Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
2000-12-21
2004-03-30
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S264200
Reexamination Certificate
active
06714383
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic disk apparatus, and more particularly relates to a technique that is effectively applied to a magnetic disk apparatus having a semiconductor chip on an arm of a carriage mechanism.
A magnetic disk apparatus, which is to be incorporated in a personal computer or an electronic system of a network system server, mainly comprises a disk-shaped magnetic recording medium that is rotated at high speed by a spindle motor (referred to as magnetic disk hereinafter), a magnetic head for writing (recording) the data in a magnetic disk and for reading out (reproducing) the data written in a magnetic disk, a carriage mechanism for moving the magnetic head to an arbitrary position on a magnetic disk, a semiconductor chip (referred to as read/write semiconductor chip hereinafter) in which an amplifier circuit for amplifying the analog signal read out by means of the magnetic head, an A/D circuit for converting the analog signal that has been amplified by means of the amplifier circuit to the digital signal, and a control circuit or the like for controlling various signal are incorporated, and these components are contained in a single housing.
The carriage mechanism comprises an actuator and an arm for transmitting the power of the actuator to the magnetic head. The arm comprises a root part (carriage portion) fixed to a rotation shaft that is rotated by means of the actuator, an arm body portion that is continuous to the root part of the arm, and a suspension portion that is continuous to the arm body portion that has the magnetic head. The suspension portion usually comprises a separate parts different from the arm body portion, and is attached to the arm body portion by means of a fixing means.
The magnetic head comprises a writing head for writing the data in a magnetic disk, a reading head for reading out the data written in a magnetic disk, and a slider for generating the floating force by means of air flow due to rotation of a magnetic disk. The magnetic disk floats with a small distance from the recording surface of a magnetic disk by means of floating force due to the slider and deflection of the suspension portion of the arm, and the data is written or read out in this floating state.
Usually, the front side and back side of a magnetic disk that are opposed to each other are used as the recording surface for recording the data, and a plurality of magnetic disks are piled up with interposition of a predetermined space, a plurality of arms and magnetic heads corresponding to the number of recording surfaces are used.
In such a magnetic disk apparatus, the wire wiring in which wire is fixed along an arm has been employed as the connection means for electrical connection between a magnetic head and a read/write semiconductor chip. However, in order to enhance the productivity and realize the high data transfer speed, recently electrical connection between the magnetic head and the read/write semiconductor chip, in which wiring member formed by thin film forming technique is formed on an arm is employed as a trial. This technique is described in, for example, Nikkei Electronics, issued on April 1998, 6, (No. 713), pp. 167-177, by Nikkei BP.
A method is employed as a trial, in which a semiconductor chip (referred to as amplifier semiconductor chip hereinafter) containing a built-in amplifier circuit for amplifying the analog signal read out by means of a magnetic head and a built-in A/D conversion circuit for converting the analog signal amplified by means of the amplifier circuit to the digital signal is located on the suspension part of the arm or body part of the arm and a semiconductor chip (referred to as control semiconductor chip hereinafter) containing a built-in control circuit for controlling various signals is located on the root part of the arm. Such technique is described in, for example, Japanese Published Unexamined Patent Application No. Hei 11(1999)-195202 (published Jul. 21, 1999).
SUMMARY OF THE INVENTION
In this method in the case that an amplifier semiconductor chip is located on the suspension part of the arm or located on the arm body part, a method is employed generally, in which the semiconductor chip is fixed on the chip fixing area of the wiring member so that the back surface opposed to the circuit forming surface of the semiconductor chip is facing to the wiring member, thereafter an electrode (bonding pad) formed on the circuit forming surface of the semiconductor chip is electrically connected to the wiring of the wiring member by use of a bonding wire, and resin is coated on the semiconductor chip and bonding wire for covering to protect the circuit forming surface of the semiconductor chip and the bonding wire (simply referred to as face up method hereinafter).
However, in the case of the face up method, because the thickness of the resin coated on the circuit forming surface of the semiconductor chip is inevitably thick correspondingly to the loop height (height from the circuit forming surface of the semiconductor chip to the top in the perpendicular direction) of the bonding wire, it is required to widen the space between magnetic disks, and such structure brings about the difficulty in designing the thin magnetic disk apparatus. Furthermore, because the signal transmission path between the electrode of the semiconductor chip and the wiring of the wiring member is inevitably long, such structure also brings about the difficulty in designing the high rate data transfer.
A method (simply referred to as face down method hereinafter) described hereinafter may be effectively employed in the case that an amplifier semiconductor chip is located on the suspension part of an arm or on the arm body part, in which an electrode of the semiconductor chip is electrically connected to a wiring of a wiring member with a projection electrode interpolated between the electrode of the semiconductor chip and the wiring of the wiring member and resin is filled between the semiconductor chip and the wiring member for covering the circuit forming surface of the semiconductor chip and the projection electrode to protect the circuit forming surface and the projection electrode. In the case of the face down method, the height of the projection electrode offsets the thickness of the resin, the space between magnetic disks can be narrower than that in the case of the face up method, and the thickness of the magnetic disk apparatus can be smaller. Furthermore, because the signal transmission path between the electrode of the semiconductor chip and the wiring of the wiring member is shorter in comparison with that in the case of the face up method, the higher data transfer rate can be realized.
However, the face down method is involved in a problem as described hereinafter. A semiconductor chip mainly comprises a semiconductor substrate formed of, for example, single crystal silicon. Such semiconductor chip is generally formed by means of a process in which a plurality of chip forming areas are formed on the circuit forming surface of a semiconductor wafer (semiconductor substrate) and the semiconductor wafer is diced, and the plurality of chip forming areas are divided into individual areas. Because a semiconductor substrate formed of single crystal silicon is hard and brittle, many small broken and cracks are formed on the edge portion of the circuit forming surface side (corner where the cut surface and the circuit forming surfaces intersect) and edge portion on the back side (corner where the cut surface and the back surface intersect) of the semiconductor chip divided by dicing. Because the broken and crack can cause fragments (silicon dust) separated from the semiconductor substrate, the semiconductor chip is apt to release debris.
In the case of the face down method, because the edge portion on the circuit forming surface side of the semiconductor chip is covered with resin filled between the semiconductor chip and the wiring member, the release of debris from the edge portion on the circuit forming surface sid
Kado Yoshiyuki
Kikuchi Hiroshi
Yoshida Ikuo
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Tupper Robert S.
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