# US 11,908,497 B2 · Hard disk drive suspension pad pre-solder sidewalls

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- Number: US 11,908,497 B2
- Document ID: US11908497B2
- Status: Granted
- Kind: B2
- Application number: 17/707,368
- Filed: 2022-03-29
- Published: 2023-10-05
- Granted: 2024-02-20
- Earliest claimed: 2022-03-29
- Assignees: Western Digital Technologies, Inc.
- Applicants: Western Digital Technologies, Inc.
- Inventors: Irizo Naniwa; Kenichi Murata
- Web page: https://patentgrep.com/patent/US11908497B2

## CPC

- G11B 5/4853: {Constructional details of the electrical connection between head and arm}
- H05K 3/3442: {having edge contacts, e.g. leadless chip capacitors, chip carriers}
- G11B 5/486: {with provision for mounting or arranging electrical conducting means or circuits on or along the arm assembly}
- G11B 5/484: {Integrated arm assemblies, e.g. formed by material deposition or by etching from single piece of metal or by lamination of materials forming a single arm/suspension/head unit}
- H05K 1/117: {Pads along the edge of rigid circuit boards, e.g. for pluggable connectors}
- H05K 3/3452: Solder masks
- H05K 3/403: {Edge contacts; Windows or holes in the substrate having plural connections on the walls thereof (H05K3/4092 takes precedence)}
- H05K 2201/10159: Memory
- H05K 2201/10727: Leadless chip carrier [LCC], e.g. chip-modules for cards
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A hard disk drive flexure assembly includes a base layer, a conductive layer, a plurality of electrical pads over the conductive layer, and a sidewall layer including sidewalls on each side of and extending higher than a corresponding electrical pad. Pre-solder bumps are formed between the sidewalls and over each pad. Use of sidewalls prevents the pre-solder bumps from undesirably bridging to an adjacent electrical pad and forming a short circuit, which might otherwise cause head-gimbal assembly (HGA) manufacturing failures and consequent increased cost. These techniques are especially relevant with narrow, high-density, small pitch electrical pads.

## Claims

### Claim 1

A flexure for a suspension assembly for a hard disk drive (HDD), the flexure comprising:
an insulative base layer;
a first conductive layer over at least a portion of the base layer;
a plurality of electrical pads each comprising a second conductive layer over the first conductive layer;
a sidewall layer over a cover layer over the first conductive layer, the sidewall layer comprising:
a first sidewall adjacent to one side of and extending higher than a corresponding electrical pad of the plurality of electrical pads, and
a second sidewall adjacent to an opposing side of and extending higher than the corresponding electrical pad; and
a pre-solder bump of solder material positioned over and in contact with each of the electrical pads and substantially between each respective first and second sidewalls.

### Claim 2 (depends on 1)

The flexure of claim 1, the sidewall layer further comprising:
a root portion extending along a root end of the plurality of electrical pads.

### Claim 3 (depends on 1)

The flexure of claim 1, wherein:
each first and second sidewall comprises a tip end that extends beyond a tip end of the corresponding electrical pad.

### Claim 4 (depends on 3)

The flexure of claim 3, wherein:
each pre-solder bump extends beyond the tip end of the corresponding electrical pad.

### Claim 5 (depends on 3)

The flexure of claim 3, wherein:
each first and second sidewall comprises a root end that extends beyond a root end of the corresponding electrical pad.

### Claim 6 (depends on 5)

The flexure of claim 5, further comprising:
a step structure positioned by at least one of the tip end and the root end of the plurality of electrical pads and having a height greater than that of the electrical pads and less than that of the first and second sidewalls.

### Claim 7 (depends on 6)

The flexure of claim 6, wherein:
each pre-solder bump extends onto each step structure.

### Claim 8 (depends on 1)

The flexure of claim 1, further comprising:
a step structure positioned along a tip end of the plurality of electrical pads and having a height greater than that of the electrical pads and less than that of the first and second sidewalls.

### Claim 9 (depends on 8)

The flexure of claim 8, wherein:
each pre-solder bump extends beyond the tip end of the corresponding electrical pad and onto the step structure.

