PCB Thermal Pad With Inserted Metal Coins for High Power RF Transistors
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Solution Overview
Problem
Current methods for fixing high power RF transistors to PCBs, such as the bolt down and surface mounted techniques, face issues with efficiency, consistency, stability, and cost, particularly in heat dissipation and mechanical reliability, especially for high power devices.
Innovation Solution
A thermal pad on the PCB with metal or alloy coins inserted into plated cutouts and bonded to the side walls, combined with plated through vias plugged with a solder mask, providing enhanced heat dissipation and RF ground connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the through-via technique is used to improve heat dissipation, then the ability to dissipate heat is improved, but the cost of the PCB increases significantly (about 30 percent)
Solution Approach 1:
The invention divides the heat dissipation function into two parts: through vias for thermal conduction and an attached coin for additional heat sinking and RF grounding. This segmentation allows optimization of each component's function while controlling overall cost.
Solution Approach 2:
The invention adds a dimensional element by attaching a coin (extending beyond the PCB surface) to provide enhanced heat dissipation and RF ground connections without requiring increased PCB thickness or complex internal via structures throughout the entire board.
2Temperature
If manual bolt down technique is used to fix high power transistor, then heat dissipation is improved, but working efficiency is low and consistency is poor
Solution Approach 1:
The attached coin structure provides self-aligning features that guide the high power transistor into proper position during mounting, reducing dependence on operator skill and manual adjustment while maintaining effective thermal and electrical connections.
3Ease of manufacture
If PCB thickness is reduced for cost-effectiveness, then manufacturing cost is reduced, but mechanical stability and heat dissipation may be compromised
Solution Approach 1:
The invention combines the PCB substrate with a metal coin attachment to create a composite thermal management structure. This composite approach provides enhanced mechanical stability and heat dissipation capabilities without requiring increased PCB thickness, maintaining cost-effectiveness while improving reliability.
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 offers improved thermal and RF ground performance, increased reliability, and cost-effectiveness by allowing for flexible design and reduced PCB thickness, while maintaining mechanical stability and efficient heat dissipation for high power RF transistors.
Implementation Method 1
bonded to side walls of the corresponding one of the or more plated cutouts with a paste capable of resisting a temperature of 250° C. or above
Implementation Method 2
providing enhanced heat dissipation and RF ground connections
Data Source
AI summary
A thermal pad (602, 612, 622, 702, 712) formed on a Printed Circuit Board and a method (900) of formed the thermal pad (602, 612, 622, 702, 712) are provided. The thermal pad (602, 612, 622, 702, 712) comprises in its interior one or more coins (604, 614, 624, 704, 714) has a height equal to a thickness of the PCB, and is made of metal or alloy, inserted into a corresponding one of one or more plated cutouts straight through the PCB in the thermal pad, and bonded to side walls of the corresponding one of the one or more plated cutouts with a paste capable of resisting a temperature of 250° C. or above. The plurality of through via (606, 616, 626, 706, 716) are plated, and lugged with a solder mask. The thermal pad (602, 612, 622, 702, 712) has a flat top surface and a flat bottom surface, either of which is coplanar with a corresponding one of top and bottom surfaces of the PCB. A PCB having formed thereon the above thermal pad (602, 612, 622, 702, 712) is also provided.