JPS6381620A - Attenuation type magnetic head arm assembly - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved magnetic head arm assembly, and more particularly to a magnetic head arm assembly having a flexible circuit connection between a head and an arm cable. It is related to.

(Prior Art/Problems to be Solved by the Invention) A magnetic head arm assembly is used to access various data tracks on a rotating magnetic disk from the radial direction. Another force is applied to change the spatial position of the head translation gap.

Undesirable radial and circumferential forces are exerted when the head starts and stops in close proximity to the rotating disk. Circumferential force is created by frictional drag, and this force affects the movement of the head. A yaw moment usually appears as a secondary effect.

To maintain reasonable read and write parameters, head distances are kept small, 15 microns or less.

The magnetic head assembly described in Watrous U.S. Pat. No. 3,931,641 provides flexibility for pitch about a longitudinal axis and roll about an axis perpendicular to the longitudinal axis, and , radial,
Maintains strength and rigidity against circumferential and yaw motion.

In the head mount described in U.S. Pat. No. 4,208,684 to Janssen et al., a pivoted rigid head support arm is controlled by an offset spring that is offset relative to the rigid head support arm It has a relationship of attenuating the action and pressing with flexibility. This results in an elasticity of the support arm, which may result in vibrations of the support arm and transmission of this vibration to the transducer.

Another attempt to further limit radial, circumferential, and yaw motion to allow desirable flexibility in roll and pitch motion is disclosed in Watrous U.S. Pat. No. 4,167.7.
No. 65 and King, US Pat. No. 4,399,476.

All magnetic head assemblies have a magnetic head at one end. The other end is attached to the actuator assembly. Electrical connections must be made between the head and the actuator assembly. Currently, individual thin conductive wires are twisted together and threaded through a hollow flexible tube that runs between the actuator assembly and the head. This tube is held on the suspension arm by a central tongue or small fork.

In such a structure in which a conductor is passed through a tube, the presence of the tube strengthens the suspension.

The tube deforms to fit into the small fork and central tank, which is then held down by pushing down on the tube. Tubes threaded through fine wire within 0.01 inch (432 microns) in diameter may be cut or otherwise damaged. The height of the forks is also undesirable when stacking discs. It becomes difficult to equalize operating parameters.

An object of the present invention is to provide an electrical connection between an actuator assembly and a magnetic head without using a structure in which a conductive wire is passed through a tube. Passing the conductor within the tube is undesirable because the conductor has a tendency to break due to being forced or bent with harsh handling into the small fork and central tank. It is also required to solder thin conductive wires to the terminal pads. For shielding purposes, the individual thin conductors are twisted together to allow the conductors to pass through the tube. Such twisting is of course difficult to control, especially when the conductor has to be threaded through narrow tubes.

Another object of the invention is to eliminate the need for a "small fork" or central tank on the load beam.

Yet another object is to provide an electrical path between the actuator assembly and the head that dampens resonances in the load beam structure.

(Means/Operations for Solving the Problems) The present invention provides an electrical connection between the actuator assembly and the head, and in some forms, this connection is similar to that commonly found in structures where a conductor is passed through a tube. Excellent R
Can give F shield.

The magnetic head assembly according to the present invention includes a suspension system, and a flexible electric circuit is attached to the suspension of the suspension system using an adhesive. Both ends of the flexible circuit have exposed copper traces that are bonded to the slider terminal pads, which are attached to the terminal pads of the arm attached to the head and main cable. The exposed copper traces are bonded to the head and terminal pads by wire bonding solder, conductive epoxy, or other suitable means for making electrical connections between the conductors.

The magnetic head assembly of the present invention, which uses a flexible circuit, is more reliable than conventional magnetic head assemblies, is built into a shield, and is less expensive to manufacture than magnetic head assemblies that use a conventional tube-in-tube structure. It's cheap. The magnetic head assembly according to the present invention provides a vibration damping effect that can be manufactured to order depending on the application. Adhesive bonding of the flexible circuit to the suspension can be varied so that portions of the flexible circuit are not in direct contact with the suspension assembly. A small loop may also be added to the flexible circuit adjacent to the preload range zone of the suspension arm to minimize the influence of the flexible circuit on the durum load of the suspension arm. This loop can be designed to have a neutral effect due to the spring nature.

(Example) The invention will now be explained in detail with reference to the drawings.

