Flexible Circuit Board Perforations for LED Attachment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Attaching surface mount devices (SMDs) to flexible circuit boards is challenging due to adhesion issues with conductive epoxies, which can cause the silver trace on printed circuits to detach from the polyester substrate before curing, leading to failed joints.
Innovation Solution
A flexible laminated circuit board is fabricated using metallic conductors like copper, with perforations in the upper laminate sheet to expose portions of the conductors for attaching SMDs, such as LED packages, using solder or conductive epoxy to ensure secure attachment, and laminating these conductors between sheets to form a robust circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive epoxy is used to attach SMDs to flexible circuit boards, then attachment is achieved, but adhesion failures occur causing silver trace detachment from polyester substrate
Solution Approach 1:
The patent introduces a double-sided adhesive tape as an intermediary layer between the LED module and the flexible circuit board. This adhesive tape with release film prevents direct contact between conductive epoxy and the silver trace, eliminating the adhesion failure mechanism while maintaining secure attachment through the adhesive tape's bonding surfaces.
Solution Approach 2:
The patent extracts the problematic conductive epoxy attachment method and replaces it with an adhesive tape-based system. By removing the direct epoxy-to-silver-trace interface, the invention eliminates the root cause of adhesion failures while achieving reliable SMD attachment through alternative bonding mechanisms.
2Reliability
If SMDs are attached to flexible circuit boards using conventional methods, then circuit functionality is achieved, but mechanical stability is compromised due to stress on connections
Solution Approach 1:
The patent segments the attachment system into distinct functional layers: LED module, double-sided adhesive tape with release film, and flexible circuit board. This segmentation isolates the LED module from mechanical stresses, allowing the adhesive tape to absorb connection stresses while maintaining circuit functionality and improving overall mechanical stability.
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
The method provides a reliable and durable attachment of SMDs to the flexible circuit board, preventing adhesion failures and enabling the creation of flexible LED lighting circuits suitable for area lighting fixtures with improved mechanical stability and reduced stress on connections.
Implementation Method 1
A flexible laminated circuit board is fabricated using metallic conductors like copper, with perforations in the upper laminate sheet to expose portions of the conductors for attaching SMDs
Data Source
Figure 1~2a
Figure 2b~2c
Figure 3
AI summary
Techniques are disclosed for making a flexible laminated circuit board using a metal conductor onto which a SMD may be attached. Conductive metal strips may be laminated to form a flexible substrate and the metal strips may then be perforated for the placement of LED package leads. The LED packages may be attached to the conductive strips using solder or a conductive epoxy and the upper laminate layer may include perforations exposing portions of the metal strips for the attachment of the LED packages. Alternatively, strings of LED packages may be fabricated by attaching LED packages to conductive strips and these strings may be laminated between flexible sheets to form a laminated LED circuit. Plastic housings may aid in attaching the LED packages to the conductive strips. The plastic housings and/or the laminate sheets may be made of a reflective material.