JP2000124767A - Substrate mounting method for saw filter chip and saw filter chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the substrate mounting method of a SAW filter chip for increasing a substrate mounting density at a low cost. SOLUTION: In this substrate mounting method, sealing walls 8 and 10 are formed on this SAW filter chip 1, and the sealing walls 8 and 10 are tightly adhered to the conductor pattern 22 of a substrate 20. As a result, a space on a chip surface 24 where a SAW filter is formed is turned to a tightly sealed space by the SAW filter chip 1, the sealing wall 10 and the substrate 20, and the SAW filter chip 1 is mounted to the substrate 20 with its face down. At the mounting of the substrate, since an area occupied by the SAW filter chip 1 can be about the size of the chip, the substrate mounting density is enhanced. Also, since the SAW filter chip 1, the sealing wall 10 and the substrate 20 are used as a sealing body, the number of components and, the number of manufacture processes are reduced as well and a manufacture cost can be suppressed to be low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for mounting a SAW filter chip on a substrate and a SAW filter chip.

[0002]

2. Description of the Related Art A SAW filter chip has a SAW filter surface.
(Surface acoustic wave) filters are formed and widely used in electronic communication devices and the like. The SAW filter chip is usually sealed in a sealing body or the like and mounted on a substrate. Since the SAW filter obtains electric characteristics by the surface acoustic wave propagating between the comb-shaped electrodes formed on the surface of the SAW filter chip, when the SAW filter chip is sealed, at least the surface of the SAW filter is formed on the surface on which the SAW filter is formed. Needs space. Further, when dust, moisture, or the like adheres to the comb-shaped electrodes, the characteristics of the SAW filter change due to a change in the propagation characteristics of the surface acoustic wave propagating between the comb-shaped electrodes. Therefore, it is desirable that the space on the surface on which the SAW filter is formed is a closed space.

FIG. 4 shows a conventional method of enclosing a SAW filter chip and a method of mounting the same on a substrate. In FIG. 4A, the SAW filter chip 1 is sealed in a sealing body 40. Then, the lower electrode 42 drawn out of the sealing body 40 is connected to the conductor pattern 2 on the substrate 20.
The sealing body 40 in which the SAW filter chip 1 is sealed is mounted on the substrate 20 by being connected to the solder 2 with the solder 43.
The sealing body 40 includes a cavity 46 made of ceramic or the like, and a lid 48 made of metal or plastic. First, the back surface of the chip is attached to the bottom surface 50 of the cavity portion 46 with an adhesive or the like without the lid portion 48. Then, the electrode 4 on the SAW filter chip 1 and the lower electrode 42 are connected by a thin metal wire 54. Thereafter, the lid portion 48 is electrically welded onto the cavity portion 46. In this manner, the SAW filter chip 1 is mounted “face-up” on the substrate 20 with the surface 24 on which the SAW filter is formed facing upward.

FIG. 4B shows a method for encapsulating a SAW filter chip using bumps for connecting the lower electrode 42 and the electrode 4 and a method for mounting the substrate. First, S
A bump 6 made of Au or the like is formed on the electrode 4 of the AW filter chip 1. And the SAW filter chip 1
Of the cavity 24 of the sealing body 40
0, and the bump 6 and the lower electrode 42 are welded by ultrasonic welding or the like, and the SAW filter chip 1 is
6 and the electrode 4 and the lower electrode 42 are connected. Thereafter, the lid portion 48 is electrically welded onto the cavity portion 46. Thus, the SAW filter chip 1
Is mounted on the substrate 20 "face down" with the surface 24 on which the SAW filter is formed facing down.

FIG. 4 (c) shows that the resin coat has a SA.
A method of enclosing the W filter chip 1 and mounting it on a substrate is shown. First, the back surface of the SAW filter chip 1 is attached to the lead frame 62 with an adhesive or the like, and the SAW filter chip 1 is fixed to the lead frame. After that, the electrode 4 on the SAW filter chip 1 and the lead frame 62 are connected by the thin metal wire 54. Then, the SAW filter chip 1 is sealed with a resin or the like while keeping a space on the surface 24 together with a part of the lead frame. Thereafter, the electrode 4 is connected to the conductor pattern 22 by connecting the conductor pattern 22 on the substrate 20 and the lead frame 62 with solder 64.

As described above, conventionally, the entire SAW filter chip is sealed in a sealing body made of ceramic or the like, and then the sealing body is mounted on a substrate.

[0007]

However, in the conventional method, since the entire SAW filter chip is covered by the sealing body, the size of the sealing body becomes large, and the mounting density when mounted on a substrate becomes low. There was a problem.

