JPH0638313B2 - Magnetic bubble memory device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a magnetic bubble memory device, in particular, thinning, miniaturization,
The present invention relates to a magnetic bubble memory device suitable for reducing power consumption and improving assemblability.

[Background of the Invention]

A magnetic bubble memory device that has been put into practical use in recent years is for generating a rotating magnetic field composed of rectangular solenoid coils having an asymmetric structure on a wiring substrate such as an E-shaped ceramic or synthetic resin on which a magnetic bubble memory chip is mounted. The structure is such that the X coil and the Y coil are respectively inserted and orthogonally arranged to be assembled. The X coil and the Y coil are not only the magnetic bubble memory chip but also a structure in which a wiring board much larger than the chip is wound, so that the length of each coil becomes long, and the driving voltage and power consumption increase. Will end up. Further, since the X coil and the Y coil are required to have a uniform inductor balance in order to apply a uniform and stable in-plane rotating magnetic field to the magnetic bubble memory device, the coil shapes thereof are different from each other and have an asymmetric structure and a large structure. I had no choice. Further, a pair of permanent magnet plates for applying a vertical bias magnetic field to the magnetic bubble memory element and its magnetic compensating plate are arranged on the outer surfaces of these X and Y coils, and their peripheral portions are covered with a resin mold. This structure increases the vertical stack thickness, which is an obstacle to the demand for thinner and smaller magnetic bubble memory devices.

As the prior art closest to the present invention known to the applicant of the present invention, there is JP-A-54-55129. This publication describes the structure of a frame-shaped core surrounding a chip and a conductive magnetic field reflection box completely surrounding them. However, no further concrete structure is shown, and it is theoretically impossible to make electrical connection to the chip completely surrounded by the conductor case without shorting it from the outside of the conductor case. It is possible, and it is insufficient from the viewpoint to think that the description will be put into practical use, including the fact that the mounting method of the permanent magnet, the magnetic shunt plate, the bias coil, etc. is unknown.

[Object of the Invention]

It is an object of the present invention to provide a magnetic bubble memory device that enables thinning and miniaturization and effectively utilizes a flexible wiring board on which a chip is mounted.

[Outline of Invention]

According to the present invention, a magnetic bubble memory chip mounted on and electrically connected to a chip mounting portion of a flexible wiring board having a chip mounting portion and an external connection terminal connecting portion is wound around two sets of two opposite sides. In a magnetic bubble memory device arranged at a position surrounded by a rectangular ring-shaped core provided with a magnetic field, the magnetic bubble memory chip, the winding and the core are covered with a rotating magnetic field confinement case. The flexible wiring board having the connection terminal connecting portion is formed into a substantially rectangular shape, so that the flexible board can be effectively utilized and the handling property and the alignment accuracy at the time of assembly can be improved.

Example of Invention

 Next, the present invention will be described in detail with reference to the drawings.

1 and 2A and 2B are views for explaining a magnetic bubble memory device which is a target of the present invention.
The figure is a partially broken perspective view, FIG. 2A is its bottom view, and FIG. 2B.
FIG. 2B is a sectional view taken along the line 2B-2B in FIG. 2A. In these drawings, CHI is a magnetic bubble memory chip (hereinafter referred to as a chip). In these drawings, the chip CHI is omitted and only one chip is shown, but in this example, two chips are arranged side by side. To do. (The chip yield is better in a multi-divided chip configuration in which the total storage capacity is matched to that of one large-capacity chip.) The FPC has two chips CHI and the chips CHI and external connection terminals at the four corners. It is a flexible wiring board (hereinafter referred to as a board) having a wire group extension for connection with.

The COI is a drive coil (hereinafter referred to as a coil), which is arranged so as to surround two chips CHI on substantially the same plane and have opposite sides parallel to each other. In FIG.
It is shown with a, 20b, 20c, and 20d attached. ), COR is a frame-shaped core (hereinafter referred to as a core) made of a soft magnetic material that is fixedly arranged so as to penetrate the hollow portion of the rectangular coil assembly COI, and the core COR and each coil COI form a chip CHI. Magnetic circuit PFC for applying in-plane rotating magnetic field
Are configured.