### Claim 10 (depends on 1)

The flexure of claim 1, wherein each first and second sidewall comprises:
a tip end that does not extend to a tip end of the corresponding electrical pad; and
a root end that does not extend to a root end of the corresponding electrical pad.

### Claim 11 (depends on 10)

The flexure of claim 10, wherein each tip end and root end of each first and second sidewall has a tapered or rounded shape.

### Claim 12 (depends on 11)

The flexure of claim 11, wherein a top surface of each first and second sidewall has a tapered or rounded shape.

### Claim 13 (depends on 10)

The flexure of claim 10, wherein a top surface of each first and second sidewall has a tapered or rounded shape.

### Claim 14

A method for manufacturing a flexure assembly for a hard disk drive, the method comprising:
forming an insulative base layer;
forming a first conductive layer over at least a portion of the base layer;
forming a plurality of electrical pads each comprising a second conductive layer over the first conductive layer;
forming a sidewall layer over a cover layer over the first conductive layer, the sidewall layer comprising:
a first sidewall adjacent to one side of and extending higher than a corresponding electrical pad of the plurality of electrical pads, and
a second sidewall adjacent to an opposing side of and extending higher than the corresponding electrical pad,
forming a pre-solder bump of solder material positioned over and in contact with each of the electrical pads and substantially between each respective first and second sidewalls.

### Claim 15 (depends on 14)

The method of claim 14, wherein forming the pre-solder bump includes forming the pre-solder bump employing a solder plating process.

### Claim 16 (depends on 14)

The method of claim 14, wherein forming the pre-solder bump includes forming the pre-solder bump employing a solder paste printing and reflow process.

### Claim 17 (depends on 14)

The method of claim 14, further comprising:
electrically connecting the plurality of electrical pads to corresponding electrical pads of a head slider employing laser irradiation of the pre-solder bumps.

### Claim 18

A hard disk drive (HDD) comprising:
a disk medium rotatably mounted on a spindle;
a suspension assembly comprising a flexure comprising:
an insulative base layer,
a first conductive layer over at least a portion of the base layer,
a plurality of electrical pads each comprising a second conductive layer over the first conductive layer,
a sidewall layer over a cover layer over the first conductive layer, the sidewall layer comprising:
a first sidewall adjacent to one side of and extending higher than a corresponding electrical pad of the plurality of electrical pads, and
a second sidewall adjacent to an opposing side of and extending higher than the corresponding electrical pad, and
a pre-solder bump of solder material positioned over and in contact with each of the electrical pads and substantially between each respective first and second sidewalls;
a head slider housing a read-write transducer configured to read from and to write to the disk medium, the head slider mounted on the suspension assembly and electrically connected to the plurality of electrical pads of the flexure via the pre-solder bumps; and
means for moving the head slider to access portions of the disk medium.

### Claim 19 (depends on 18)

The HDD of claim 18, wherein the sidewall layer of the flexure further comprises a root portion extending along a root end of the plurality of electrical pads.

### Claim 20 (depends on 18)

The HDD of claim 18, wherein:
each first and second sidewall comprises a tip end that extends beyond a tip end of the corresponding electrical pad; and
each pre-solder bump extends beyond the tip end of the corresponding electrical pad.

### Claim 21 (depends on 20)

The HDD of claim 20, wherein:
each first and second sidewall comprises a root end that extends beyond a root end of the corresponding electrical pad;
the flexure further comprises a step structure positioned by at least one of the tip end and the root end of the plurality of electrical pads and having a height greater than that of the electrical pads and less than that of the first and second sidewalls; and
each pre-solder bump extends onto each step structure.

### Claim 22 (depends on 18)

The HDD of claim 18, wherein:
the flexure further comprises a step structure positioned along a tip end of the plurality of electrical pads and having a height greater than that of the electrical pads and less than that of the first and second sidewalls; and
each pre-solder bump extends beyond the tip end of the corresponding electrical pad and onto the step structure.

### Claim 23 (depends on 18)

The HDD of claim 18, wherein:
each first and second sidewall comprises:
a tip end that does not extend to a tip end of the corresponding electrical pad, and
a root end that does not extend to a root end of the corresponding electrical pad;
each tip end and root end of each first and second sidewall has a tapered or rounded shape; and
a top surface of each first and second sidewall has a tapered or rounded shape.