Further, in the conventional method, there is a step of mounting the SAW filter chip on a substrate after the step of enclosing the SAW filter chip in a sealing body, and there is a problem that the number of steps is large and the manufacturing cost is high. In particular, in the substrate mounting method shown in FIGS. 4A and 4B, the lid portion 4
Since a process of welding 8 is required, the manufacturing cost is further increased. 4A and FIG.
The board mounting method shown in (b) has a problem that the number of components is large and the component cost is high.

The present invention has been made in view of the above problems, and has as its object to provide a method of mounting a SAW filter chip on a substrate at a high density and at a low cost.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a method for mounting a SAW filter chip on a substrate, wherein the SAW filter chip has a SAW filter chip formed on one main surface. A stop wall is formed, the sealing wall is brought into close contact with the substrate, and the SAW filter chip is mounted face-down on the substrate.

Further, the SAW filter chip of the present invention comprises:
The SAW filter is a SAW filter chip formed on one main surface, and has a sealing wall surrounding the SAW filter on the main surface.

As described above, in the present invention, the sealing wall formed on the SAW filter chip is brought into close contact with the substrate, so that the sealing wall, the substrate, and the SAW filter chip form an SW filter chip.
A closed space is formed on the AW filter, and at the same time, a SAW filter chip is mounted on a substrate. Since the size of the sealing wall can be as large as the size of the SAW filter chip, the mounting density on the substrate can be increased. Also, SAW
Since a sealed space is formed on the filter, that is, the SAW filter is sealed and mounted on the substrate at the same time, the number of manufacturing steps can be reduced. Also, the substrate and S
Since the AW filter chip itself is used as a sealing component, the number of components can be reduced.

The present invention also provides a sealing wall having a shape surrounding a SAW filter formed on one main surface of a SAW filter chip on a substrate, and the sealing wall is formed on a main surface of the SAW filter chip. The SAW filter chip is mounted face down on the substrate.

Thus, by forming the sealing wall on the substrate and bringing the sealing wall into close contact with the SAW filter chip, a closed space is formed on the SAW filter by the sealing wall, the substrate and the SAW filter chip. At the same time, the SAW filter chip may be mounted on the substrate.

In the above-mentioned substrate mounting method, the SAW
The filter chip and the substrate may be connected by bumps.

The present invention also relates to a method of mounting a SAW filter chip on a substrate, wherein the SAW filter chip has a SAW filter formed on one main surface thereof.
A sealing wall surrounding the W filter is formed, the sealing wall is brought into close contact with an inner surface of a sealing body covering the SAW filter chip, the SAW filter chip is sealed in the sealing body, and the sealing body is mounted on a substrate. Is implemented.

As described above, according to the present invention, even when the SAW filter chip is sealed in the sealed body, the lid portion is not required as compared with the conventionally used sealed body.
It is possible to reduce the number of parts.

In the substrate mounting method, the SAW
The filter chip and the sealing body may be connected by a bump.

[0019]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1A is a plan view of a SAW filter chip having a sealing wall formed on a surface according to the present embodiment.
FIG. 1B shows a side view thereof. On the SAW filter chip 1, a comb-shaped electrode 2 is formed. A metal wire is led out from the comb-shaped electrode 2, and an electrode 4 is formed at the tip thereof. Au having a height of about 100 μm is formed on the electrode 4.
Are formed. The SAW filter of this embodiment inputs a signal to the electrode 4 and
Electrical characteristics are obtained by surface acoustic waves propagating between them.

On the SAW filter chip 1, sealing walls 8 and 10 are formed. The sealing walls 8 and 10 are formed by applying an ultraviolet curable resin to the entire surface of the SAW filter chip 1 with a thickness of about 50 μm, and then using photolithography technology to form a shape surrounding the comb electrode 2. This is because a closed space is formed on the comb-shaped electrode 2, that is, on the SAW filter in a process described later. In addition, the sealing wall 8
And 10 may be formed of silicon resin applied on the SAW filter chip 1 so as to surround the comb electrode 2 with a dispenser or the like.

It is desirable that the height h of the bump is larger than the thickness t of the sealing walls 8 and 10, as shown in FIG. This is a step which will be described later.
If the height is lower than the sealing walls 8 and 10, the bumps cannot be ultrasonically welded to the conductor pattern 22 on the substrate 20.

After the sealing walls 8 and 10 are formed on the SAW filter chip 1, the bumps 6 are ultrasonically welded to the conductor pattern 22 on the substrate 20, and the sealing walls 8 and 10 are brought into close contact with the conductor pattern 22. Can be As a result, as shown in FIG. 2, a closed space is formed on the comb-shaped electrode 2, that is, on the SAW filter by the substrate 20, the sealing wall 10, and the SAW filter chip 1, and at the same time, the SAW filter chip 1 The chip is mounted on the substrate 20 face down with the surface 24 of the chip facing down.