RFP is a rotating magnetic field confinement case (hereinafter referred to as a case) that houses the central rectangular portion of the substrate FPC, the two chips CHI and the magnetic circuit PFC as a whole. The case RFS is formed by processing two independent plates, and the upper and lower plates are electrically connected at the side surface of the case. In these cases RFS, narrowed portions (30 and 33 in FIG. 3) are formed in the peripheral portion so that the gap in the central portion becomes narrower in a range slightly wider than the portion where the chip CHI is arranged. This narrowed portion can also be used for positioning the magnet body described later. The case RFS contains a rotating magnetic field confinement and a weak substrate F.
It has the effect and function of two birds with one stone that mechanically supports the PC.

Between the case RFS and the chip CHI, especially the chip C
Although there is a gap SIR on the side surface of the HI, the gap SIR, including the flat portion of the chip CHI, is coated or filled with silicone resin, so that foreign matter may adhere to the main surface of the chip during assembly or moisture may be removed after assembly. The passivation effect is intended to reduce penetration into the main chip surface or side surfaces. If complete airtight sealing can be performed outside the case RFS, the filling of the resin SIR may be omitted.

INM is a pair of inclined plates made of a magnetic material arranged on the outside of the case RFS. In FIG. 2, the upper inclined plate INM is closer to the left and the lower inclined plate INM is closer to the right. Both of them have an inclined surface on the case RFS side. As the material of the inclined plate INM, soft ferrite or permalloy having a high magnetic permeability μ and a small coercive force Hc may be used. In this example, soft ferrite which is easy to process the inclined surface was selected. The MAG is a pair of permanent magnet plates (hereinafter referred to as magnet plates) arranged inside the pair of inclined plates INM so as to be superposed thereon. The HOM is a pair of magnetic compensating plates made of a magnetic material such as soft ferrite and arranged inside each of the magnet plates MAG so as to overlap with each other. The magnet plate MAG is formed to have a uniform plate thickness over the entire surface. The INN is a pair of inclined plates made of a non-magnetic material having good thermal conductivity, such as copper, which is arranged on the inner facing surfaces of the pair of magnetic shunting plates HOM so as to be superposed thereon. These inclined plates INN are formed to have an inclined angle substantially equal to that of the inclined plate INM and an inclined surface in the opposite direction. Inclined plate I
NM, magnet plate MAG, magnetic shunt plate HOM and inclined plate INN
Are formed such that when the bias magnetic field generating magnets BIM (hereinafter referred to as “magnets”) are formed by stacking and arranging them integrally, the laminated plate magnets have a uniform thickness over almost the entire surface. There is. A pair of magnets BIM
Is adhered to the central flat portion surrounded by the narrowed portion of the case RFS.

The BIC is a bias magnetic field generating coil (hereinafter referred to as a bias coil) arranged in a groove-shaped gap portion between the peripheral portion of the magnet body BIM and the case RFS. The bias coil BIC is driven to adjust the magnetic force of the magnet plate MAG according to the characteristics of the chip CHI or to test all the bubbles in the chip CHI for the purpose of testing for the presence or absence of defective defects in the chip CHI.

The SHI is a case RFS containing a substrate FPC on which the chip CHI is mounted and a magnetic circuit PFC, and an external magnetic shield case (hereinafter referred to as a shield case) made of a magnetic material that houses a pair of magnet bodies BIMa and BIMb and a bias coil BIC outside the case RFS. It is called). As a material for the shield case SHI, a magnetic material having a high magnetic permeability μ, a large saturation magnetic flux density Bs, and a small Hc is preferable. Permalloy and ferrite have such characteristics, but bending is suitable in this example. , A permalloy iron-nickel alloy that is strong against mechanical external force was selected.

The PKG is a packaging case made of a material such as Al, which is attached to the outer peripheral surface of the shield case SHI by adhesion or fitting and has a high thermal conductivity and is easy to process. The CNP is a contact pad that extends from the four corners of the substrate FPC and is arranged so as to come into contact with an external connection terminal that is folded back on the back surface of the shield case SHI. TEF is a terminal fixing plate made of an insulating member that supports and fixes each contact pad CNP at the stepped portion of the opening. The REG is a resin mold that is enclosed in four corners inside the packaging case PKG which is a folded portion of the FPC as shown in FIG. 1 and fixes the shield case SHI assembly, the FPC and the like inside the packaging case PKG.

