Multilayer Substrate Wiring Adjusting Impedance
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Solution Overview
Problem
Conventional multilayer substrates with laminated dielectrics and signal conductors face impedance differences due to varying connection distances, leading to uneven impedance in wiring portions, resulting in signal loss, especially at high frequencies.
Innovation Solution
The multilayer substrate design includes wiring adjusting portions with specific lengths and shapes to equalize impedance between signal conductors, using planar intermediate ground conductors for increased isolation and allowing for a winding shape of the wiring adjusting conductor to fit in narrow spaces without excessive conductor loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If signal conductors are disposed at different positions in the lamination direction, then the transmission line structure is more flexible and compact, but the interlayer-connection conductor lengths become different causing impedance variation
Solution Approach 1:
The patent applies local quality by adding wiring adjusting portions to specific interlayer-connection conductors that connect signal conductors at different positions. These adjusting portions are selectively added to conductors that are shorter than others, localizing the compensation action to where it is needed. This allows the structure to maintain flexibility with conductors at different positions while locally correcting the impedance inconsistency by extending specific conductor paths with additional wiring portions.
2Device complexity
If wiring portions have different lengths to connect signal conductors at different positions, then the connection structure is simplified, but the impedance of wiring portions becomes different causing signal loss
Solution Approach 1:
The patent applies parameter changes by modifying the length parameter of interlayer-connection conductors through the addition of wiring adjusting portions. Instead of changing the fundamental structure or material properties, the solution directly adjusts the length parameter of specific conductors to achieve impedance matching. This allows the connection structure to remain simple while correcting the impedance mismatch that causes signal loss by changing only the dimensional parameter of the affected conductors.
3Reliability
If impedance of wiring portions is made consistent, then signal transmission quality is improved, but additional wiring adjusting portions increase the conductor length and potential loss
Solution Approach 1:
The patent applies the blessing in disguise principle by converting the potentially harmful effect of extended conductor length into a beneficial outcome. The wiring adjusting portions do extend the conductor length, which could increase loss, but they simultaneously achieve impedance matching that prevents signal reflection and distortion. The net effect is improved signal transmission quality because the benefit of impedance consistency outweighs the minor increase in conductor length, effectively converting the apparent disadvantage into an acceptable compromise for achieving reliable high-frequency signal transmission.
Data Source
AI summary
A multilayer substrate includes a laminate, signal conductors, and external connection conductors. The signal conductors are at different positions in a lamination direction of the laminate. The external connection conductors are provided on a back surface of the laminate. A first signal conductor is connected at one end to one of the external connection conductors by a first wiring conductor. A second signal conductor is connected at one end to one of the external connection conductors by a second wiring conductor. The first signal conductor is closer to the back surface than the second signal conductor. The first wiring conductor includes wiring adjusting conductors each having a length corresponding to a distance difference in the lamination direction between the first and second signal conductors.