JPH04293310A - Surface acoustic wave device - Google Patents

Abstract

PURPOSE:To reduce the number of components and to decrease the man-hours required for the assembling by using a surface acoustic wave element chip itself as a part of a packaging member. CONSTITUTION:A solder sealing frame 43 is used to mechanically couple a surface acoustic wave element chip 22 with a base plate 33 and connects electrically an earth side pattern 28 and an earth side land 34. A solder bump 44 connects electrically a hot side pattern 31 and a hot side land 35 a solder bump 45 connects electrically a hot side pattern 32 and a hot side land 36 respectively. Then the surface acoustic wave element 22 itself gives an air-tight sealed packaging structure together with a base plate 33 and a solder sealing frame 43 and the thickness of the solder sealing frame 43 and the solder bumps 44, 45 are used to form a space required for propagating the surface acoustic wave.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device, and more particularly to a packaging structure for a surface acoustic wave device that can be surface mounted.

0002

2. Description of the Related Art FIG. 7 shows a sectional view of a conventional surface acoustic wave device 1 that is airtightly packaged and can be surface mounted.

The packaging member of the surface acoustic wave device 1 is composed of a multilayer substrate 2 and a metal plate 3. The multilayer substrate 2 is made of, for example, alumina, and a ground side external electrode 4 and a hot side external electrode 5 are formed on the outer surface of the end portion thereof. Further, inside the multilayer substrate 2, ground side conductive layers 6 and 7 are formed so as to be electrically connected to the ground side external electrode 4, and a hot side external electrode 5 is formed.
A hot side conductive layer 8 is formed so as to be electrically connected to. The metal plate 3 is welded to the upper surface of the multilayer substrate 2 over the entire circumference via a Kovar ring 9. In this way, a highly airtight space is formed between the multilayer substrate 2 and the metal plate 3.

A recess 10 is formed in the multilayer substrate 2, and a surface acoustic wave element chip 11 is disposed within the recess 10. The surface acoustic wave element chip 11 is fixed by being die-bonded onto the ground side conductive layer 7, and is electrically connected to the ground side conductive layer 6 and the hot side conductive layer 8 by bonding wires 12 and 13, respectively. be done.

In this way, the formation of the space necessary for the propagation of surface acoustic waves and high airtightness are achieved between the multilayer substrate 2 and the metal plate 3.
provided by a packaging member consisting of; and
The necessary electrical connections are made by bonding wires 12 and 13.
given by.

[0006]

However, the surface acoustic wave device 1 shown in FIG. 7 requires three parts, the multilayer substrate 2, the metal plate 3, and the Kovar ring 9, for packaging. The cost of the multilayer substrate 2 itself is relatively high, and furthermore, welding is required to join the metal plate 3 to the multilayer substrate 2, so the cost for packaging is high. Furthermore, in assembling the surface acoustic wave device 1, at least three steps are performed: die bonding of the surface acoustic wave element chip 11, wire bonding using bonding wires 12 and 13, and welding of the metal plate 3.
Two steps are required. Therefore, there is also the problem that the assembly process is relatively complicated.

[0007] Therefore, an object of the present invention is to provide a surface acoustic wave device that can solve these problems.

[0008]

[Means for Solving the Problems] A surface acoustic wave device according to the present invention first includes a surface acoustic wave element chip. This surface acoustic wave element chip includes a substrate, an interdigital transducer formed on the substrate, and a ground line connected to the ground side line of the interdigital transducer and formed on the substrate so as to surround the interdigital transducer. and a hot side pattern connected to a hot side line of the interdigital transducer.

[0009] A base plate is disposed opposite to the surface of the substrate on which the interdigital transducer of such a surface acoustic wave element chip is formed. This base plate includes a ground side land formed at a position corresponding to the ground side pattern, a hot side land formed at a position corresponding to the hot side pattern, and a ground side electrically connected to the ground side land. The hot side external electrode is electrically connected to the hot side land.

[0010] Furthermore, the ground side pattern and the ground side land are connected by a solder sealing frame.

Furthermore, the hot side pattern and the hot side land are connected by a solder bump.

0012

[Function] In this invention, the solder sealing frame mechanically joins the surface acoustic wave element chip and the base plate, and
It functions to electrically connect the ground side pattern and the ground side land. Further, the solder bump functions to electrically connect the hot side pattern and the hot side land. Furthermore, the surface acoustic wave device chip itself, together with the base plate and the solder sealing frame, provides a hermetically sealed packaging structure, and the thickness of the solder sealing frame and the solder bumps is determined by the propagation of the surface acoustic wave. Create the space necessary for

[0013]

Therefore, according to the present invention, since the surface acoustic wave element chip itself is used as a part of the packaging member, it is possible to reduce the number of parts.

Further, the solder sealing frame mechanically joins the surface acoustic wave element chip and the base plate, hermetically seals the space between them, and also achieves electrical connection.
Since the electrical connection using the solder bumps can be made simultaneously with the formation of the solder sealing frame, the number of steps required for assembly can be reduced.

Furthermore, since a space is formed depending on the thickness of the solder sealing frame, a simple flat plate can be used as the base plate, so the base plate itself can be provided at low cost. can.

[0016]

[Embodiment] Surface acoustic wave device 2 according to an embodiment of the present invention
1 is shown in FIGS. 1, 2 and 3.

The surface acoustic wave device 21 first includes a surface acoustic wave element chip 22 . The surface acoustic wave element chip 22 includes a substrate 23 for propagating surface acoustic waves. The substrate 23 is made of, for example, a piezoelectric material. On the substrate 23, as shown in FIG.
and 27 and surrounding the interdigital transducers 24 and 25, and the interdigital transducer 2
Hot side patterns 31 and 32 connected to hot side lines 29 and 30 of 4 and 25 are formed. These interdigital transducers 24 and 2
5. Lines 26, 27, 29, 30 and pattern 2
8, 31, and 32 are formed by forming a metallizing film on the substrate 23 by vapor deposition or the like, and then patterning it using photolithography technology.

