Disk Device FPC Wire Overlap to Prevent Chip Tilting
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Solution Overview
Problem
The uneven thickness of flexible printed circuit boards in disk devices due to non-overlapping pads causes an imbalance in solder surface tension, leading to chip inclination and potential short circuits during reflow, affecting design flexibility and stability.
Innovation Solution
The flexible printed circuit board design includes first and second conductive layers with specific wire configurations, such as wider parts overlapping pads and symmetric pad arrangements, to maintain uniform thickness and stabilize chip mounting, preventing tilting and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pads are arranged non-overlapping on the flexible printed circuit board, then design flexibility is improved, but the thickness becomes uneven causing chip inclination during reflow
Solution Approach 1:
The patent applies local quality by making the thickness of the flexible printed circuit board variable at different locations. Specifically, the board has a first thickness at pad locations and a second, greater thickness at wire locations. This local variation compensates for the non-overlapping pad arrangement, ensuring uniform overall thickness and preventing chip inclination during reflow while maintaining design flexibility.
2Adaptability or versatility
If the flexible printed circuit board has uneven thickness due to non-overlapping pads, then design flexibility is maintained, but chip inclination occurs during reflow
Solution Approach 1:
The patent makes the flexible printed circuit board have different thicknesses at different locations - greater thickness at wire locations and smaller thickness at pad locations. This local quality variation compensates for the non-overlapping pad arrangement, ensuring uniform overall thickness and preventing chip inclination during reflow while maintaining design flexibility.
3Adaptability or versatility
If pads are positioned further from chips to accommodate wire routing, then routing flexibility is improved, but surface tension imbalance causes chip tilting
Solution Approach 1:
The patent applies local quality by varying the thickness of the flexible printed circuit board at different locations. The board has greater thickness at wire locations and smaller thickness at pad locations. This compensates for pads being positioned further from chips, maintaining uniform overall thickness and preventing chip tilting during reflow, thus ensuring reliable chip mounting while preserving routing flexibility.
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 ensures stable chip mounting and reduces the likelihood of short circuits, enhancing design flexibility and maintaining signal integrity in disk devices.
Implementation Method 1
the solder between the pad and the chip relatively far from each other applies larger surface tension to pull the chip toward the flexible printed circuit board
Data Source
AI summary
A disk device according to one embodiment includes a magnetic disk, a magnetic head, an FPC, and a chip. The FPC includes an insulating layer, a first conductive layer on a first face of the insulating layer, and a second conductive layer on a second face of the insulating layer. The chip is mounted on the FPC. The first conductive layer includes pads. The chip includes terminals connected to the plurality of pads via solder. The second conductive layer includes wires. The plurality of wires include at least either one or two or more first wires or one or two or more pairs of second wires. The first wires each include a first part disposed apart from the pads, and a second part having a larger width than the first part, overlapping one of the pads. The second wires overlap one of the pads.