JP2001023102A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an MR head from being broken down caused by static electricity in the HSA(head stack assembly) manufacturing process. SOLUTION: The magnetic disc device has a coil holder 3 whose conductive coil part is covered with electrostatic shielding tape and an R/W circuit mounting connector whose connection part between the connector pins and printed wiring board of its MR head connector is covered with a high resistance material with a resistance not lower than 1×105 Ω. By preventing the MR head 1 of the magnetic disc device from being charged, the MR head 1 can be prevented from electrostatic breakdown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive, and more particularly, to a magnetic disk drive having a coil holder for preventing electrostatic breakdown of an MR head and a connector mounted with an R / W circuit.

[0002]

2. Description of the Related Art In a magnetic disk drive, information recorded on a magnetic disk is read using a magnetoresistive sensor. The magnetoresistive sensor is usually referred to as "MR (Magnetic Resi
stive) sensor, and a magnetic head equipped with this MR sensor is referred to as an “MR head”. Since the MR head has high recording / reproducing sensitivity, an output signal larger than that of the conventional inductive read head can be obtained. This large output signal increases the output signal-to-noise ratio (S / N ratio), and can further increase the areal density of recorded information on the magnetic disk.

An MR head is usually manufactured on an Al ₂ O ₃ .TiC ceramic substrate. However, when the cross-sectional area of the MR head is reduced, both the film thickness and the stripe height are reduced, so that the sensitivity of the electrostatic discharge is increased. When a substance and a substance come into contact with and separate from each other, static electricity is generated in both substances. Then, the residual static electricity remains (is charged) on the insulator or the insulated conductor, and the residual static electricity is discharged at the same time as the object is touched. This is called electrostatic discharge.

A component in which a MR head is stacked together with a position control coil and a connector mounted with an R (read) / W (write) circuit, so as to be mountable on a magnetic disk drive,
It is called HSA (Head Stac Assy). In this HSA manufacturing process, the MR head is most susceptible to the effects of electrostatic discharge. In fact, there are many events in which the output of the MR sensor cannot be sufficiently obtained due to electrostatic discharge breakdown.

[0005]

The cause of the electrostatic discharge breakdown of the MR head in the HSA manufacturing process is considered as follows.

The first is charging of the position control coil.
The position control coil includes a conductive coil and a conductive coil support, and is usually called a coil holder. HS
In the A assembly process, it is necessary to handle the position control coil. When the conductive coil is touched during handling, the conductive coil is charged. However, since the conductive coil is usually surrounded by a support made of plastic, which is an insulator, there is no place for discharging static electricity, and the structure is easily charged. At the moment when the coil holder and the MR head are combined, the static electricity charged in the coil holder flows to the MR head side, causing the electrostatic breakdown of the MR sensor.

Second, there is charging of the R / W circuit mounted connector. This part consists of an integrated circuit for reading and writing signals and a connector for mounting the MR head on a printed wiring circuit (Flexbile Pri
nt circuit (abbreviation: FPC), and is commonly called FPC Assy. The printed wiring circuit is made of flexible plastic. This part needs to be bent in handling the assembly, and is charged at this time. In addition, since the bending occurs due to the shaking during the transport of the parts, the parts are charged at this time. The integrated circuit portion and the connector to which the printed wiring circuit is connected are hardened with plastic, and the printed wiring circuit is structurally surrounded by an insulator. That is, the R / W circuit mounted connector has a structure that is easily charged with static electricity. At the moment when this connector is brought into contact with the terminal portion of the MR head, the static electricity charged in the printed wiring circuit flows to the MR head side, and the electrostatic breakdown occurs.

The magnetic disk device is grounded when mounted on a personal computer. Therefore, H
After the SA is mounted on the magnetic disk device, the electrostatic breakdown of the MR head rarely occurs.

Accordingly, an object of the present invention is to prevent the MR head from being destroyed by static electricity in the HSA manufacturing process of a magnetic disk drive.

