Flexible Circuit Board Flatness Improvement for SMT Bonding
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Solution Overview
Problem
Surface mounter technology (SMT) fails to properly bond flexible circuit boards with printed circuit boards due to bending caused by the mounter or heat, resulting in reduced bonding flatness.
Innovation Solution
A flexible circuit board design featuring a signal line between two grounds, a dielectric layer, and a flatness improvement portion made of photo-imageable solder resist, preimpregnated material, or metal on the upper portion of the board, which includes a protrusion to improve flatness and prevent bending during mounting, and a tray with an inclined surface to facilitate accurate insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If surface mounter technology is used to bond flexible circuit board to printed circuit board, then automated mounting is achieved, but bonding flatness deteriorates due to bending caused by mounter or heat
Solution Approach 1:
The patent applies preliminary action by pre-forming a flatness improvement portion on the flexible circuit board before the mounting process. This protrusion is created in advance to counteract the bending that will occur during automated mounting, ensuring the board maintains proper flatness when bonded to the printed circuit board despite the automated mounter's heating and handling forces
2Reliability
If flexible circuit board is heated during mounting process, then solder bonding is achieved, but board bending increases reducing bonding quality
Solution Approach 1:
The patent applies preliminary anti-action by creating a flatness improvement portion that预先 opposes the bending effect caused by heat during soldering. The protrusion is designed to counteract the thermal expansion and bending forces that occur when the mounter heats the board for solder bonding, maintaining the board's flatness throughout the thermal process
3Productivity
If mounter adsorbs flexible circuit board for mounting, then automated placement is achieved, but board bending occurs reducing bonding flatness
Solution Approach 1:
The patent applies preliminary action by pre-forming the flatness improvement portion on the flexible circuit board before it enters the automated mounting process. This ensures that when the mounter adsorbs and handles the board for efficient automated placement, the pre-existing protrusion counteracts any bending forces applied during gripping and transport, maintaining bonding flatness throughout the high-speed mounting process
Data Source
AI summary
In one example, a flexible circuit board includes a signal line disposed between a first ground and a second ground; a dielectric disposed between the first ground and the signal line and between the second ground and the signal line; and a flatness improvement portion disposed on an upper portion of the second ground.