Double-Sided Flexible Circuit Board Layout for Thermal Bonding Flatness
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Solution Overview
Problem
Conventional double-sided flexible circuit boards experience bonding failures due to poor flatness caused by height deviations in conductive lines of different widths, leading to uneven force application during thermal bonding.
Innovation Solution
The layout structure of a double-sided flexible circuit board is designed with inner supporting segments on the inner supporting region, where the width difference between segments is controlled to be less than 8 μm, ensuring similar heights and improved flatness for the thermal bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If supporting segments of different widths are designed to have the same height, then good flatness is displayed for the chip, but in practice wider conductive lines have higher height deviation than narrower conductive lines
Solution Approach 1:
The patent applies local quality by differentiating the design requirements for inner supporting segments versus outer supporting segments. Inner supporting segments under the chip mounting region are designed with width difference less than 8 μm to ensure high flatness for thermal bonding, while outer supporting segments can have larger width variations. This localized differentiation resolves the contradiction by applying strict height control only where it is critical for bonding quality.
Solution Approach 2:
The patent changes the width parameter of inner supporting segments to be within 8 μm of each other, which directly controls the height parameter through manufacturing processes. By setting a specific parameter range for segment widths, the patent ensures that height deviation remains within acceptable limits, thus resolving the contradiction between desired flatness and actual manufacturing precision.
2Adaptability or versatility
If supporting segments have different widths for different purposes, then functional requirements are met, but the thermal bonding head applies different forces causing bonding failure
Solution Approach 1:
The patent applies local quality by differentiating the design requirements for inner supporting segments versus outer supporting segments. Inner supporting segments under the chip mounting region are designed with width difference less than 8 μm to ensure high flatness for thermal bonding, while outer supporting segments can have larger width variations. This localized differentiation resolves the contradiction by applying strict height control only where it is critical for bonding quality.
Solution Approach 2:
The patent segments the supporting regions into inner supporting segments and outer supporting segments with different design criteria. This segmentation allows the inner segments to maintain uniform height for reliable bonding while outer segments can vary in width for different functional purposes, thus resolving the contradiction between functional versatility and bonding reliability.
3Area of stationary object
If wider supporting segments are used, then more support area is provided, but height deviation increases reducing flatness
Solution Approach 1:
The patent changes the width parameter of inner supporting segments to be within 8 μm of each other, which directly controls the height parameter through manufacturing processes. By setting a specific parameter range for segment widths, the patent ensures that height deviation remains within acceptable limits, thus resolving the contradiction between desired flatness and actual manufacturing precision.
Data Source
AI summary
A layout structure of double-sided flexible circuit board includes a flexible substrate having a first surface and a second surface, a first circuit layer and a second circuit layer. An inner bonding region is defined on the first surface and an inner supporting region is defined on the second surface according to the inner bonding region. The first circuit layer is located on the first surface and includes first conductive lines which each includes an inner lead located on the inner bonding region. The second circuit layer is located on the second surface and includes second conductive lines which each includes an inner supporting segment located on the inner supporting region. A width difference between any two of the inner supporting segment of the second conductive lines is less than 8 μm.