Strain Gauge Array Circuit Insulating Strips
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Solution Overview
Problem
The matrix circuit design for strain gauge arrays faces issues with cross insulation between horizontal and longitudinal circuits, leading to printing accuracy problems and potential open circuits under tensile stress due to the need for bridging and gluing during the first layer printing.
Innovation Solution
A direct-ink-writing method is employed to print strain gauge array circuits using insulating strips, where a first insulating layer is formed, followed by parallel silver lines, then insulating strips perpendicular to the silver lines, and finally a second circuit layer with branches, all while ensuring the functional layer is printed without contacting the insulating strips and encapsulated with a third insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bridging and gluing is used at cross positions during first layer printing to ensure insulation, then insulation between horizontal and longitudinal circuits is improved, but printing accuracy deteriorates due to raised steps affecting second layer printing
Solution Approach 1:
The insulating strips are printed in advance on the first circuit layer before the second circuit layer is printed. This preliminary placement of insulating material prevents the need for subsequent gluing operations, eliminating raised steps and ensuring accurate printing positions for the second layer while maintaining effective insulation between horizontal and longitudinal circuits.
2Reliability
If bridging and gluing is used at cross positions to ensure insulation, then insulation between circuits is improved, but structural stability deteriorates due to open circuits under tensile stress
Solution Approach 1:
The insulating strips are integrated directly into the printing process and bonded to the first circuit layer through the same printing and curing mechanism. This merging of the insulating structure with the circuit layer creates a unified, stress-resistant structure that maintains both insulation properties and structural stability under tensile stress, eliminating the vulnerability of separately applied glue.
3Reliability
If local glue dispensing is used for insulation, then insulation is achieved, but positioning accuracy deteriorates due to positioning errors
Solution Approach 1:
The manual or semi-automatic glue dispensing process is replaced with a digital direct-ink-writing printing system. This substitution enables precise digital positioning of insulating strips according to pre-programmed coordinates, eliminating positioning errors associated with mechanical glue dispensing and ensuring accurate alignment with circuit features.
Data Source
AI summary
In a direct-ink-writing (DIW) method for printing a strain gauge array circuit, several insulating strips are printed on the upper layer of the first circuit layer after the first circuit layer has been printed and cured, and the second circuit layer is then printed at the insulating strips. The functional layer of a strain gauge is printed and covered thereon without contacting the insulating strips; the head and tail electrodes of the functional layer are respectively connected to two layers of circuit layers; and finally, a layer of insulating material is printed for encapsulation. DIW is used to complete the whole printing. A new insulating method is used in a cross part of two silver lines of a row-column compound circuit. The local glue dispensing is changed to printing the insulating strips in routing regions, and ensures the strain transmission efficiency from the strain gauge substrate to the functional layer.