JP2007293998A - Flexible printed circuit for head gimbal assembly, head gimbal assembly, and test method of slider - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect the slider from ESD in the manufacturing and testing processes. <P>SOLUTION: The head gimbal assembly comprises a slider, a suspension supporting the slider, and a flexible printed circuit provided on the suspension and including wiring to electrically connect to the slider, a conductive tab, and a test tab 240. The flexible printed circuit includes a wiring 250 for grounding it through the test tab 240. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a head gimbal assembly (HGA) of a disk drive device for recording information, and more particularly to a flexible printed circuit of a head gimbal assembly.

  FIG. 7 shows a conventional head gimbal assembly (HGA) used in a disk drive device. As shown, the head gimbal assembly 100 includes a suspension 102 that holds a slider having a read / write magnetic element. A flexible printed circuit (FPC) 104 is attached to the suspension 102. The FPC 104 electrically connects the slider and its read / write element to a plurality of connection pads 106 connected to an external control system. In order to inspect or test the dynamic and / or static characteristics of the read / write elements provided on the slider before the HGA 100 is incorporated into the disk drive device, a test tab 108 including a test pad 109 is provided. It is electrically connected to the FPC 104.

  A magnetoresistive (MR) head or a giant magnetoresistive (GMR) head includes an MR element or a GMR element for reading data from a disk. The MR element or GMR element provided in the magnetic head is very sensitive to damage caused by electrostatic discharge (ESD). In order to prevent this damage, it is known that the MR element or the GMR element is shunted (short-circuited) by the MR element or GMR element lead (wiring) on the suspension at the time of manufacture. However, MR or GMR elements are not protected from ESD during testing.

According to Patent Document 1 in which a typical shunt system is disclosed, the shunt is released during the test. Patent Document 2 discloses a support portion in which a resin layer is laminated on both sides of a flying lead of an FPC having a long tail portion reinforced by a metal frame that reinforces the flying lead.
US Pat. No. 6,543,673 US Patent Application Publication No. 2004 / 0,228,038

  As mentioned above, there is a need for an improved system to protect sliders from ESD during manufacturing and testing processes.

  One embodiment of the present invention relates to a head gimbal assembly (HGA) that includes a flexible printed circuit (FPC) that protects a slider from ESD during manufacturing and testing processes.

  Another embodiment of the invention relates to a head gimbal assembly (HGA) that includes a flexible printed circuit (FPC) with ground wiring or ground leads.

  Another embodiment of the present invention relates to a head gimbal assembly that includes a slider, a suspension that supports the slider, and a flexible printed circuit attached to the suspension. The flexible printed circuit includes a number of wires for electrically connecting the slider to the conductive tab and the test tab. The flexible printed circuit includes a ground wiring for grounding the flexible printed circuit with a test tab.

  Another embodiment of the invention relates to a flexible printed circuit for a head gimbal assembly. The flexible printed circuit includes a plurality of wires extending from the suspension of the head gimbal assembly through the conductive tab to the test tab. The flexible printed circuit includes a ground wiring that is grounded by a test tab.

  Yet another embodiment of the present invention relates to a method for testing a slider. The method includes grounding a flexible printed circuit that electrically connects the slider to the test tab, and testing the dynamic and / or static characteristics of the slider while the flexible printed circuit is grounded. Contains.

  As described above, according to the present invention, it becomes easy to protect the slider from ESD during the manufacturing process and the test process.

  Embodiments of the present invention will be described with reference to the drawings. In each figure, like reference numerals indicate like parts. As mentioned above, the present invention aims to protect the slider from ESD during the manufacturing and testing processes. One embodiment of the present invention relates to a head gimbal assembly (HGA) including a flexible printed circuit (FPC) with ground wiring or ground leads. The grounding wiring or the grounding lead grounds the FPC during the manufacturing process and the test process in order to prevent damage due to ESD.

  1-6 illustrate an HGA incorporating an FPC according to an exemplary embodiment of the present invention. The HGA 210 includes a slider 214, a suspension 216 that supports the slider 214, and an FPC 212 attached to the suspension 216. As best shown in FIG. 1, the suspension 216 generally includes a base plate 220, a load beam 222, and a flexure 224. Base plate 220 includes mounting holes 226 that are used to connect suspension 216 to a drive arm of a voice coil motor (VCM) of a disk drive device. The shape of the base plate 220 may be different depending on the configuration and model of the disk drive device. The base plate 220 is formed of a relatively hard or highly rigid material (for example, metal) in order to stably support the suspension 216 on the drive arm of the VCM.

