JP2003168942A - Manufacturing method of surface acoustic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a surface acoustic wave (SAW) device which is excellent in productivity and reliability. <P>SOLUTION: In an SAW device 100 which is sealed with a resin, a device chip 1 is connected to a base 3 electrically and mechanically through metal bumps 2 so that a hollow portion 7 including a comb teeth-like electrode 8 is formed between the chip 1 and the base 3. In a portion between the chip 1 and the base 3, a dam 20 is arranged at a position where a sealing resin 5 is prevented from entering the portion 7. This dam 20 cooperates with the bumps 2 in connecting the chip 3 to the base 3 structurally. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a surface acoustic wave device sealed with resin or the like. In particular, the present invention relates to a method of manufacturing a surface acoustic wave device suitable for a frequency filter of a mobile communication terminal.

[0002]

2. Description of the Related Art A surface acoustic wave device is a signal obtained by converting an electric signal and a surface acoustic wave (SAW) by a comb-shaped electrode (interdigital transducer: IDT) made of a thin film metal provided on a piezoelectric body. The device is a device for transmitting and receiving, and is used in a surface acoustic wave filter, a surface acoustic wave resonator, a delay circuit, and the like. This surface acoustic wave device has been widely used in recent years, particularly in the field of mobile communication such as a mobile phone, due to its merit that it can be made thin and compact.

Further, with the miniaturization of mobile phones, the demand for surface acoustic wave devices has become more and more severe. Front-end modules (FEM) that set radio frequency (RF) circuit components for mobile phones have also begun to appear in the world, and FE
SAW devices for M are required to be thinner than those for mobile phone makers.

Prior to the invention of the present application, the surface acoustic wave device was manufactured, for example, by the following method.
First, a surface acoustic wave element including an IDT and a terminal electrode is formed on a piezoelectric body with a metal thin film such as aluminum. Next, a dam that surrounds the surface acoustic wave element is formed with a photosensitive resin or the like (photolithography). Next, a metal bump is formed on the terminal electrode by bonding, and in this state, the element is separated into individual pieces by dicing or the like. Next, the surface acoustic wave element is joined to a base on which external connection terminals and element connection terminals are formed in advance by a method such as ultrasonic pressure bonding (flip chip bonding). Then, the surface of the surface acoustic wave device opposite to the device formation surface is integrally covered and fixed with a sealing resin or the like, so that the ID
The surface acoustic wave device containing T is sealed. After that, the sealed device is diced into individual pieces to be surface acoustic wave devices.

A known example using the flip-chip bonding (or face-down bonding) method is the "surface acoustic wave device" disclosed in, for example, Japanese Patent Laid-Open No. 11-74755.

[0006]

In the manufacturing method before the above-described invention of the present application, photolithography was performed for forming the dam, so that the number of manufacturing steps was large. In addition, the height of the dam must be lower than the height of the metal bumps and must be high enough to prevent the sealing resin from flowing in, which limits the height of the dam. Further, in order to surely prevent the inflow (entry / invasion) of the sealing resin, it is often necessary to use a sheet resin instead of a liquid resin having high fluidity as the sealing resin. And / or there was a constraint on the shape.

The present invention has been made in view of the above circumstances, and an object thereof is an elastic surface having high productivity (reducing the number of production steps) and high reliability (reliably preventing encapsulation resin from entering). A method of manufacturing a wave device is provided.

[0008]

According to the method of manufacturing a surface acoustic wave device according to the embodiment of the present invention, a piezoelectric body having a surface acoustic wave element, an external connection terminal and an element connection terminal are formed. The base is connected by flip chip bonding and dam agent. In the manufacture of this surface acoustic wave device, a dam is formed by a dispenser after individual surface acoustic wave elements are diced into individual pieces. At the same time as the flip chip bonding, the dam agent is hardened (according to the deformation change of the metal bump whose shape is changed by heat / pressing force during the flip chip bonding) to connect the base and the piezoelectric body. There is.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A surface acoustic wave device and a method of manufacturing the same according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the structure of a surface acoustic wave device 100 according to an embodiment of the present invention. In FIG. 1A, a surface acoustic wave element (device chip)
1 is a comb-shaped electrode (interdigital converter ID) made of a metal film such as aluminum or copper at a predetermined position on the piezoelectric body.
T) 8 and the terminal electrode 12 are formed. Further, element connection terminals 14 are formed at predetermined positions on the upper surface of the substrate (base) 3 made of ceramics or the like, and external connection terminals 16 are formed at predetermined positions on the lower surface. Each terminal 1
The terminals 4 are electrically connected to the corresponding terminals 16 through conductor via holes 18 penetrating predetermined positions of the base 3. Metal bumps 2 such as gold are attached to each of the electrodes 12 on the device chip 1.
Are configured to contact the corresponding electrodes 14.

