Flexure Wall Portion Prevents Adhesive Overflow
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Solution Overview
Problem
In hard disk drives, the adhesive used to fix a piezoelectric actuator to a tongue portion can flow outside its intended range, affecting positioning accuracy and mechanical strength, and adhering to connecting terminals or outrigger portions, which compromises the reliability of the connection and spring properties.
Innovation Solution
A flexure design with a metal base, a circuit member, and a wall portion that prevents adhesive from adhering to protected areas, featuring a pad with a height difference from the metal base surface, and a reservoir region to contain the adhesive, ensuring it does not flow to protected regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied to fix the actuator to the tongue portion, then the actuator is firmly fixed, but the adhesive flows outside the pad to adhere to protected areas such as reference holes and connecting terminals
Solution Approach 1:
The tongue portion is divided into distinct functional zones: a pad area for actuator fixation and a protected area for reference holes and connecting terminals. The wall portion acts as a boundary separating these segments, preventing adhesive from crossing between them while maintaining strong fixation on the pad.
Solution Approach 2:
The wall portion serves as an intermediary structure between the pad and the protected areas. It physically blocks the adhesive from reaching the reference holes and connecting terminals while still allowing the adhesive to bond strongly to the pad, thus solving the contradiction between fixation strength and positioning accuracy.
2Strength
If adhesive is applied to cover the entirety of the pad, then sufficient mechanical strength is ensured, but the adhesive may overflow from the pad to adhere to the outrigger portion, affecting spring properties
Solution Approach 1:
The tongue portion is segmented into the pad area and the outrigger portion, separated by the wall portion. This segmentation allows the adhesive to cover the entire pad for maximum mechanical strength while the wall prevents the adhesive from overflowing to the outrigger portion, preserving the spring properties.
Solution Approach 2:
The wall portion acts as an intermediary barrier between the pad and the outrigger portion. It contains the adhesive within the pad boundary, ensuring sufficient mechanical strength from complete pad coverage while preventing adhesive overflow that would compromise the spring properties of the outrigger portion.
3Device complexity
If the pad is at the same height as the metal base surface, then the structure is simple, but the adhesive cannot be contained and will flow to protected regions
Solution Approach 1:
The wall portion extends in the vertical dimension (height direction) from the metal base surface, creating a three-dimensional containment structure. This vertical dimension allows the adhesive to be contained within the pad boundary while maintaining a relatively simple overall structure, preventing adhesive flow to protected regions and ensuring connection reliability.
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
Prevents adhesive overflow and ensures reliable adhesion of the actuator to the tongue portion, maintaining positioning accuracy and mechanical strength while preventing adhesive from reaching sensitive areas, thus enhancing the connection reliability and spring properties.
Implementation Method 1
an actuator using a piezoelectric element or the like tends to be mounted on a suspension
Implementation Method 2
The adhesive before it is applied and cured has liquidity. Accordingly, part of the adhesive may flow to the periphery from the applied portion
Data Source
AI summary
A flexure includes a metal base, a circuit member, and an actuator. The circuit member includes a base insulating layer, a conductor layer, and a cover insulating layer. The conductor layer includes a second pad, and a reference hole, which is an example of a portion to be protected, in a tongue portion. A second end portion of the actuator is fixed to the second pad via an adhesive. The circuit member includes a wall portion. The wall portion is formed between the second pad and the reference hole. A height of the wall portion is greater than a height of the second pad.