JPS622390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a mounting structure of a magnetic bubble memory device suitable for mass production.

(b) Background of the technology In magnetic bubble memory devices (hereinafter referred to as bubble memory devices), permanent magnets are used to constantly apply a bias magnetic field of uniform strength to magnetic bubble memory chips (hereinafter referred to as chips). In order to propagate magnetic bubbles (hereinafter referred to as bubbles) along the transfer pattern, a configuration method is used in which a rotating magnetic field is applied horizontally to the chip. In order to generate the rotating magnetic field, a method is used in which a pair of orthogonal coils is used and a sine wave current or triangular wave current is passed through the coil drive circuit with a phase shift of 90 degrees. There are two methods of coil structure: one in which two solenoids are orthogonal to each other, and the other in which two planar coils are orthogonal to each other.The former structure is usually used. That is, the solenoid has good magnetic field area efficiency (effective rotating magnetic field area/coil size) and magnetic field current efficiency (rotating magnetic field strength per unit current). However, since the chip position is surrounded by coil walls on all sides, it is inconvenient to insert and remove the chip, and to draw out the lead wires.Usually, the chip is fixed in the center of the magnetic board and a notch in the board is used to connect the X coil and Although the Y coil is inserted and fixed, it is virtually impossible to replace the tip after the coil is installed. On the other hand, the latter has a structure in which planar coils orthogonal to each other are arranged parallel to a conductive substrate such as a copper plate, and when arranged in this way, a rotating magnetic field can be created on the surface of the conductive plate by an image effect. The characteristics of this structure are that the chip is located on the surface of the conductor plate and is open on all sides, making it easy to design and assemble, and because printed wiring technology is used to make the coil, mass production is easy. . The present invention relates to the structure of a bubble memory device using a planar coil.

(c) Prior art and problems The inventor has already proposed a bubble memory device using a planar coil (IEEE Transactions on
Magnetics, Vol.Mag―11, no.5 Sept.1975). FIG. 1 is a conventional cross-sectional structure showing this configuration, and FIG. 2 is a perspective view thereof. That is, a plurality of chips 1 (four in this case) are mounted on a conductive substrate 2 whose surface is insulated, and are provided around the conductive substrate 2 through printed wiring formed on this insulating film. The circuit connection is made to the terminal section where the terminal is located.
For example, a copper plate is used as the conductor substrate 2, silicon dioxide (SiO ₂ ) is vapor-deposited on the surface, or polyimide is coated to insulate the plate, and printed wiring is applied to this plate, and chips are bonded to the plate and interconnected by bonding. Wiring connections to the chip are made by doing this. Next, on the conductor substrate 2, planar coils consisting of an X coil 3 and a Y coil 4 are provided orthogonally. Here, the conductive substrate 2 produces an image effect on these planar coils, and also contributes to heat radiation. That is, it acts like a short-circuited secondary coil and reduces the effective coil inductance. Next, permanent magnets 5, which apply a bias magnetic field to the chip 1, are installed on both sides of a yoke 6 made of an iron plate, etc., and a perpendicular magnetic field is applied to the chip 1 by means of ferrite plates 7, which are provided to increase the magnetic field efficiency. There is. Bubble memory devices using such planar coils are suitable for use at high frequencies and have the advantage of reducing chip temperature rise and generating less induction noise. The bubble memory device having the structure shown cannot be said to be suitable for mass production.

(d) Object of the invention The object of the invention is to provide a structure of a bubble memory device using a planar coil and suitable for mass production.

(e) Structure of the Invention An object of the present invention is to have a window opening for accommodating a magnetic bubble memory chip in the center of the board, and to lead printed wiring from the window opening to lead terminals on the outer periphery of the board. a non-magnetic metal conductor plate fixed to the back surface of the insulating substrate such that the memory chip is adhesively fixed to the center of the upper surface side and the memory chip is located within the window opening; and the insulating substrate a planar coil and a magnetic shunt plate that are stacked and housed in a recess formed on the outer surface of the conductor plate; a permanent magnet and a magnetic shunt plate that are laminated and housed in a recess formed on the outer surface of the conductor plate; The planar coil, the magnetic shunt plate, the permanent magnet, and the magnetic shunt plate are provided in respective recesses of the insulated substrate and the conductive plate, and at least a shield case is provided to cover the surroundings thereof. This can be achieved with a magnetic bubble memory device.