The surface acoustic wave device 21 includes a base plate 33 disposed opposite to the surface of the substrate 23 on which the interdigital transducers 24 and 25 of the surface acoustic wave element chip 22 described above are formed. Base plate 33 is shown alone in FIGS. 4 and 5. Note that FIG. 4 shows the top surface of the base plate 3, and FIG. 5 shows the bottom surface of the base plate 33.

The base plate 33 is made of, for example, alumina. A ground side land 34 is formed on the base plate 33 at a position corresponding to the ground side pattern 28 described above. Further, hot side lands 35 and 36 are formed at positions corresponding to hot side patterns 31 and 32, respectively. The base plate 33 also has a ground side external electrode 37 and 3 extending from the top surface to the bottom surface.
8 and hot side external electrodes 39 and 40 are formed. The earth side external electrodes 37 and 38 are both electrically connected to the earth side land 34. On the other hand, the ground side external electrodes 39 and 40 pass through through holes 41 and 42 to hot side lands 35 and 36, respectively.
electrically connected to. These lands 34, 35, 36
, and the external electrodes 37, 38, 39, 40 are formed, for example, by screen printing.

As can be seen by comparing FIGS. 1 and 4,
A solder sealing frame 43 is provided on the ground side land 34, and solder bumps 4 are provided on the hot side lands 35 and 36.
4 and 45 respectively. These solder sealing frame 43 and solder bumps 44 and 45 are formed in the form of cream solder by screen printing, for example, during the manufacturing stage. Thereafter, as shown in FIG. 2 or 3, by heating the base plate 33 together with the surface acoustic wave element chip 22, the cream solder described above melts and then solidifies, as shown in FIG. , a solder sealing frame 43 and solder bumps 4 having a predetermined thickness are provided.
4 and 45 are formed. The solder sealing frame 43 connects the earth side pattern 28 and the earth side land 34, the solder bump 44 connects the hot side pattern 31 and the hot side land 35, and the solder bump 45 connects the hot side pattern 31 and the hot side land 35. The side pattern 32 and the hot side land 36 are connected. Therefore, the ground side pattern 28 and the hot side pattern 31 formed on the surface acoustic wave element chip 22
and 32 are a solder sealing frame 43 and a solder bump 44
and 45, respectively, the ground side external electrode 37
and 38 and the hot side external electrodes 39 and 40.

The solder used for the solder sealing frame 43 and the solder bumps 44 and 45 is preferably one with a high melting point. This is because the obtained surface acoustic wave device 21
This is to prevent it from being remelted due to the soldering temperature used when mounting it on a circuit board (not shown).

As described above, according to this embodiment, the formation of a space necessary for the propagation of surface acoustic waves, high airtightness, and electrical connection can be achieved between the surface acoustic wave element chip 22 and the base plate 33.
and a solder sealing frame 43 and solder bumps 44 and 45.

FIG. 6 shows a surface acoustic wave device 21a according to another embodiment of the invention. Note that although FIG. 6 is a sectional view corresponding to FIG. 3 described above, elements corresponding to those shown in FIG. 3 are given the same reference numerals and redundant explanations will be omitted.

In FIG. 6, the base plate 33 has no through holes formed therein. Therefore, for example, the hot-side land 35 connected to the solder bump 44 is drawn out to the hot-side external electrode 39 through the upper surface of the base plate 33 . On the other hand, the ground side land 34 connected to the solder sealing frame 43 is formed to intersect with the hot side land 35 with an insulating film 46 interposed therebetween.

[Brief explanation of drawings]

FIG. 1: Surface acoustic wave device 21 according to an embodiment of the present invention.
FIG.

FIG. 2 is a perspective view showing the appearance of the surface acoustic wave device 21 shown in FIG. 1 in a completed state.

FIG. 3 is a cross-sectional view along line III-III in FIG. 2;

FIG. 4 is a top view showing the base plate 33 alone.

FIG. 5 is a bottom view showing the base plate 33 alone.

FIG. 6: Surface acoustic wave device 2 according to another embodiment of the present invention.
FIG. 4 is a cross-sectional view corresponding to FIG. 3 and showing part 1a.

FIG. 7 is a sectional view showing a conventional surface acoustic wave device 1.

[Explanation of symbols]

21, 21a Surface acoustic wave device 22 Surface acoustic wave element chip 23 Substrate 24, 25 Interdigital transducer 26
, 27 Earth side line 28 Earth side patterns 29, 30 Hot side lines 31, 32 Hot side pattern 33 Base plate 34 Earth side lands 35, 36 Hot side lands 37, 38 Earth side external electrodes 39, 40 Hot side external electrodes 41, 42 Through hole 43 Solder sealing frame 44, 45 Solder bump 46 Insulating film

Claims (1)

[Claims] 1. A substrate, an interdigital transducer formed on the substrate, and a grounding pattern connected to a grounding line of the interdigital transducer and formed on the substrate so as to surround the interdigital transducer. and a surface acoustic wave element chip comprising a hot side pattern connected to the hot side line of the interdigital transducer, and the surface acoustic wave element chip is disposed opposite to the surface of the substrate on which the interdigital transducer is formed. A ground-side land formed at a position corresponding to the ground-side pattern, a hot-side land formed at a position corresponding to the hot-side pattern, and electrically connected to the ground-side land. a base plate including a ground-side external electrode and a hot-side external electrode electrically connected to the hot-side land; and a solder sealing frame provided to connect the ground-side pattern and the ground-side land. and a solder bump provided to connect the hot side pattern and the hot side land.