[0010]

The basic features of the magnetic disk drive according to the present invention for solving the above-mentioned problems are as follows.
That is, a mechanism for avoiding charging of the R head is provided.
More specifically, the coil holder, in which the conductive coil portion is covered with an electrostatic shielding film, and the connector portion of the MR head connector and the connection portion of the printed wiring circuit are covered with a high resistance member of 1 × 10 ⁵ Ω or more. An R / W circuit mounted connector is provided.

In a coil holder composed of a conductive coil and a conductive coil support, the conductive coil portion is covered with an electrostatic shielding film to suppress static electricity generated when the coil holder is handled.

Also, a recording information read / write device, MR
In an R / W circuit mounted connector comprising a head connection connector and a printed wiring circuit for connecting the device and the connector, the connection between the connector pin of the MR head connection connector and the printed wiring circuit is 1 × 10 ⁵
Cover with a high resistance member of Ω or more. The assembly worker wears high-resistance gloves and a wristband, and inserts the connector into the MR head terminal while touching the high-resistance member with a finger. Static electricity generated in the printed wiring circuit can escape to the outside through the high-resistance member and the wristband.
For this reason, electrostatic breakdown of the MR head when the connector is inserted can be prevented.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The HSA (Head Stac Ass) according to the first embodiment
The assembly of y) is shown in FIG.

The HSA is a component in which several MR heads are stacked together with a position control coil and a connector mounted with an R / W circuit so as to be mounted on a magnetic disk drive.

In a magnetic disk drive, information recorded on a magnetic disk is read using a magnetoresistive sensor (MR sensor). A component of the magnetic head on which the MR sensor is mounted is generally called an MR head 1. Although it is commonly called an MR head, to be precise, a magnetic head for performing R / W,
It is a part composed of a suspension part that supports the magnetic head and a wiring part that transmits information from the MR sensor.
HAA (HeA)
ad Arm Assy).

In the magnetic disk drive, a portion for moving the magnetic head to an arbitrary position is called an actuator.
The actuator mainly includes a position control coil unit and a permanent magnet unit. The position control coil includes a conductive coil and a conductive coil support, and is generally called a coil holder 3.

The recording information from the MR head is transmitted to the control circuit of the magnetic disk drive through the R / W circuit mounted connector.
And to a personal computer. This component connects a recording information read / write device 9 and a connector 6 to be attached to a terminal of the MR head by a printed wiring circuit 8, and is generally called an FPC assembly.

The assembling process of the HSA will be described.

First, several MR heads 1 and one coil holder 3 are stacked on the pivot 5. In the present embodiment, a magnetic disk device having a device capacity of 4.3 GB (gigabyte) will be described, but four MR heads are used.

After the lamination, the positions of the MR head 1 and the coil holder 3 are adjusted. After adjustment, fix the end of the pivot with a nut.

Next, the connector equipped with the R / W circuit is inserted into the head terminal 2 of the MR head. Finally, the conductor at the end of the conductive coil portion of the coil holder 3 is connected to the printed wiring circuit, and the HSA is completed.

In the above-described HSA assembling process, the following two processes are likely to generate static electricity.

First, there is a process for handling the conductive coil of the coil holder. In operation, it is necessary to handle the coil holder. Since the conductive coil is usually surrounded by a support made of plastic, which is an insulator, the conductive coil is a component that is easily charged by any contact. In the actual assembling process, the coil holder is handled and set on an assembling tool, and the charge amount of the coil holder at that time is measured.
It was about 50V. In addition, although this measurement value was measured in an ion blow environment, it is charged up to about 1000 V under the condition without ion blow.

Second, there is a process for handling the R / W circuit mounted connector. The printed wiring circuit, which is a component of the connector, is made of flexible plastic. In operation, the printed wiring circuit needs to be bent. Also,
The printed wiring circuit undergoes deformation such as bending due to shaking during transportation. The printed wiring circuit is charged by the bending and shaking. Since the integrated circuit portion and the connector to which the printed wiring circuit is connected are surrounded by an insulating plastic, the printed wiring circuit has a structure that is easily charged. Actually, during the assembly operation, the R / W circuit mounted connector was placed on the member tray and moved, and the charge amount of the printed wiring circuit at that time was about 50 V. An experiment was conducted in which the printed wiring circuit was handled and bent several times.
At this time, the charge was about 150 V.