FIG. 3 is an assembly perspective view for explaining a stacking and assembling procedure of the respective constituent members constituting the magnetic bubble memory device described above, and the same reference numerals as those used above denote the same members. In the figure, first, a board assembly BND in which two chips CHI are mounted on a board FPC having projecting portions 4 at the four corners and connecting portions 3 for input / output wiring and having a chip mounting portion 1 at the center is formed on the bottom surface. The insulating sheet 36 is placed inside the outer case RFSa, which is adhesively placed on the substrate FPC.
After incorporating the magnetic circuit PFC on top, silicone resin S
Inner case RFS is filled with IR (not shown)
b is incorporated in the outer case RFSa, and the side contact portions of the outer case RFSa and the inner case RFSb are electrically connected by soldering or the like.

Next, these inner case RFSb and outer case RF
After arranging the upper magnet body BIMa and the lower magnet body BIMb in the recessed diaphragm portions 30 and 33 provided on the outer surface of Sa, the outer edge portion of the upper magnet body BIMa and the inner case RF are arranged.
A bias coil BIC wound in alignment with the inside of Sb, which is not shown, is arranged and housed in an outer shield case SHIa, and an inner shield case SHIb is further incorporated to form an outer shield case SHIa and an inner shield case. The side contact portion with SHIb is magnetically connected by welding or the like.

Next, from the four corners of the shield case SHI to the outer case RFS
The external connection terminal connecting portion 3 of the substrate FPC protruding through the cutout portion 35 of a and the cutout portion 54 of the outer shield case SHIa is cutout 58 of the inner shield case SHIb.
1 and is folded back as shown in FIG. 1 with a bent portion 2 on its back side, and is arranged in combination so as to cover the entire back surface of the inner shield case SHIb.
A terminal fixing plate TEF having a contact pad CNP mounted in each opening is placed in contact with each external connection terminal 9b covered with solder or the like provided in each of the external connection terminals 9b and the contact pad by thermocompression bonding or the like. The CNP is electrically connected by soldering or the like.

Next, these assemblies are housed in the packaging case PKG, and the terminal fixing plate TEF and the packaging case PK are installed.
It is assembled by hermetically sealing the G contact portion.

A partially cutaway perspective view of the device thus assembled is shown in FIG. 1 and a sectional view is shown in FIG. 2B.

FIG. 4 is a diagram showing a substrate FPC, FIG. 4A is a plan view thereof, FIG. 4B is a plan view in which the connecting portions of the external connection terminals projecting from the four corners are arranged in a folded combination, and FIG. 4C-4C enlarged sectional view of FIG. A, and FIG. D is 4D- of FIG.
It is a 4D enlarged sectional view. In the figure, the substrate FPC is
A rectangular chip mounting part 1 in the central part, bent parts 2 (2a, 2b, 2c, 2d) with small widths at these four corners, and a rectangular external connection terminal connection part (hereinafter referred to as a connection part) at this tip part. 3)
(3a, 3b, 3c, 3d), and the overall shape is a windmill shape and is integrally formed. Also, as shown in FIG. Two chips C
Rectangular opening 4 (4a, 4b) of double frame structure for mounting HI and connecting its terminals, and three holes 5 for positioning
(5a, 5b, 5c) are provided, and further, a substrate protruding portion 6 for positioning is provided at the tip of one connecting portion 3c.

Further, as shown in FIG. 4C, the substrate FPC has a three-layer structure of substantially insulating layer-wiring layer-insulating layer, and has an epoxy on the base film 7 made of a polyimide resin film having a thickness of, for example, about 50 μm. By forming a copper thin film through a system adhesive 8 and etching it into a desired pattern shape, wiring leads 9a, circular external terminals 9b, and elliptical coils as shown in FIG. 4A. Lead connection terminal 9
Patterns such as c, symbol 9d and index mark 9e are formed, and a translucent or semi-translucent cover film 10 is adhesively arranged on the upper surface of the same through an adhesive 8 made of the same material as described above. .