As described above, in the present embodiment, a closed space is formed on the SAW filter by the substrate 20, the sealing wall 10, and the SAW filter chip 1, and at the same time, the SAW filter chip 1 is mounted on the substrate 20. . Therefore, as compared with the conventional method of mounting after sealing, the number of manufacturing steps can be reduced and the manufacturing cost can be reduced.

Further, since a closed space is formed by the substrate 20, the sealing wall 10, and the SAW filter chip 1, the parts of the sealing body which have been conventionally required, that is, FIGS. 4 (a), (b),
The cavity 26 and the lid 4 of the sealing body 40 shown in FIG.
8, and the sealing body 66 becomes unnecessary. Therefore, the number of components can be reduced, and the cost of components can be reduced.

Since the sealing walls 8 and 10 may have a size that surrounds the comb-shaped electrode 2, they may be as large as the SAW filter chip 1. Therefore, the conventional SA
Compared with the method of enclosing the entire W filter chip with a sealing body, it is possible to increase the mounting density on the substrate.

In this embodiment, the sealing walls 8 and 10
Is sealed to the conductor pattern 22 on the substrate 20, but the sealing walls 8 and 10 may be adhered to a portion of the substrate 20 where there is no conductor pattern. In this case, the height h of the bump and the thickness t of the sealing wall must be appropriately selected so that the bump can be bonded onto the conductive pattern 22.

Further, the sealing wall is only required to form a closed space together with the substrate 20 and the SAW filter chip 1.
Only one of the sealing wall 8 and the sealing wall 10 may be used.

In the present embodiment, the sealing wall is formed on the SAW filter chip 1. However, the sealing wall may be formed on the substrate 20, and the sealing wall may be adhered to the SAW filter chip 1.

Further, as shown in FIG. 3, the bump 6 is joined to a lead electrode 32 formed on the inner wall of the sealing body 30,
By joining the lead electrode 32 and the conductor pattern 22 on the substrate 20 with solder 36, the SAW filter chip 1
May be mounted on the substrate 20 face up. At this time, the bump 6 and the extraction electrode 32 are connected by ultrasonic welding. In this mounting method, FIGS. 4A and 4B
As compared with the above, the lid portion 48 becomes unnecessary, and it is possible to reduce the number of parts and the cost of parts.

[0031]

As described above, in the present invention, a sealed space is formed on a SAW filter by a sealing wall, a substrate, and a SAW filter chip, and at the same time, the SAW filter chip is mounted on the substrate. Therefore, when mounting on a board, SAW
The occupied area of the filter chip is reduced, and the mounting density can be increased. Also, since the number of parts is reduced, the cost of parts can be reduced, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a SAW filter chip according to an embodiment.

FIG. 2 is a diagram illustrating a method for mounting a SAW filter chip on a substrate according to the embodiment;

FIG. 3 is a diagram illustrating a method for mounting a SAW filter chip on a substrate according to another embodiment.

FIG. 4 is a view showing a conventional SAW filter chip substrate mounting method.

[Explanation of symbols]

2 comb electrodes, 4 electrodes, 6 bumps, 8, 10 sealing walls, 20 substrates, 22 conductor patterns, 24 chip surfaces, 30, 40, 66 sealing bodies, 32 extraction electrodes,
36, 43, 64 Solder, 42 Lower electrode, 46 Cavity, 48 Lid, 54 Fine metal wire, 62 Lead frame.

Claims (6)

[Claims] 1. An SW filter having a SAW filter formed on one main surface.
A sealing wall surrounding the SAW filter is formed on the main surface of the AW filter chip, the sealing wall is brought into close contact with the substrate, and the SAW filter chip is mounted face down on the substrate. A method for mounting a SAW filter chip on a substrate. 2. An SW filter having a SAW filter formed on one main surface.
An AW filter chip, comprising: a sealing wall surrounding the SAW filter on the main surface. 3. A sealing wall having a shape surrounding the SAW filter formed on one main surface of the SAW filter chip is formed on the substrate, and the sealing wall is brought into close contact with the main surface of the SAW filter chip, A method of mounting a SAW filter chip on a substrate, wherein the SAW filter chip is mounted face down on the substrate. 4. The method for mounting a SAW filter chip on a substrate according to claim 1, wherein the SAW filter chip and the substrate are connected by bumps. Method. 5. An SW filter having a SAW filter formed on one main surface.
A sealing wall surrounding the SAW filter is formed on the main surface of the AW filter chip, and the sealing wall is brought into close contact with an inner surface of a sealing body covering the SAW filter chip, thereby sealing the SAW filter chip. A method for mounting a SAW filter chip on a substrate, wherein the method is enclosed in a body and the sealing body is mounted on a substrate. 6. The method for mounting a SAW filter chip on a substrate according to claim 5, wherein the SAW filter chip and the sealing body are connected by bumps.