The MR head has an electrostatic proof strength of 100 to 200.
However, in the case of a giant magnetoresistive head (GMR head) which has begun to be used in recent years in order to improve the recording density, the electrostatic withstand strength is even weaker at 20 to 50 V.

Therefore, when the MR head is brought into contact with a coil holder or a printed wiring circuit, the MR sensor is liable to cause electrostatic breakdown. In particular, the possibility of electrostatic breakdown is very high in the GMR head.

In consideration of the above, the measures shown in FIG. 2 were implemented for the coil holder.

The coil holder 3 composed of the conductive coil 13 and the conductive coil support 12 was covered with the electrostatic shielding film 4. By avoiding direct contact with the conductive coil 13, generation of static electricity is suppressed.

Although a non-conductive plastic is often used as the material of the conductive coil support 12, it is more effective to use a metal material such as aluminum as a measure against static electricity. This is because by using a metal material, static electricity charged in the conductive coil can be released.

For the connector mounted with the R / W circuit, the countermeasures shown in FIG. 3 were implemented.

FPC wiring section 16 of printed wiring circuit 8
Is connected to the connector pin 15 by soldering on the back surface of the connector 6. In this embodiment, the connection portion 14 is covered with the high resistance member cover 7 of 1 × 10 ⁵ Ω or more.

As shown in FIG. 1, the assembling worker wears the high-resistance gloves 10 and the wristband 11 and touches the high-resistance member cover 7 with a finger to connect the connector 6 to the MR head terminal 2. Plug in. In the printed wiring circuit 8, the static electricity charged before the assembling work and the static electricity generated during the assembling work can be released to the outside through the high resistance member cover and the wrist band.

Table 1 shows the improvement effect of the present invention.

[0035]

[Table 1]

The effect was confirmed with a magnetic disk device having a device capacity of 4.3 GB using a GMR head.

The following two tests were performed as confirmation tests.

First, the output voltage of the GMR head was confirmed after HSA assembly. In this test, HSA of 0.200 mV or less was regarded as defective.

Secondly, after assembling the magnetic disk drive, a read test was performed to confirm defects such as insufficient output voltage of the GMR head and output waveform asymmetry.

As shown in Table 1, the defect rate was 2
It decreased from 4.0% to 4.2% and from 46.0% to 2.6%.

[0041]

According to the present invention, the coil holder is characterized in that the conductive coil portion is covered with an electrostatic shielding film, and the connection between the connector pin of the MR head connector and the printed wiring circuit is 1 × 10 ⁵ Ω or more. By providing the R / W circuit mounted connector characterized by being covered by the high resistance member, it is possible to avoid charging the MR head of the magnetic disk drive, and thereby to prevent electrostatic breakdown of the MR head. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an HSA assembling operation according to a first embodiment.

FIG. 2 is a diagram showing a coil holder according to the first embodiment.

FIG. 3 is a diagram showing an R / W circuit mounted connector according to the first embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... MR head, 2 ... MR head terminal part, 3 ... Coil holder, 4 ... Electrostatic shielding film, 5 ... Pivot, 6
... connector, 7 ... high resistance cover, 8 ... printed wiring circuit, 9 ... device for reading and writing recorded information, 10 ... high resistance glove, 11 ... wrist band, 12 ... conductive coil support, 1
3 ... conductive coil, 14 ... connector pin / FPC connection part,
15: Connector pin, 16: FPC wiring section.

Claims (5)

[Claims] 1. A magnetic disk drive comprising a magnetoresistive head, comprising: a mechanism for avoiding charging of the magnetoresistive head. 2. A coil holder comprising a conductive coil and a conductive coil support, wherein the conductive coil portion is covered with an electrostatic shield film. 3. A magnetic disk drive using the coil holder according to claim 2. 4. A connector equipped with a read / write circuit comprising a recording information read / write device, an MR head connection connector, and a printed wiring circuit connecting the device and the connector. 1 x 1
Read / write circuit mounting connector, characterized in that covered by 0 ⁵ Omega or high resistance member. 5. A magnetic disk drive using the read / write circuit mounting connector according to claim 4.