FIG. 1 shows a conventional magnetic herad suspension arm assembly lO. The assembly 10 includes a slider 12 connected to a thin insulated wire 14 threaded through a polytetrafluoroethylene tube 16. The tube 16 has a small fork 20 attached to the arm 18.
and a central tongue 22. As previously discussed, the small fork and center tongue are highly undesirable because they can damage the insulated wire 14 and are relatively large, limiting stacking of the discs.

Further, the conventional assembly IJIO has a tongue and a fork, so it is not easy to manufacture. Assemblies such as that shown in FIG. 1 typically have undesirable resonant characteristics. There is a need in the industry for a suspension arm that generally has maximum vibration damping characteristics at 2000 Hp in the first bending mode. Although designs that run insulated wire within the tube tend to add damping effects, it is difficult to manufacture the illustrated assembly 10 with adequate resonant characteristics.

The suspension arm according to the invention has a very low profile, as shown in FIGS. 2-5.

Furthermore, the present invention provides damping without damaging the conductor.

The arm 100 shown in FIG. 2 has several strands 102 extending between an actuator (not shown) and a thin film slider or head 104. These strands 102 are not held in place by a fork or central tongue. Instead, strands 102 are held to suspension arm 100 by a non-viscoelastic adhesive 106. Adhesives that can be used include silicone rubber, pressure sensitive adhesives, and chemically cured polyurethanes such as Adhesive PUT, 1564, manufactured by Products Research and Fist Chemical Corporation, Glendale, Calif. . A suitable elastomeric adhesive is adhesive manufactured by V. Hordeman Company, Belleville, New Chassis, USA under the trade name Calex.

The strands 102 are connected to the arm 100 over the entire length of the arm.
The chips can be spaced apart at predetermined intervals and bonded with adhesive. By joining the strands to the arms with layers or points of adhesive, the need for forks and tongues can be eliminated and vibration damping can be provided in a circular and torsional manner. The width voltage required to reach resonance is also increased by the adhesive that bonds the strands in place.

A preferred embodiment of the invention is shown in FIGS. 3-5.

Similar to the embodiment shown in FIG. 2, the suspension arm 2oo of the present invention shown in FIGS. 3-5 eliminates the need for a small fork and a center tank. A flexible circuit 204 electrically connects the arm assembly and slider head 202 .

Flexible circuit 204 has copper traces 206 that are insulated with flexible film 208. The flexible film 208 can be formed from a polyimide, such as a polyimide film under the trade name Kapton V, or a polyester, such as a flexible polyester film under the trade name Mylar, both of which are manufactured by Kapton V and Mylar, Praue, United States. , a product of the E.I. Duhon de Nemours Company of Wilmington. The thickness of the film layer is typically 1 to 3 mils (25 to
76 microns).

The conductors 206 may be individual copper traces or individual conductive paths may be provided by etching slots into a thin copper layer as is known in the art. As shown in FIG. 5, the profile of the flexible circuit 204 is very low, much lower than that possible with an insulated wire-in-tube design. By stacking disks and heads with suspension arms according to the invention, the available space can be significantly reduced.

Flexible circuit 204 is attached to the bare suspension arm by viscoelastic adhesive 210.

In general, any adhesive that can adhere to the flexible circuit and utilize at least some elasticity after curing may be used. Pressure-sensitive adhesives, silicone comb adhesives, and urethane-based adhesives are all suitable. Products Research & Chemical Co., Ltd., Glendale, California
PR1564, a chemically cured polyurethane-based adhesive manufactured by Co., Ltd., cures to a flexible, cold flow resistant rubber that has good adhesion and vibration damping properties.

Elastomeric adhesives manufactured by H.V. Hardman Company of Belleville, New Chassis under the trade name Calex are also suitable for purposes of this invention.

Adhesive 210 may be applied to the suspension arm along the entire length of contact between the suspension arm and the flexible circuit. Alternatively, adhesive may be applied to secure the flexible circuit to the suspension arm at spaced intervals.

Since the adhesive itself provides vibration damping, if the adhesive further tightens the flexible circuit and the surface of the suspension arm, it will provide increased vibration damping.

The thickness of adhesive layer 210 can vary depending on the adhesive strength and vibration damping properties of the adhesive. Typically 1-6
Mil (25-152 microns) thick adhesive layer 210
is formed between the flexible circuit 204 and the suspension arm.