  The load beam 222 is attached to the base plate 220. A protrusion may be formed on the load beam 222 in order to apply a pressing load to the slider 214. The flexure 224 is welded to the load beam 222 that supports the slider 214.

  The flexure 224 is attached to the base plate 220 and the load beam 222. The flexure 224 includes a region that supports the slider 214 on the suspension 216, that is, a tongue 228. In one embodiment, the slider 214 may be supported on the suspension 216 by a known microactuator.

  As shown in FIGS. 1 and 2, the FPC 212 is attached to the flexure 224, and the slider 214 and its read / write element are connected to an external control system such as a preamplifier circuit and an external motion. Electrical connection to a test tab 240 connected to a static and / or static test system. The FPC 212 includes a grounding wiring or a grounding lead 250 (see FIGS. 3 and 4) for grounding the slider 214 during the manufacturing process and the testing process in order to prevent the slider 214 from being damaged by ESD. In the illustrated embodiment, the FPC 212 and the flexure 224 are integrated. Further, the FPC 212 and the flexure 224 are made of a stainless steel substrate in the same manner as the CIS (Circuit Integrated Suspension) or TSA (Trace Suspension Assembly) (ILS (Integrated Lead Suspension)).

  Specifically, FPC 212 includes a plurality of wires or leads 218, for example, four wires, that extend from region 228 adjacent slider 214 through conductive tab 230 to test tab 240. As illustrated, the conductive tab 230 and the test tab 240 are provided on the tail portion 260 of the FPC 212. The FPC 212 can include any suitable number of wires 218. The plurality of wirings 218 are provided on the slider 214 and its read / write element, the conductive pads 232 (for example, five pads, see FIG. 4) provided on the conductive tab 230, and the test tab 240. It is electrically connected to a test pad 242 (for example, four pads, see FIG. 3). The plurality of wirings 218 may be further electrically connected to other components in the region 228 such as a microactuator.

  In addition, FPC 212 includes ground wiring or leads 250 that extend from base plate 220 through conductive tab 230 to test tab 240. Specifically, the end 252 of the ground wiring 250 is provided on the test tab 240 as shown in FIG. The end 252 is connected to or wired to the stainless steel layer of the test tab 240 through the grounding via (first grounding via) 254. The other end portion 256 of the ground wiring 250 is provided on the base plate 220 as shown in FIG. The end portion 256 is connected to or wired to the stainless steel layer of the FPC 212 through the grounding via (second grounding via) 258. Since the FPC 212 is welded to the suspension base plate 220, the suspension base plate and test pad are well grounded. As shown in FIG. 4, the intermediate portion of the ground wiring 250 extends through the conductive pad 232 a on the conductive tab 230.

  FIG. 6 shows an embodiment of the ground via 254. As shown, the ground via 254 includes a protective layer 262, a die layer 264, and a stainless steel layer 266. As shown, the end portion 252 of the ground wiring 250 is sandwiched between these layers 262, 264, 266. The stainless steel layer 266 provided at the bottom of the grounding via 254 facilitates electrical connection for grounding and reinforces the FPC 212 around the grounding via 254. The other grounding via 258 may have the same structure.

  The ground wiring 250 is formed by ESD during the inspection of the dynamic and / or static performance of the magnetic read / write element provided on the slider 214 such as an MR head or an GMR head provided with an MR element or a GMR element. In order to prevent damage, the test tab 240, the conductive tab 230, and the base plate of the suspension are grounded. That is, the FPC 212 is electrically shunted and grounded to the test tab 240 during the testing process to prevent ESD damage.

  The grounding wiring 250 is also grounded before and after the test in order to prevent ESD damage during the manufacturing process. For example, the FPC 212 is grounded to the test tab 240 via the ground wiring 250 before the HGA 210 is tested. The FPC 212 continues to be grounded as described above during the testing process. After the test, the FPC 212 is shunted and grounded by the test tab 240 until the HGA 210 is incorporated into the disk drive device. The shunt is easily released by cutting the tail 260 between the conductive tab 230 and the test tab 240 after the conductive pad 232 is connected to an external control system such as a preamplifier circuit. be able to.

