JPH0729657A - Flexible printed board for magnetic recording device - Google Patents

Abstract

PURPOSE:To provide a subminiaturized flexible printed board having a higher density which is directly connectable to a magnetic head and its control circuit by protruding a conductor pattern from the end part of a base having the conductor pattern nipped by insulator layers to form a beam lead. CONSTITUTION:A flexible printed board A has a base body (a) having a conductor pattern 2 nipped by insulator layers 1, 3, and the pattern 2 is protruded from the end part side surface of the body (a) to form a beam lead 4. Thus, the beam lead having a minute width and an extremely fine pitch can be provided to allow the direct connection to a miniaturized magnetic head and its control circuit part. As the base 1, a one 1-200mum in thickness of polyimide resin which has a linear expansion ratio suitable to the pattern 2 consisting of a good conductive metal such as gold, silver or copper to prevent chamfer, and has satisfactory heat resistance and mechanical strength is preferably used to impart flexibility and workability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed board suitable for connecting a magnetic head of a magnetic recording device and a control circuit section.

[0002]

2. Description of the Related Art In recent years, magnetic recording devices have become larger in capacity and smaller in size, and further miniaturization is expected to continue in the future.
Conventionally, a flexible printed circuit board having flexibility has been used for a signal transmission path between a magnetic head and a control circuit unit in a magnetic recording device in order to cope with miniaturization. For connection with the substrate, soldering is performed using an insulated conductor.

[0003]

However, there is a problem that it is difficult to find a connection failure such as a disconnection in the soldering connection using the insulated conductor as described above. Further, if the magnetic head or the control circuit section is further miniaturized in the future, the electrode sections of these components will be minute and have an extremely fine pitch, and it will be difficult to interpose an insulated conductive wire that requires soldering in the connection. Therefore, it is necessary to directly connect the flexible printed board to the magnetic head and the control circuit section.

An object of the present invention is to solve the above-mentioned problems, and in particular, a flexible printed circuit board which can be directly connected to a magnetic head of a magnetic recording apparatus such as a hard disk drive which is required to be miniaturized at a high density and its control circuit section. Is to provide.

[0005]

The present inventors have made direct connection to the magnetic head and its control circuit section by projecting the conductor circuit pattern of the flexible printed board from the end side surface of the board. And the present invention has been completed. That is, the present invention is a flexible printed circuit board used for connecting a magnetic head of a magnetic recording device such as a hard disk drive and a control circuit section, in which the substrate body has a conductor pattern sandwiched between a plurality of insulator layers. A flexible printed circuit board is characterized in that the conductor pattern is projected from a side surface of an end portion of the substrate body to form a beam lead.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. Needless to say, the present invention is not limited to this. FIG. 1 is a partially cutaway perspective view schematically showing an embodiment of the flexible printed circuit board of the present invention. In the figure, A is a flexible printed circuit board of the present invention, in which a conductor pattern 2 is sandwiched between insulator layers 1 and 3 to form a substrate body a.
The conductor pattern 2 projects from the side surface of the end of the beam lead 4 and is formed. In addition, as shown in FIG.
(B) is a perspective view which shows typically the other Example of the flexible printed circuit board of this invention. 1 is different from FIG. 1 in that one of the insulating layers of the conductor pattern 2 projects with the conductor pattern 2 to form a beam lead 4. By using the flexible printed circuit board having such a structure, a beam lead having a minute width and an extremely fine pitch can be obtained, and a direct connection can be made even to a miniaturized magnetic head and its control circuit section.

The insulator layers 1 and 3 sandwiching the conductor pattern 2 are
Although they may be similar in shape and properties, it is usually preferable to use one layer as a base substrate and the other layer as a protective film. The insulator layer serving as the base substrate substantially determines mechanical properties such as strength, elasticity, and flexibility of the flexible printed circuit board A, while the layer serving as the protective film is formed on the surface of the conductor pattern 2. The protection and insulation are maintained, but the functions and roles of both may be distributed according to the purpose. For example, even if it is a protective film,
For example, it plays a role in mechanical strength. In this embodiment, for convenience, one insulator layer is referred to as the base substrate 1 and the other insulator layer is referred to as the protective film 3.

The base substrate 1 may be of any type as long as it is in contact with the conductor pattern 2 in an insulating manner, and may be a single layer or a plurality of laminated layers made of an insulating material, or a laminated layer having a metal shield layer inside. Etc. are illustrated.
As the insulating material, polyester resin, epoxy resin, urethane resin, polystyrene resin, polyethylene resin, polyamide resin, polyimide resin, A
Any thermosetting resin or thermoplastic resin such as BS resin, polycarbonate resin, or silicone resin can be used.
Of the above-mentioned insulating substances, polyimide resin is used as a material that has good heat resistance and mechanical strength and that can adapt the linear expansion coefficient to the conductor pattern 2 to prevent curling and warping during pattern formation. It is preferable to use. The thickness of the base substrate 1 is 1 to 200 μm, preferably 10 to 100 μm, in order to impart good workability and flexibility to the flexible printed board.

