Welded Flexible Circuit Board Contact for Low-Resistance Joining
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Solution Overview
Problem
Existing methods for connecting flexible circuit boards to substrates often result in high resistance connections and risk the conductive layer burning during welding, and lack mechanical stability.
Innovation Solution
A contact arrangement with a conductive connecting element that is welded to both the flexible circuit board and substrate, forming a low-resistance, solder-free connection that includes a heat-absorbing element to reinforce the conductive layer and provide mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the flexible circuit board is directly welded to the substrate, then a solder-free electrical connection can be formed, but the electrically conductive layer burns away during laser welding
Solution Approach 1:
A connecting element made of copper or copper alloy is introduced as an intermediary component between the flexible circuit board and the substrate. This connecting element absorbs excess heat during laser welding through its higher thermal mass, preventing the thin electrically conductive layer of the flexible circuit board from burning away while still enabling a solder-free welded connection to the substrate
2Adaptability or versatility
If the electrically conductive layer is made thinner for flexibility, then the flexible circuit board can be bent without breaking, but the conductive layer burns away during welding
Solution Approach 1:
The connecting element serves as a heat buffer that protects the thin electrically conductive layer during welding. By placing this thicker copper or copper alloy layer on the flexible circuit board before welding to the substrate, the heat is absorbed by the connecting element rather than the thin conductive layer, enabling both flexibility and welding reliability
Solution Approach 2:
The connecting element is placed on the flexible circuit board before the welding process to provide beforehand cushioning against heat damage. This pre-positioned protective layer ensures that during subsequent laser welding, the thin electrically conductive layer is already protected from excessive heat that would cause burning
3Strength
If a traditional solder connection is used, then mechanical stability is achieved, but high resistance and solder contamination occur
Solution Approach 1:
The traditional mechanical solder connection system is replaced with a direct welded connection system. The connecting element enables this substitution by providing a robust copper or copper alloy interface that can be directly welded to the substrate, eliminating the need for solder while achieving both low electrical resistance and mechanical stability through the welded joint
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 solution achieves a durable, low-resistance electrical connection that prevents the conductive layer from burning during welding and provides mechanical reinforcement, allowing the flexible circuit board to be bent without breaking.
Implementation Method 1
the connecting element can form both a heat store for excess process heat during welding
Implementation Method 2
The connecting element is welded to the electrically conductive layer of the flexible circuit board and to the substrate such that a welded connection extends from the connecting element through the electrically conductive layer
Implementation Method 3
the welded connection is a laser welded connection. Advantageously, a circuit carrier, in particular a ceramic circuit carrier, can thus be welded to the flexible circuit board from only one side
Implementation Method 4
the welded connection is, for example, a resistance spot welded connection. Advantageously, during resistance welding, additional welding material for forming an electrical contact bridge between the flexible circuit board and the substrate can thus be formed by means of the connecting element
Data Source
AI summary
A contact arrangement. The contact arrangement has at least one electrically conductive substrate, in particular a circuit carrier. The contact arrangement also has a flexible circuit board having at least one reversibly bendable, electrically insulating film and at least one or only one electrically conductive layer. The electrically conductive layer is electrically conductively connected to the substrate. The contact arrangement has an electrically conductive connecting element, which is arranged on the electrically conductive layer of the flexible circuit board so that the connecting element and the substrate enclose the flexible circuit board between them. The connecting element is welded to the electrically conductive layer of the flexible circuit board and to the substrate such that a welded connection extends from the connecting element through the electrically conductive layer of the flexible circuit board, in particular transversely to a flat extent of the flexible circuit board, into the substrate.