FPC Cable Shield Layer Segmentation for Soldering Heat Transfer
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Solution Overview
Problem
The existing methods for bonding a flexible printed circuit (FPC) cable to a substrate, particularly when a shield layer is involved, face issues with electromagnetic wave leakage due to inadequate heat transfer and solder connection, leading to electrical shorts and inefficiencies in signal shielding.
Innovation Solution
A cable connection structure where a thermosetting resin-based adhesive with densely scattered fine solder particles is used between the FPC cable and the substrate, and the shield layer is configured as a conductive mesh structure near the connection area to enhance heat transfer and prevent electromagnetic wave leakage, while the rest of the shield layer remains as a conductive flat plate to manage heat efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a shield layer is formed on the FPC cable and a hot bar is pressed to melt solder, then solder connection can be achieved, but the heat supplied from the hot bar escapes through the shield layer and solder connection cannot be ensured
Solution Approach 1:
The shield layer is segmented into two distinct regions: a first region with a mesh structure that allows heat penetration for effective soldering, and a second region with a plate structure that provides electromagnetic shielding. This segmentation resolves the contradiction by allowing heat to reach the solder while maintaining shielding functionality in other areas.
Solution Approach 2:
Different regions of the shield layer are given different structures and properties: the first region (mesh structure) has high thermal conductivity and electromagnetic wave permeability for heat transfer, while the second region (plate structure) has high electromagnetic wave blocking capability. This local differentiation allows each region to optimize its function, resolving the heat escape problem while maintaining shielding effectiveness.
2Reliability
If the shield layer is removed from the connection portion to enable solder connection, then solder bonding can be ensured, but electromagnetic waves leak from the connection portion
Solution Approach 1:
The shield layer is divided into functional segments where the first region (mesh structure) allows electromagnetic wave passage for effective soldering, while the second region (plate structure) provides electromagnetic wave blocking. This segmentation enables solder connection reliability while preventing electromagnetic wave leakage through the appropriate shielding region.
Solution Approach 2:
The shield layer exhibits spatially varying properties: the first region has mesh structure with high electromagnetic wave permeability for soldering access, while the second region has plate structure with high electromagnetic wave blocking capability. This local quality differentiation resolves the contradiction by allowing soldering where needed while blocking electromagnetic waves where shielding is required.
3Object-generated harmful factors
If a connector is disposed on the substrate for FPC cable connection, then electromagnetic waves can be shielded, but the device thickness increases
Solution Approach 1:
The shield layer is merged with the FPC cable itself, integrating the shielding function directly into the cable structure rather than requiring a separate connector on the substrate. This integration maintains electromagnetic wave shielding effectiveness while reducing device thickness by eliminating the need for additional connector components.
Solution Approach 2:
The FPC cable is given multiple functions: it serves both as the signal transmission medium and as the electromagnetic wave shield. The shield layer on the FPC cable performs both shielding and structural functions, eliminating the need for separate shielding components and reducing overall device thickness.
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
This configuration ensures reliable solder bonding and effective shielding of electromagnetic waves, preventing leaks and ensuring secure electrical connections while maintaining efficient heat transfer.
Implementation Method 1
when heat is applied to a connection agent in which fine solder particles are scattered in a thermosetting resin-based adhesive, the fine solder particles melt for solder bonding and the adhesive is cured for electrical and physical bonding
Implementation Method 2
the fine solder particles melt for solder bonding
Implementation Method 3
the adhesive is cured for electrical and physical bonding
Implementation Method 4
The shield layer has high thermal conductivity, and the heat supplied from the hot bar escapes through the shield layer
Implementation Method 5
each signal line can be shielded by the connector. Thus, electromagnetic waves leaking from the connection between the FPC cable and the substrate can be eliminated
Data Source
AI summary
A cable connection method is provided. In a cable connection structure, a connection agent in which fine solder particle are densely scattered in a thermosetting resin-based adhesive is interposed between a connection portion of a flexible printed cable (FPC) cable in which a shield layer is formed on one surface side of a signal layer and a connection portion on a substrate side. Then, the connection portion of the FPC cable and the connection portion on the substrate side are solder connected by heating. A shield layer corresponding to the connection portion of the FPC cable and/or a region portion up to a position separated from the base end side of the connection portion of the FPC cable by a predetermined length is configured with a conductive mesh structure body. The other region of the shield layer contains a conductive flat plate structure.