The outer peripheral portion of the device chip 1 is shown in FIG.
As shown in (a) and (b), the dam 20 is arranged so as to surround the comb-shaped electrode 8 and the metal bump 2.
This dam 20 has an appropriate viscosity or thixot property.
ropy) thermosetting resin (epoxy, melamine,
It can be formed by applying a phenol-based or urea-based resin with a dispenser. Specifically, a two-component mixed epoxy resin in which the ratio of the main agent to the curing agent is about 1: 1 to 1: 3 can be used for the dam 20.

The dam 20 is not hardened just before the device chip 1 is flip-chip bonded to the base 3, and is in a relatively soft state (that is, it can be deformed according to the surrounding structural state). However, when the device chip 1 is flip-chip bonded to the base 3, the heat generated at that time cures the dam 20. that time,
The dam 20 before being hardened changes into a shape according to the crushed state of the metal bump 2 deformed by heat and pressure by flip chip bonding, and the device chip 1 and the base 3
By connecting and, almost completely set by the end of flip chip bonding (it may be completely set after that).

After the device chip 1 and the base 3 are electrically and mechanically (structurally) connected to each other via the metal bumps 2 and the dam 20 as described above, the inside of the dam 20 is shown in FIG. The hollow portion 7 as shown in (a) and (b) is formed. The hollow portion 7 around the comb-shaped electrode 8 is surrounded by a dam 20. A sealing resin 5 is applied by printing or the like from the outside of the device so as to cover the device chip 1. The sealing resin 5 is in a state of high fluidity (good wettability) at the time of application and easily enters the hollow portion 7 side without the dam 20. However, device chip 1
Since the dam 20 is in close contact with both the base 3 and the base 3, the sealing resin 5 is completely blocked by the dam 20,
It cannot enter the hollow portion 7 side where the comb-shaped electrode 8 is arranged.
From this, it is possible to eliminate the risk of product defects due to foreign matter (sealing resin 5) adhering to the electrodes 8.

In other words, the features of the embodiment shown in FIG. 1 are as follows. That is, between the device chip (surface acoustic wave element) 1 and the base (substrate) 3,
A dam 20 arranged at a position to prevent the sealing resin (sealing material) 5 from entering the hollow portion (space portion) 7 cooperates with the metal bump 2 to structurally connect the device chip 1 and the base 3 to each other. It is configured to connect (mechanically). With such a configuration, the mechanical connection strength between the device chip 1 and the base 3 can be increased as compared with the case where the device chip 1 and the base 3 are connected only by the bump 2. That is, the dam 20 has a function of reinforcing the mechanical connection via the bump 2 in addition to the original function of preventing resin from entering.

The important thing to obtain this reinforcing function is
Between the device chip 1 and the base 3, (a) the dam 20 must not be cured first at the height of the bump 2 or higher during the flip chip bonding (if the dam 20 is cured first, it depends on the bump 2). The connection between the electrode 12 and the terminal 14 may be incomplete, and even if this connection is perfect, the hard dam 20 is sandwiched between them, so that mechanical strain remains in the device chip 1 and the elastic surface (B) The characteristics of the wave element may change); (b) During flip chip bonding, the dam 20 is deformed and hardened according to the shape change of the bump 2, and the hardened dam 20 is hardened. (If it is not adhered, it does not reinforce the mechanical connection strength, and if there is a large gap in the part that does not adhere, it also prevents the encapsulation resin from entering. There is a risk of rope).

FIG. 2 is a diagram illustrating a method of manufacturing the surface acoustic wave device 100 according to the embodiment of the present invention. Here, a method for efficiently mass-producing the device 100 having the structure of FIG. 1 will be described.

First, for example, the device 1 of several 10 × 10
A piezoelectric wafer (piezoelectric substrate) 1a having a size in which 00s are formed vertically and horizontally is prepared (FIG. 2a). For this wafer 1a, for example, lithium tetraborate or lithium tantalate can be used.

On the wafer 1a, comb-shaped electrodes (ID
The surface acoustic wave element (device chip) 1 including T) 8 and the terminal electrode 12 is formed (FIG. 2b). Thin films of aluminum alloy or copper alloy, for example, can be used for these electrodes 8 and 12.