Then, in the opening 4 of the substrate FPC, an opening is formed in the base film 7 on the chip CHI mounting side with high accuracy, and the upper surface side cover film 10
An opening having a relatively large size is formed in the wiring, and a wiring lead 9a is provided between the base film 7 and the cover film 10.
Is exposed, and a tin plating layer 11, for example, is formed on the surface of the wiring lead 9a, and the opening shape is formed to have a two-layer structure and a double frame structure. The chip CHI is, for example, lead-bonded on the exposed wiring lead 9a. On the other hand, in the connection portion 3, a circular opening 12 is formed in a portion of the cover film 10 corresponding to the circular external terminal 9b and the oval external terminal 9c (not shown) as shown in FIG. External terminal 9 exposed from 12
A solder layer 13 formed by plating or dipping is formed on the b, 9c copper thin film pattern. The external terminals 9b and 9c provided on these connecting portions 3 are connected to the connecting portions 3a and 3c, respectively.
b, 3c, 3d and bent portions 2a, 2b, 2c, 2d and lead wires 9a for wiring formed continuously on the chip mounting portion 1 are connected, and these wiring leads 9a are provided on the chip mounting portion 1. Each connection part 3 is provided at a part of the opening end of each of the formed openings 4a and 4b.
The blocks a, 3b, 3c, and 3d are gathered together, and their tips are exposed in the openings 4a and 4b. That is, as shown in FIG. 4A, the wiring lead 9a of the connecting portion 3a is at the upper left portion of the opening 4a, the wiring lead 9a of the connecting portion 3b is at the lower left portion of the opening 4b, and the wiring lead of the connecting portion 3c. 9a is on the upper right of the opening 4a,
Further, the wiring lead 9a of the connecting portion 3d is wired in the lower right portion of the opening 4b.

In this board FPC, the inner shield case S is formed by bending the connecting portions 3a, 3b, 3c, 3d at the bent portions 2a, 2b, 2c, 2d in the process described with reference to FIG.
Combined to cover the entire back surface of HIb, solder layer 13
Since the external terminals 9b and 9c formed with are exposed on the surface, and the surfaces of the wiring leads 9a, the symbols 9d and the index marks 9e are covered with the cover film 10, these patterns are transparent to the cover film 10. It is designed to be easy to read.

In such a configuration, a polyimide resin film is used as the substrate FPC, and the bent portions are provided at the four corners of the chip mounting portion 1.
It is configured like a wind turbine with each connecting portion 3a, 3b, 3c, 3d provided via 2a, 2b, 2c, 2d, and the external terminal portion is formed by folding and combining each of these connecting portions 3a, 3b, 3c, 3d. As a result, since the chip mounting portion 1 and the connecting portion have a two-layer wiring structure, the area of the chip mounting portion 1 can be increased without reducing the area of the connecting portion 3, and at the same time, the external terminal portion can have multiple terminals. The entire shape can be reduced.

Further, in such a configuration, the wiring lead 9a from each external terminal 9b to each opening 4a, 4b of the chip mounting portion 1 can be greatly shortened, so that the influence of external noise or the like can be greatly reduced. That is, a signal having a high S / N ratio can be input / output. Further, by providing the board projecting portion 6 at one end of the connecting portion 3c and providing the index mark 9e on the projecting portion 6, for displaying the central portion of the board when folded and assembled, the cases RFS and SHI (see FIG. 2). ), It is easy to make a determination for alignment, a type of the wiring lead 9a or a product type display, so that assembly and board management can be rationalized. Further, by providing the perforations 5a, 5b, 5c on both end sides of the chip mounting portion 1 of the substrate FPC, it becomes easy to distinguish the right and left of the substrate FPC, the positioning of the chip CHI, etc., and similarly, the assembling property can be rationalized. it can.

FIG. 5 is a plan view showing the chip CHI mounted on the above-mentioned substrate FPC. In the figure, the substrate FPC
In the chip mounting part 1 of the two chip CHI openings 4a,
A board assembly BND mounted in parallel between 4b is configured, and one chip CHI is configured by integrating two blocks of 1Mb, for example, and two chip CHIs are configured.
Then, 4 blocks make up a total of 4 Mb chips.