The protective film 3 may be of any type as long as it functions to protect the surface of the conductor pattern 2 and maintain insulation. Further, although the same material and structure as the above-mentioned base substrate may be used, it is preferable to use a polyimide resin from the viewpoint of heat resistance. The protective film 3 is formed by adhering an insulating film formed in advance to the base substrate and the conductor pattern by adhesion of an adhesive or itself, or directly by using a known thin film forming method such as coating or vapor deposition. May be

The conductor pattern 2 is a circuit pattern made of a good conductor metal, and is particularly preferable as a material, such as gold, silver, and copper, as well as platinum, nickel, aluminum, iron, chromium,
Other than molybdenum, tungsten, zinc, tin, or alloys thereof, for example, a multilayer structure made of the above-mentioned good conductor metal such as gold plating or solder plating on a circuit pattern made of copper foil may be used. Further, this multi-layer structure may be provided only in a portion related to connection such as a terminal portion. The pattern shape of the conductor pattern 2 depends on the other component to be connected, the number of circuits, the width of one circuit,
Pitch and thickness can be freely selected. Conductor pattern 2
May be sandwiched between insulating layers after being formed in an independent process, or may be formed on a base substrate by etching or vapor deposition like a known printed circuit board. .

The beam lead is an extension of the above-mentioned conductor pattern 2 and is provided on the side surface of the end portion of the substrate main body a so that it can be directly connected to the magnetic head which is miniaturized at a high density or its control circuit portion. The conductor pattern 2 is projected from the. The beam lead may be formed only on one side so as to be directly connected to only one component, as in 4a of FIG. 1, and may be directly connected to both the magnetic head and the control circuit section. As shown in FIG. 4b, the protrusion may be formed from the opposite end.
The protruding length of the beam lead is suitably selected according to the type of component and the positional relationship with the component, and is not specified. In the method of forming the beam lead, when the conductor pattern 2 is formed by an independent process and then sandwiched by the insulating layers, the conductor pattern 2 may be sandwiched so as to protrude from the end. Further, for the already formed substrate body a, the insulating layer may be removed by using a known method, and processing by laser light is particularly exemplified as an effective method in terms of accuracy and workability. An ultraviolet laser light represented by an excimer laser is useful.

The flexible printed circuit board according to the present invention is not only particularly usefully used for a minute magnetic head of an ultra-miniaturized magnetic recording device represented by a hard disk device, but also for general-purpose magnetic signals for analog signals. It can also be used for heads and special magnetic heads such as magneto-optical disks.

The control circuit section is for applying a signal to be recorded or a signal for erasing to the magnetic head or for receiving a signal from the magnetic head. As the mode of the control circuit unit, various ones such as a block composed of a plurality of electronic components, one integrated on one chip, or an intermediate one of these are exemplified. Especially 1
For a control circuit unit integrated on a chip, the flexible printed circuit board of the present invention can be used as a TAB film, and a circuit chip formed on a silicon wafer can be mounted on the flexible printed circuit board of the present invention. Can be implemented directly. That is, the flexible printed circuit board of the present invention is most effective for direct connection between both the magnetic head and the control circuit section when both are minimized.

As a method for connecting the beam lead and the magnetic head or the control circuit portion thereof, a known bonding method such as welding or pressure bonding is used.

[0015]

As described above in detail, the flexible printed circuit board of the present invention can be directly connected to the magnetic head of the magnetic recording apparatus which is miniaturized at a high density and its control circuit section. In particular, when both the magnetic head of the hard disk drive and the control circuit section are both minimized, the direct connectivity is most effective.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view schematically showing an embodiment of a flexible printed circuit board of the present invention.

FIG. 2 is a perspective view schematically showing another embodiment of the flexible printed board of the present invention.

[Explanation of symbols]

 A flexible printed circuit board a board body 1 base board 2 conductor pattern 3 protective film 4 beam lead

Claims (3)

[Claims] 1. A flexible printed circuit board used for connecting a magnetic head and a control circuit section of a magnetic recording apparatus, wherein a substrate body is formed by sandwiching a conductor pattern between insulating layers, and an end side surface of the substrate body. A flexible printed circuit board, characterized in that the conductor pattern is projected therefrom to form a beam lead. 2. The one insulating layer sandwiching the conductor pattern,
2. The flexible printed circuit board according to claim 1, wherein a beam lead is formed so as to project together with the conductor pattern. 3. The flexible printed circuit board according to claim 1, wherein the magnetic recording device is a hard disk device.