Thin Glass Cloth Yarn Configuration for PCB Signal Skew Reduction
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Solution Overview
Problem
Conventional glass cloths used in printed wiring boards suffer from signal quality deterioration due to skew, uneven yarn widths, and gaps in the glass cloth, which hinder the reduction of delay time differences and productivity.
Innovation Solution
A glass cloth with a specific configuration of warp and weft yarns, where the glass filaments have diameters between 0.5 μm and 4.5 μm, and are bundled in specific numbers to achieve optimal weaving densities and fiber-opening efficiency coefficients, resulting in a thickness of less than 10.0 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the glass cloth thickness is reduced by using fewer glass filaments with smaller fiber diameter, then the thickness decreases, but gaps occur between filaments causing uneven yarn width and signal quality deterioration
Solution Approach 1:
The patent changes the parameters of glass filaments by specifying a diameter range of 0.5 μm to 4.5 μm and controlling the number of filaments between 150-3000 per yarn. This parameter optimization ensures sufficient filament density to prevent gaps while maintaining reduced thickness, thereby achieving both thin profile and uniform yarn width without the defects of conventional approaches
Solution Approach 2:
Instead of using an excessively small number of filaments that would create gaps, the patent employs a sufficient number of filaments (150-3000 per yarn) within the optimized diameter range. This partial action approach provides just enough filament density to ensure continuous coverage and uniform yarn width while still achieving the goal of reduced glass cloth thickness
2Manufacturing precision
If the weaving density is increased to reduce gaps and improve uniformity, then the yarn width uniformity improves, but the productivity decreases
Solution Approach 1:
The patent optimizes the weaving density parameter by controlling the number of filaments per yarn (150-3000) and filament diameter (0.5-4.5 μm), achieving a balance where sufficient uniformity is obtained without requiring excessive weaving density that would slow production. This parameter optimization allows standard weaving speeds to produce both uniform and continuous glass cloth
3Stability of the object's composition
If the fiber-opening treatment is strengthened to separate filaments, then the filament separation improves, but the yarn width unevenness increases due to gaps
Solution Approach 1:
The patent changes the fundamental parameters of the glass filaments by specifying a diameter range of 0.5 μm to 4.5 μm and controlling the number of filaments (150-3000 per yarn). These parameter changes ensure that even with fiber-opening treatment, the filaments remain densely enough packed to prevent gaps and maintain uniform yarn width, while still allowing adequate separation for proper resin impregnation
Data Source
AI summary
Provided is a glass cloth that can reduce a delay time difference of a printed wiring board and for which high productivity can be achieved. In the glass cloth, a glass filament diameter of the warp yarn and the weft yarn is from 0.5 to 4.5 μm, the filament number of each is from 150 to 3000, the weaving density of each is from 1.0 to 50.0 filaments/25 mm, the average yarn width of each is from 550 to 10000 μm, the fiber-opening efficiency coefficient of each is from 0.600 to 1.500, the ratio of the filament number to the filament diameter is from 68.6 to 555.5, the geometric mean of the opening efficiency coefficients of the warp yarn and the weft yarn is from 0.770 to 1.200, and the thickness of the glass cloth is less than 10.0 μm.