An object of the present invention is to effectively use a flexible board, improve handleability of the board assembly BND, and improve alignment when the external connection terminal connecting portion 3 is bent. That is, since the above-described substrate FPC has a windmill shape, the utilization efficiency of the material is low, and it is not always satisfactory in terms of handleability and alignment.

First and second embodiments of the present invention which solve the above problems are shown in FIGS. 6 and 7. In the figure, the same symbols as those in FIG. 4A indicate the same components. The basic configuration of the present invention is to make the outer shape of the substrate FPC into a substantially rectangular shape, which allows the film used as the material of the substrate FPC to be effectively used while being suppressed, and also facilitates handling during device assembly. It is something that can be improved. Further, by integrating the external connection terminal group, it is possible to improve handleability and terminal alignment accuracy.

In the embodiment shown in FIG. 6, the chip mounting portion 1 and the external connection terminal connecting portion 3 have substantially the same area, and the central portion of the boundary portion is cut out to make the width narrow, and the bent portion 2 (2a, 2b) is formed. Is used as. According to this structure, the film used as the material can be effectively utilized, and since the connection portion 3 is centralized and integrated in one place, the handling property and the alignment accuracy at the time of board assembly are greatly improved.

In the embodiment shown in FIG. 7, a pair of external connection terminal connecting portions 3a and 3b are provided on both sides of the chip mounting portion 1, and the central portion of the boundary portion thereof is cut out to make the width narrow, and the bent portion 2 (2a, 2b,
2c, 2d). According to this structure, the film made of the same material as in the embodiment of FIG. 6 can be effectively utilized, and since the connecting portion 3 is centralized and integrated in two places, the handling property and the alignment accuracy at the time of board assembly are improved. Greatly improved.

〔The invention's effect〕

As described in detail above, according to the present invention, it is possible to effectively utilize the flexible wiring board on which the magnetic bubble memory chip is mounted, and to improve the handling property and the positioning accuracy of the substrate, and to make the assembly property extremely good. Have.

[Brief description of drawings]

1 is a partially cutaway perspective view showing the entire magnetic bubble memory device in the process of reaching the present invention, FIG. 2A is a bottom view, FIG. 2B is a sectional view taken along line 2B-2B in FIG. A, and FIG. FIG. 4 is an exploded perspective view showing a stacking structure, FIG. 4 is a view for explaining a substrate FPC, and FIG. 5 is a plan view showing a substrate assembly BND in which a chip CHI is mounted on the substrate FPC. 6 and 7 are plan views showing two embodiments of the present invention. FPC: Flexible wiring board, 1: Chip mounting part, 2a, 2b, 2c, 2d ... Bent part, 3,3a, 3b ... External connection terminal connection part, 4, 4a, 4b ... Opening part, 9a ...... Wiring lead, 9b …… External terminal.

Front page continuation (72) Inventor Toshio Futami 3300, Hayano, Mobara, Chiba Prefecture Mobara Plant, Hitachi, Ltd. (72) Inventor, Tatsuo Hamamoto 3300, Hayano, Mobara City, Chiba Hitachi Ltd., Mobara Plant (56) Reference Literature JP-A-60-15888 (JP, A) JP-A-55-14506 (JP, A)

Claims (2)

[Claims] 1. A flexible wiring board having a chip mounting portion and an external connection terminal connecting portion mounted on the chip mounting portion,
Magnetic bubble memory chip electrically connected to this,
A magnetic bubble which is arranged at a position surrounded by a rectangular ring-shaped core having windings on two opposite sides, and which covers the magnetic bubble memory chip, the winding and the core with a rotating magnetic field confinement case. In a memory device, a magnetic bubble memory characterized in that the flexible wiring board formed in a substantially rectangular shape is configured such that a chip mounting portion and an external connection terminal connecting portion have substantially the same area and is bent at a boundary portion thereof. apparatus. 2. A pair of external connection terminal connection portions are provided on both sides of a chip mounting portion, and the pair of external connection terminal connection portions are bent at a boundary with the chip mounting portion. 2. A magnetic bubble memory device according to claim 1.