Low Expansion Support for Printed Wiring Board Curing
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Solution Overview
Problem
The existing methods for manufacturing printed wiring boards using the buildup method face issues with the expansion of supports during thermal curing, leading to impaired flatness of the insulating layer and reduced yield due to resin composition being pushed by the support, resulting in wrinkles, lifting, and resin chip adhesion.
Innovation Solution
The use of a support with predetermined expansion properties, specifically satisfying certain expansion coefficient conditions in the machine direction (MD) and transverse direction (TD) when heated, to prevent excessive expansion and ensure the resin composition layer remains flat during thermal curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a support is used during thermal curing of resin composition layer, then the resin composition can be contained and cured properly, but the support expands during heating causing the resin to be pushed and form raised parts that exceed support thickness
Solution Approach 1:
The patent changes the physical parameters of the support by controlling its thermal expansion coefficient and glass transition temperature. The support is designed to have a thermal expansion coefficient of 0.01-0.06%/°C and a glass transition temperature of 80-120°C, which prevents excessive expansion during curing and eliminates raised parts formation.
Solution Approach 2:
The patent directly addresses the thermal expansion issue by selecting support materials with specific expansion characteristics. The support's thermal expansion coefficient is controlled to match or be slightly less than the resin composition's expansion coefficient, preventing the support from pushing the resin and forming raised parts during the curing process.
2Manufacturing precision
If the resin composition is thermally cured with support attached, then the insulating layer is formed, but wrinkles and lifting of support occur lowering the yield
Solution Approach 1:
The patent modifies the support's physical parameters, specifically setting the glass transition temperature between 80-120°C. This parameter change ensures the support maintains appropriate flexibility during curing, preventing wrinkles and lifting that would otherwise reduce manufacturing yield.
Solution Approach 2:
The support is constructed as a composite material combining polyester resin with specific additives and fillers. This composite structure provides the desired balance of thermal expansion properties, mechanical strength, and flexibility to prevent surface defects during the curing process.
3Ease of manufacture
If the support is peeled off after curing, then the insulating layer is released, but raised parts are dropped out and adhere to the insulating layer causing resin chip adhesion
Solution Approach 1:
By controlling the support's thermal expansion coefficient to be 0.01-0.06%/°C and glass transition temperature to be 80-120°C, the patent ensures that no raised parts form during curing. Consequently, when the support is removed, there are no raised parts to detach and adhere to the insulating layer, eliminating resin chip adhesion issues.
4Productivity
If conventional supports are used in buildup method, then the process can be completed, but the flatness is impaired and yield is reduced due to support expansion
Solution Approach 1:
The patent achieves both high productivity and manufacturing precision by optimizing the support's physical parameters. The thermal expansion coefficient (0.01-0.06%/°C) and glass transition temperature (80-120°C) are specifically controlled to prevent raised parts formation, ensuring flat insulating layers while maintaining efficient manufacturing processes.
Solution Approach 2:
The patent resolves the contradiction between productivity and precision by controlling the support's thermal expansion behavior. The support's expansion coefficient is matched to or slightly less than the resin's expansion coefficient, preventing differential expansion that would cause surface defects, thereby maintaining both high yield and manufacturing efficiency.
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 effectively reduces the formation of raised parts and improves the uniformity and thickness of the insulating layer, enhancing the yield of printed wiring boards by maintaining the flatness and preventing resin chip adhesion.
Implementation Method 1
the support expands in the thermal curing step
Data Source
AI summary
A method for manufacturing a printed wiring board which includes: Step (A) of laminating an adhesive sheet including a support and a resin composition layer bonded to the support to an inner layer board so that the resin composition layer is bonded to the inner layer board; Step (B) of thermally curing the resin composition layer to form an insulating layer; and Step (C) of removing the support, in this order, in which the support satisfies a condition (MD1): a maximum expansion coefficient EMD in an MD direction at 120° C. or more is less than 0.2% and a condition (TD1): a maximum expansion coefficient ETD in a TD direction at 120° C. or more is less than 0.2% below, when being heated under predetermined heating conditions, does not lower the yield even when the insulating layer is formed by thermally curing the resin composition layer with a support attached to the resin composition layer.