperatures and pressures during lamination and reflow, which disrupt heat transport and can cause damage to the heat pipes.
Innovation Solution
A method involving the use of a heat pipe tube with an open end, where the tube is embedded between two substrates with the open end exposed, allowing it to be filled with a cooling medium and sealed after reflow, thus avoiding pressure build-up and deformation during manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional heat pipe is embedded in a PCB during lamination, then heat dissipation is improved, but the heat pipe may be deformed by internal pressure due to elevated temperature or by ambient pressure
Solution Approach 1:
The heat pipe is pre-filled with working fluid and sealed before the lamination process. This preliminary action ensures the heat pipe is already prepared and sealed, preventing any pressure build-up or deformation during the high-temperature lamination process that would otherwise occur if the heat pipe were sealed after embedding.
Solution Approach 2:
The manufacturing process is segmented into distinct stages: first embedding the pre-filled and sealed heat pipe, then performing lamination, and finally making electrical connections. This segmentation allows the heat pipe to be prepared under controlled conditions before exposure to the harsh lamination environment, preventing deformation while maintaining heat dissipation functionality.
2Reliability
If a heat pipe is embedded in a PCB during lamination, then heat transport is improved, but the heat pipe may be deformed by ambient pressure during lamination
Solution Approach 1:
The heat pipe is pre-filled with working fluid and sealed before the lamination process. This preliminary sealing action protects the heat pipe interior from ambient pressure during lamination, preventing deformation while maintaining heat transport efficiency through the pre-configured working fluid.
Solution Approach 2:
The heat pipe is designed with a robust sealed structure that cushions against ambient pressure during lamination. The pre-sealing creates a protective barrier that absorbs and distributes the ambient pressure, preventing deformation of the heat pipe while maintaining its heat transport functionality.
3Reliability
If reflow is performed to solder components to the PCB, then electrical connections are improved, but pressure builds up in the heat pipe which is detrimental
Solution Approach 1:
The heat pipe is pre-filled and sealed before the reflow process. This preliminary sealing prevents solder flux and molten solder from entering the heat pipe, and prevents pressure build-up during reflow that would otherwise occur in an open or post-reflow sealed heat pipe, while still allowing electrical connections to be made to the PCB.
Solution Approach 2:
The manufacturing process is segmented so that heat pipe sealing occurs before the reflow process. This segmentation isolates the heat pipe from the high-temperature, high-pressure reflow environment, preventing pressure build-up while allowing subsequent electrical connections to be made without affecting the sealed heat pipe.
4Reliability
If a heat pipe is sealed after embedding in the PCB, then heat transport is maintained, but the sealing process may cause deformation under high temperature and pressure
Solution Approach 1:
The heat pipe is pre-filled with working fluid and sealed before embedding in the PCB. This preliminary sealing action is performed under controlled conditions that prevent deformation, and the sealed heat pipe is then embedded and subjected to lamination and reflow processes without further sealing, thereby maintaining heat transport continuity while avoiding deformation during sealing.
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 approach prevents deformation and ensures efficient heat transport by maintaining the heat pipe's integrity during high-temperature and high-pressure processes, enabling effective heat dissipation in PCBs.
Implementation Method 1
The heat pipe comprises an envelope, a wick, and a working fluid and provides a cooling action by means of vaporization of the working fluid in the wick structure
Implementation Method 2
Heat transport will occur along the heat pipe from a hot part towards a cool part
Implementation Method 3
Conventional methods to form a PCB often involve high temperature and pressures above 2-3 MPa, during lamination of the PCB
Implementation Method 4
during the step of reflow, for soldering components to the PCB, the solder alloy is liquified and this often requires a temperature above 240° C.
Data Source
AI summary
The present invention relates to a method (100) of producing a printed circuit board (300), wherein the printed circuit board (300) comprises a first substrate (301), a second substrate (302), and a heat pipe tube (303) with an open end (304). The method comprises the step of forming (S100) a recess (305) in the first substrate (301), placing (S120) the heat pipe tube (303) in the recess (305) of the first substrate (301) such that the open end (304) is exposed, and laminating (S130) the first substrate (301) and the second substrate (302) with the heat pipe tube (304) embedded in the recess (305) between the first substrate (301) and the second substrate (302). The present invention also relates to a printed circuit board, a circuit board as well as a method for producing a circuit board.