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Reducing Low Frequency Arrival TMR With Flex Cable/J-block Glue Bead Disclosure Number: IPCOM000127368D
Publication Date: 2005-Aug-25
Document File: 6 page(s) / 941K

Publishing Venue

The Prior Art Database


A disk drive flex cable/J-block system using qualified glue/adhesive material to secure the boundary condition is disclosed. The proposed method is a cost and dynamic effective manner to reduce the induced flex cable on read/write head seeking position error TMR and to increase seek performance in higher track densities HDD storage devices.

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Page 1 of 6

Reducing Low Frequency Arrival TMR With Flex Cable /J-block Glue Bead


In order to achieve fast read/write time as well as high performance for customer's needs, it is well known and prudent that servo seek control loop needs to engage low frequency excitation to HDD actuator voice coil. Due to desired flexible nature, major flex cable natural modes in state of art HDD drives can range in frequency of 200-2000Hz, in which strong servo excitation is preserved to achieve the designed seek time. In this article, a low-cost mechanical mean securing flex cable/J-block boundary condition is proposed. Significant reduction of low-frequency seek arrival TMR is observed in its amplitude by using this invention and demonstrated on several prototypical small form factor drives. Practical effectiveness of the invention is strongly suggested and makes it an attractive proposition for future flex cable/J-block designs.

Advantage of Proposed Method The main idea of this article is to disclose and propose a method to enhance and secure boundary condition of flex cable at J-block location in a commercial HDD by applying qualified glue/adhesive material forming as a bead between them during flex cable and HSA assembling process. The advantages of using the proposed method are:

Low-frequency component of file level arrival TMR is greatly reduced in amplitude.



Consistency of flex cable/J-block boundary condition among files can be easily


achieved to maintain desirable settle TMR and performance.

Easy to manufacture in HDD assembly line and fairly low cost (almost nothing)

comparing to adding extra component like clip to secure flex/J-block boundary condition.


For a state-of-art HDD, a "real world" boundary condition between flex cable and J-block is exampled in Figure 1 below. As the dashed red line circles, one can easily see that the flex cable and J-block is not actually against and connected with each other. There inevitably exits a gap between the flex cable and the J-block device, which function is designed to hold still and secure the flex cable. Because of huge inertia difference between the flex cable and J-block/actuator comb, during HDD seek operation, there exists relative large acceleration between these two components. The relative acceleration can result in "impacting" mechanism from flex cable to J-block/actuator comb inasmuch as that on slider/head arrival TMR dynamics.

Figure 1: Photograph of loss boundary between flex cable and J-block in a state of art



Page 2 of 6

Loss boundary condition between flex cable and J-block

Loss boundary condition between flex cable and J-block

Flex cable

Flex cable



This article suggests HDD manufactures to use qualified glue/adhesive material such as DP460 to make "continuous" boundary condition between flex cable and J-block. Its relative location is depicted in Figure 2 where a state of art HDD actuator and flex cable assembly is shown.

Figure 2:...