Next, the terminal electrode 12 of each device chip 1
The metal bumps 2 are attached to the top by bonding or the like (FIG. 2c). For this bump 2, for example, gold or a gold alloy can be used.

Each device chip 1 having the bumps 2 attached to the terminal electrodes 12 in this manner is subjected to dicing or the like.
At the broken line position in Figure 2c, it is cut into pieces (Figure 2d). For this dicing, for example, a diamond cutter can be used.

Next, a dam 20 as shown in FIGS. 1A and 1B is formed at a predetermined position on the individualized device chip 1 (FIG. 2E). This dam formation can be performed, for example, by applying an epoxy thermosetting resin so that the thickness thereof is slightly higher than the height of the metal bumps 20.

As a specific example, assuming that the thickness of the electrode 12 + the height of the bump 20 is controlled to about 40 μm to 60 μm before the flip chip bonding, the resin for the dam 20 applied by a dispenser is The thickness may be controlled to, for example, about 70 μm to 140 μm (or more).

Each device chip 1 on which the metal bumps 20 and the dams 20 are formed in this manner is a flat plate on which the element connection terminals 14 and the external connection terminals 16 electrically connected to the terminals 14 via the via holes 18 are formed in advance. Face-down mounted on the base 3 (see FIGS. 2e to 2).
f). The base 2 can be made of ceramics such as alumina.

Metal bumps 2 and dams 20 (before curing)
Base 3 to which a plurality of device chips 1 are abutted via
Is subjected to ultrasonic vibration for a predetermined time under predetermined heating / pressurization by an ultrasonic bonding device (not shown) to perform flip chip bonding (FIG. 2f).

By this flip chip bonding,
Metal bump 2 and electrode 12 and metal bump 2 and terminal 14
The contact surface with is partially melted and welding is performed. At that time, the metal bump 2 is deformed into a somewhat crushed shape. At that time, the dam 20 is still in a state before curing, and the dam 20 is
The bump 2 is easily thinned in accordance with the deformation of the bump 2 and adheres to both the device chip 1 and the base 3. Dam 20
Starts to be hardened immediately by the heat applied at the time of flip chip bonding, and at the end of the flip chip bonding, it is almost solidified with a thickness according to the deformation of the bump 2 (it is not completely solidified immediately after the completion of the flip chip bonding. Also, it should be solid enough to function as a dam by the next step).

Next, from the top of the base 3 to which a large number of device chips 1 are attached by flip chip bonding (from the side opposite to the surface on which the electrodes 8 are formed when viewed from the individual device chips 1 side), a predetermined viscosity and / Alternatively, the sealing resin 5 having a predetermined thixotropy is applied by a technique such as printing (FIG. 2g). At this stage, dam 2 of each device chip 1
0 is solidified and is now fully functional as a dam. Therefore, there is no possibility that the sealing resin 5 will enter the internal space (hollow portion 7) of each device chip 1. Therefore, as the sealing resin 5, a liquid resin having high fluidity (having good wettability) can be used. However, the sealing resin 5 need not be limited to the liquid resin, and a sheet-shaped resin may be used as the sealing resin 5.

After the encapsulating resin 5 is completely solidified, each device chip 1 together with the encapsulating resin 5 and the base 3 is shown in FIG.
Each surface acoustic wave device 100 is completed by cutting into individual pieces at the position indicated by the broken line (FIG. 2h). For this dicing,
For example, a diamond cutter can be used.

FIG. 3 is a diagram for explaining the structure of a surface acoustic wave device according to another embodiment of the present invention. In the configuration of FIG. 3, the dam 20 is arranged at a position that surrounds the comb-shaped electrode 8 inside the arrangement of the metal bumps 2. Even if the sealing resin 5 comes into contact with the metal bumps 2, no particular abnormality occurs in the surface acoustic wave device. Therefore, FIG. 3 is shown as an example of the case where the bumps 2 may be outside the dam 20.

In the structure shown in FIG. 3, the bumps 2 are arranged and
When the dimensions are the same as in the configuration of FIG. 1, the hollow portion 7 between the dam and the electrode 8 becomes narrower than in the case of FIG. If the hollow portion 7 becomes narrower, there is a possibility that part of the dam agent will stick to the electrode 8 during the manufacturing process of the device 100. In such a case, the configuration of FIG. 1 may be adopted instead of the configuration of FIG.