  The head gimbal assembly 210 incorporating the FPC 212 according to an embodiment of the present invention can be provided in a disk drive device (HDD). Since the structure, operation, and assembly process of the disk drive device are known to those skilled in the art, a detailed description of the disk drive device is omitted. Regardless of the HGA structure illustrated herein, the FPC 212 can be used in any disk drive device that includes an FPC and where it is desired to prevent damage from ESD.

1 is a plan view of a head gimbal assembly (HGA) including a flexible printed circuit (FPC) according to an embodiment of the present invention. FIG. FIG. 2 is an enlarged plan view of the HGA of FIG. 1 showing a tail portion of the FPC. FIG. 3 is an enlarged view of the HGA of FIG. 2 showing an FPC test tab. FIG. 3 is an enlarged view of the HGA of FIG. 2 showing an FPC conductive tab. FIG. 3 is an enlarged view of the HGA of FIG. 2 showing a base plate. FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. 3, showing a grounding via. 1 is a partial plan view of a conventional head gimbal assembly (HGA) including a conventional flexible printed circuit (FPC). FIG.

Explanation of symbols

210 Head Gimbal Assembly (HGA)
212 Flexible Printed Circuit (FPC)
214 Slider 216 Suspension 218 Wiring 220 Base plate 222 Load beam 224 Flexure 230 Conductive tab 232, 232 a Conductive pad 240 Test tab 242 Test pad 250 Grounding wire 252, 256 End 254 Grounding via (first grounding via)
258 Grounding via (second grounding via)
260 Tail 262 Protective layer 264 Die layer 266 Stainless steel layer

Claims (17)

A slider,
A suspension for supporting the slider;
A flexible printed circuit provided with a plurality of wires provided on the suspension and electrically connecting the slider to a conductive tab and a test tab;
Have
2. The head gimbal assembly, wherein the flexible printed circuit includes a grounding wiring for grounding the flexible printed circuit with the test tab.   The head gimbal assembly according to claim 1, wherein the conductive tab includes a plurality of conductive pads.   The head gimbal assembly according to claim 1, wherein the test tab includes a plurality of test pads.   4. The head gimbal assembly according to claim 1, wherein the grounding wiring extends from the suspension through the conductive tab to the test tab. 5. The grounding wiring is
A first end that is led through a first grounding via to the stainless steel layer of the test tab;
A second end leading to a stainless steel layer of the flexible printed circuit through a second grounding via;
Have
The flexible printed circuit according to any one of claims 1 to 4, wherein the flexible printed circuit and a base plate of the suspension are welded.   At least one of the first and second grounding vias includes a protective layer, a die layer, and a stainless steel layer, and the corresponding first and second ends of the grounding wiring have the protection 6. The head gimbal assembly according to claim 5, sandwiched between a layer, the die layer, and the stainless steel layer.   The head gimbal assembly according to any one of claims 1 to 6, wherein the flexible printed circuit is grounded during a test process.   The head gimbal assembly according to any one of claims 1 to 7, wherein the flexible printed circuit is grounded before being assembled into a disk drive device.   The head gimbal assembly according to any one of claims 1 to 7, wherein the flexible printed circuit is grounded after being tested and before being assembled into a disk drive device. A plurality of wires extending from the suspension of the head gimbal assembly through the conductive tab to the test tab;
Grounding wiring to be grounded with the test tab,
A flexible printed circuit for a head gimbal assembly.   The flexible printed circuit of claim 10, wherein the conductive tab includes a plurality of conductive pads.   The flexible printed circuit according to claim 10, wherein the test tab includes a plurality of test pads.   The flexible printed circuit according to claim 10, wherein the grounding wiring extends from the suspension to the test tab through the conductive tab. The grounding wiring is
A first end that is led through a first grounding via to the stainless steel layer of the test tab;
A second end leading to a stainless steel layer of the suspension through a second grounding via;
The flexible printed circuit according to claim 10, comprising:   At least one of the first and second grounding vias includes a protective layer, a die layer, and a stainless steel layer, and the corresponding first and second ends of the grounding wiring have the protection The flexible printed circuit of claim 14, sandwiched between a layer, the die layer, and the stainless steel layer. Grounding the flexible printed circuit that electrically connects the slider to the test tab; and
Testing the dynamic and / or static characteristics of the slider with the flexible printed circuit grounded;
A test method for a slider having   The test method according to claim 16, further comprising the step of maintaining the ground of the flexible printed circuit after the testing of the flexible printed circuit until before the flexible printed circuit is incorporated into a disk drive device.

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