Polyimide Laminate Preheating for PCB Transmission Loss Reduction
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Solution Overview
Problem
Existing methods for manufacturing multilayer printed wiring boards with polyimide insulating layers fail to adequately reduce transmission loss, which increases over time due to water content in the insulating layers.
Innovation Solution
A method involving the use of first and second laminates, each containing a conductor layer and a polyimide insulating layer, which are heated under specific conditions to reduce water content, followed by stacking with a third insulating layer to form a multilayer printed wiring board with improved RF characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyimide insulating layers are used in multilayer printed wiring boards, then good electrical insulation and mechanical flexibility are achieved, but transmission loss increases over time due to water content absorption
Solution Approach 1:
The patent applies preliminary action by pre-heating the polyimide insulating layers to high temperatures (80-150°C) for extended periods (0.5-24 hours) before final assembly. This pre-treatment removes water content in advance, preventing subsequent water absorption that would cause transmission loss increases over time.
Solution Approach 2:
The patent changes the thermal parameters of the polyimide insulating layers by controlling heating temperature (80-150°C) and heating duration (0.5-24 hours). By adjusting these parameters, the water content in the polyimide is reduced to specific ranges (1-30 wt%), thereby stabilizing transmission loss characteristics.
2Reliability
If conventional manufacturing methods are used without pre-heating, then production efficiency is maintained, but transmission loss characteristics deteriorate over time
Solution Approach 1:
The patent performs preliminary heating of polyimide layers before final lamination and assembly. This pre-treatment step removes water content in advance, ensuring stable RF characteristics over time without requiring additional corrective steps later in the manufacturing process.
Solution Approach 2:
The patent combines the pre-heating step with existing manufacturing processes such as lamination or molding operations. By integrating the water removal treatment into the standard manufacturing flow, the patent minimizes additional cycle time while achieving reliable transmission loss characteristics.
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 method effectively reduces the transmission loss of the multilayer printed wiring board by minimizing water content in the polyimide insulating layers, thereby maintaining improved RF characteristics over time.
Implementation Method 1
a heating step including heating each of the first laminate and the second laminate under a condition including a heating temperature equal to or higher than 100° C. and a heating duration equal to or longer than half an hour
Data Source
AI summary
A method includes providing a first laminate and a second laminate. The first laminate includes a first conductor layer, a first insulating layer containing polyimide, and a second conductor layer. The second laminate includes a second insulating layer containing polyimide and a third conductor layer. The method further includes: heating each of the first laminate and the second laminate under a condition including a heating temperature equal to or higher than 100° C. and a heating duration equal to or longer than half an hour; and stacking, after the heating, the first laminate and the second laminate one on top of the other with a third insulating layer interposed between the second conductor layer and the second insulating layer.