The present invention is not limited to the above-mentioned embodiments, and various modifications and changes can be made at the stage of carrying out the invention without departing from the spirit of the invention. Also,
The respective embodiments may be combined as appropriate as much as possible, and in that case, the effect of the combination can be obtained.

Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of constituent elements disclosed in this application. For example, even if one or more constituent elements are deleted from all the constituent elements shown in the embodiment, if at least one of the effect of the present invention or the effect of implementing the present invention is obtained, the constituent element is The deleted configuration can be extracted as an invention.

<Effects of the Embodiment> By forming the dam 20 with a dispenser and simultaneously curing the dam agent and flip-chip bonding, the number of production steps can be reduced and the productivity of the surface acoustic wave device can be improved. You can

Further, since the dam 20 is structurally connected to both the device chip 1 and the base 3, the sealing resin 5 is blocked by the dam 20 during resin sealing, and the comb-teeth-shaped electrode is formed. There is no inflow (entry or intrusion) to a position of 8. As a result, there is no risk of foreign matter (sealing resin) adhering to the electrode 8 and the reliability of the product is improved. Further, there are almost no restrictions on the material and / or the shape of the sealing resin 5 (a liquid resin or a sheet resin can be used as the sealing resin 5).

Further, the device chip 1 and the base 3
The dam 20 structurally connected to both of them is cured after the flip chip bonding process to become a relatively strong structure. Therefore, regarding the mechanical connection strength between the device chip 1 and the base 3, the hardened dam 20 acts to further strengthen the connection strength by the metal bumps 2. That is, the dam 20 arranged at a position where the encapsulation resin 5 is prevented from entering cooperates with the metal bump 2 to firmly connect the device chip 1 and the base 3 structurally (mechanically).

Further, the dam agent before curing can be easily deformed in accordance with the deformation of the bumps 2 during flip chip bonding, and the dam agent is cured thereafter, so that the dam 20 is used.
Due to the presence of the device chip (surface acoustic wave element) 1
No mechanical strain (stress strain inside the piezoelectric body) is applied to the.

[0036]

EFFECTS OF THE INVENTION There are few restrictions on the material and / or shape of the encapsulating resin, and it is possible to obtain a method of manufacturing a surface acoustic wave device having high productivity and high reliability.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a structure of a surface acoustic wave device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of manufacturing a surface acoustic wave device (mass production method) according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating the structure of a surface acoustic wave device according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Device chip (surface acoustic wave element); 1a ... Piezoelectric wafer; 2 ... Metal bump (conductive bump); 3 ... Base (substrate); 5 ... Sealing resin (sealing material); 7 ... Hollow part ( Space part; 8 ... Comb-shaped electrode (interdigital converter ID
T); 12 ... Terminal electrode; 14 ... Element connection terminal; 16 ... External connection terminal; 18 ... Via hole; 20 ... Dam (dam agent); 100 ... Surface acoustic wave device.

Claims (4)

[Claims] 1. A step of producing a plurality of surface acoustic wave elements each having a comb-shaped electrode and a terminal electrode formed on a piezoelectric body, and a predetermined step of contacting the terminal electrodes of each of the plurality of produced surface acoustic wave elements. Attaching a metal bump to the position, forming a dam agent made of a thermosetting resin with a dispenser at a predetermined position avoiding the formation position of the comb tooth-shaped electrode and the attachment position of the metal bump, and an element at a predetermined position. Mounting a plurality of the surface acoustic wave devices on a base having connection terminals and external connection terminals so that the attached metal bumps come into contact with the device connection terminals; and under a predetermined temperature and pressure. By applying ultrasonic waves, the metal bumps are partially melted, and the terminal electrodes and the element connection terminals are electrically and mechanically connected via the metal bumps. Flip chip bonding step of connecting, and sealing after the flip chip bonding step is completed, integrally encapsulating the plurality of surface acoustic wave elements with a sealing material from the side opposite to the surface on which the comb-shaped electrodes are formed. A method of manufacturing a surface acoustic wave device, comprising: a step; and, after the sealing step, a step of dividing a portion including each of the plurality of surface acoustic wave elements into individual pieces. 2. The method of claim 1, wherein the dam agent is configured to cure in the flip chip bonding process. 3. The dam agent is in a non-hardened state before the flip chip bonding step, and the dam agent is hardened in a shape according to the shape change of the conductive bump during the flip chip bonding step. The method according to claim 1 or 2, wherein the method is configured as follows. 4. The dam agent according to claim 1, wherein the dam agent is an epoxy-based, melamine-based, phenol-based, or urea-based thermosetting resin. The method described in.