(f) Embodiments of the Invention Fig. 3 is a sectional view of the mounting structure of the magnetic bubble memory device according to the present invention, Fig. 4 is a perspective view showing the external appearance of the product, and Fig. 5 A to G are assembly steps of the memory device. FIG. 2 is a perspective view of components for explaining. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to specific implementation forms will be described below with reference to the drawings. The ceramic substrate 9, which has a plurality of lead terminals 8 on both sides in order to adopt a dual-in-line structure, has a square hole 10 in the center, and bonding pads are provided in the stepped portion 11 around the square hole 10, allowing multilayer wiring to be formed. Each bonding pad and lead terminal 8 are connected to each other in a circuit. Further, the upper surface of the ceramic substrate 9 has a recess 12 with a step around the periphery.
A plurality of thin plates (planar coils and copper plates to be described later) are positioned and mounted inside this recess (FIG. 5A). Next, under the ceramic substrate 9 is a conductor plate 13 made of an aluminum die-cast with the same area as this, and on the upper surface of this conductor plate 13 is a copper (Cu) plating 14 for producing the image effect of a planar coil. is applied to a thickness of 50 to 100 [μm] (Fig. 5B). Furthermore, there is a recess 15 with a certain inclination angle on the lower surface of the conductor plate 13, into which a magnetic field shunt plate 16 and a permanent magnet 17 are inserted (FIG. 5C).
That is, the recess 15 on the lower surface of the conductive plate 13 is die-cast with an inclination of several degrees in the direction of applying the hold magnetic field in order to apply a hold magnetic field to the chip.
The ceramic substrate 9 and the conductor plate 13 are then brought into close contact with each other and sealed by heat using solder paste or the like. Next, the conductor plate 1 is inserted through the square hole 10 of the ceramic substrate 9.
A chip 19 is die-bonded to the copper plating 14 surface on top of the chip 3, and wire-bonded to a bonding pad provided on the stepped portion 11. FIG. 5D shows this state. In this embodiment, four chips 19 are installed, and after the chips 19 are installed, the upper part of the square hole 10 is welded with a sealing material 20 such as a ceramic sealer. By sealing, the chip 19 is hermetically sealed. Next, planar coils constituting the erasing coil 21, the Thickness with square hole 24 0.5
A copper plate 25 of ~1 mm is inserted, and a ferrite plate 26 of the same thickness is fitted into the square hole 24 (FIGS. 5F and G). Here, the copper plate 25 is the planar coil 21
This is to short-circuit the magnetic flux in the unnecessary parts of the coils 21 to 24 to lower the coil inductance, and the ferrite plate 26 also acts as a flux keeper for the planar coils 21 to 23 to prevent external leakage of alternating current magnetic flux and reduce the load on the coils due to eddy currents. This has the effect of reducing the bias magnetic field as well as efficiently applying a bias magnetic field. Next, after being integrated around the ceramic substrate 9 in this way, the bubble memory device is completed by storing it in the shield case 27. FIG. 4 is a perspective view of the completed body stored in a shield case 27 and magnetically shielded.

(g) Effects of the Invention By adopting the mounting form according to the present invention, it becomes possible to mass-produce magnetic bubble memory devices that use planar coils as drive coils.

[Brief explanation of the drawing]

Figures 1 and 2 show the conventional structure of a magnetic bubble memory device using a planar coil; Figure 1 is a front sectional view;
Fig. 2 is a perspective view, Figs. 3 to 5 show the structure according to the present invention, Fig. 3 is a front sectional view, Fig. 4 is a perspective view showing the completed body, and Figs. 5 A to G are configurations. FIG. In the figure, 1 and 19 are chips, 3 and 22 are X
Coils, 4 and 23 are Y coils, 5 and 17 are permanent magnets, 13 is a conductive plate, and 14 is copper plating.

Claims (1)

[Scope of Claims] 1. An insulating substrate that has a window opening for accommodating a magnetic bubble memory chip in the center of the substrate, and from which printed wiring is led out to lead terminals on the outer periphery of the substrate; a non-magnetic metal conductor plate fixed to the back surface of the insulating substrate so that the memory chip is adhesively fixed to the center of the upper surface side and the memory chip is located in the window opening; and a non-magnetic metal conductor plate formed on the outer surface of the insulating substrate. a planar coil and a magnetic shunt plate that are stacked and housed in a recess formed on the outer surface of the conductor plate; a permanent magnet and a magnetic shunt plate that are laminated and housed in a recess formed on the outer surface of the conductor plate; and the fixed insulating substrate. A magnetic bubble memory device comprising at least a shield case that covers the planar coil, the magnetic shunt plate, the permanent magnet, and the magnetic shunt plate provided in each recess of the conductive plate.