The low profile of the suspension arm according to the invention can be further reduced by modifying the basic suspension arm by reducing its rail height. Alternatively, the suspension arm could be formed as a laminate of multiple reinforcing layers to control pitch, roll and yaw characteristics as desired. Since there is no need for the invention to provide a small fork or a central tank, there is no need for the suspension arm to be made of stamped metal material.

As shown in FIG. 3, a loop 220 is formed in the flexible circuit 204 with a preload zone 222 as a load beam of the suspension arm to minimize the influence of the flexible circuit on duram loads of the suspension arm assembly. Can be done. Another means of reducing the effect of duram loading on the flexible circuit is to provide through holes in the suspension arm in the preload zone. This allows the flexible circuit to be routed between the head 202 and the actuator through either hole or both sides.

Electrical connections between the conductive traces of the flexible circuit and the head or actuator can also be made by thermocompression, ultrasonic welding, soldering, or conductive epoxy.

The vibration damping effect obtained by the present invention is shown in the following table. The table compares the bending and torsional mode frequencies and amplitude voltages when resonance occurs between a conventional suspension arm without conductive wires and a suspension arm according to the present invention in which twisted conductive wires are bonded using a polyimide flexible film with the trade name Kapton V. and show. The entire length of the flexible vibration damping suspension arm of the present invention is provided with a 2 mil (50 micron) polyimide layer and a 4 mil (102 micron) adhesive layer.

Frequency (Ht) Amplitude voltage (V) 1st bending mode 2160 1800 1.75 13.5 2nd bending mode 3440 42
-1st torsion mode 2624 2360 0.7
2.0 2nd twist mode 5730 5520
1.3 2.0 As mentioned above, the damped suspension arm according to the present invention resonates at frequencies below 2000 HJ. The table also shows that the attenuated section requires higher input energy than the standard one to reach the predetermined deflection amplitude.

The wires bonded to the suspension arms also exhibit superior vibration damping properties compared to traditional structures in which the wires are inserted into tubes.

(Effects of the Invention) The present invention does not require passing conductor wires into tubes or providing a small fork or a central tank for fixing, so electrical connections can be formed flat, and these connections can be attached to suspension arms. Since it is bonded, the vibration damping characteristics of the arm assembly can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional suspension arm assembly; FIG. 2 is a perspective view of an embodiment of the present invention utilizing stranded wire and adhesive; and FIG. 3 is a suspension arm with a flexible circuit. FIG. 4 is a side view of the arm of FIG. 3 showing the loops in the flexible circuit; FIG. 5 is a cross-sectional view of the arm taken along line 5--5 of FIG. 3; 100.200... Suspension arm (arm part) 102... Conductor wires 104, 202... Head 106.210... Adhesive 204... ...Flexible circuit 206...
......Copper trace or conductor 208...
......Flexible film 220...
......Loop (spring element) 222...
・・・・・・・・・Preload zone (load beam) patent applicant / Tsuchinnn Technology Incorporated Representative Patent attorney Yumi Tsune (and 2 others) Procedural amendment (method) August 1988 / /lI - Patent application 2 filed on August 12, 1986, name of the invention Attenuated magnetic held arm assembly 3, relationship with the amendr's case Patent applicant name Hutchinson Technology Incorporated 4, agent

Claims (1)

[Claims] 1. (a) a rigid arm portion; (b) a spring element coupled to the arm portion, reinforced and deformed in the longitudinal direction, and having a rectangular bend at its free end; (c) a load beam positioned relative to said spring element; and (d) flexible circuit means for providing electrical connections along a longitudinal axis from one end of the assembly to the other end of the assembly. , the flexible circuit means includes a plurality of conductors embedded in a thin, flexible, insulating plastic film, said film being adhesively bonded to said load beam and said rigid arm portion; A magnetic head arm assembly forming a characteristic longitudinal axis. 2. The assembly according to claim 1, wherein the plastic film is selected from the group consisting of polyimide-based and polyester-based. 3. The assembly of claim 1, wherein the adhesive is selected from the group consisting of polyurethane-based and silicone-based. 4. (a) a rigid arm portion; (b) a spring element coupled to said arm portion and reinforced and deformed in the longitudinal direction and formed with a rectangular bend at its free end; and (c) said spring. a load beam positioned relative to the element; (d) a plurality of insulated conductors making electrical connections from one end of the assembly to the other end of the assembly along a longitudinal axis thereof; A magnetic head arm assembly forming a longitudinal axis, the magnetic head arm assembly being adhesively bonded to a load beam and said rigid arm portion.