JP4858985B2 - Surface acoustic wave filter package - Google Patents

Description

  The present invention relates to a surface acoustic wave filter package in which an electronic component is mounted face-down on a multilayer resin printed wiring board.

  In recent years, development of small wireless communication devices centering on mobile phone devices has become active. In order to meet the demand for further miniaturization and higher performance of these communication devices, a duplexer using a surface acoustic wave filter has been developed.

An example of such a duplexer is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-167389. In this duplexer, first and second surface acoustic wave filters having different pass bands are accommodated with their back surfaces fixed to a package (for example, FIG. 5 of the publication). The terminals of the surface acoustic wave filter and the terminals of the package are connected by a wire bonding method (for example, the sixth column, lines 21 to 24 in the publication). The package is made of box-shaped ceramics (for example, the sixth column, the eleventh line of the publication). The two surface acoustic wave filters are connected in parallel to a common external signal terminal T ₀ (also referred to as a common electrode) of the package. However, the common electrode and the first surface acoustic wave filter are connected via a first wiring branched from the common electrode via a branch point, while the common electrode and the second surface acoustic wave filter are connected. The filter is connected via a second wiring branched from the common electrode via a branch point and an impedance circuit M connected thereto (for example, FIG. 1 of the publication). The impedance matching circuit prevents a transmission signal to be output from the first surface acoustic wave filter to the common terminal from flowing into the second surface acoustic wave filter side, and the second elastic signal from the outside via the common terminal. This is a circuit that efficiently inputs a received signal to be input to the surface acoustic wave filter to the second surface acoustic wave filter.

  Further, as a surface acoustic wave filter mounting structure not related to a duplexer, as disclosed in Japanese Patent Laid-Open No. 5-160664, a metal bump formed on the surface acoustic wave filter is used. There is a structure for connecting between the electrode terminals of the wiring on the package side. This is a so-called face-down mounting structure (for example, FIG. 5 of the publication). Since this mounting structure has advantages such as a reduction in the inductance component compared to the case of using wire bonding, it can be said that the mounting structure is excellent in electrical characteristics in a high frequency region. It can also be said that the mounting structure is suitable for miniaturization.

  By the way, in the case of a duplexer using a surface acoustic wave filter, as described above, two surface acoustic wave filters having predetermined passbands for transmission and reception are mounted in a package, and It is necessary to maintain good frequency characteristics by securing heat dissipation and airtightness. In this respect, the structure disclosed in Japanese Patent Laid-Open No. 5-167389, in which the back surface of the surface acoustic wave filter is mounted on the ceramic package, is superior in heat dissipation, and the ceramic package and the surface acoustic wave filter are Since the contact area is wide, the heat generated by the surface acoustic wave filter can be radiated well.

  However, electronic devices using surface acoustic wave filters such as duplexers for small wireless communication devices are becoming increasingly demanded for cost reduction in addition to demands for miniaturization and high performance. Yes.

  In order to satisfy this requirement, a ceramic package is not preferable because it is expensive in itself.

  Therefore, in order to solve this problem, the inventors of the present application, as shown in the schematic cross-sectional view of FIG. 6, (1) a conventional printed board such as epoxy resin, BT resin (bismaleimide triazine resin), etc. The surface acoustic wave filters 13a and 13b for transmission and reception are mounted face-down on the multilayer resin printed wiring board 11 using the resin material used for the above-mentioned (2) and the surface acoustic wave filters 13a and 13b are further mounted. A metal lid 15 having a rim portion 15a formed in a jaw shape and covered with a metal lid 15 connected to the wiring board 11 at the rim portion 15a, and a space for these surface acoustic wave filters. (Airtight space) 17 is formed, and (3) heat generated in the surface acoustic wave filter for transmission 13a is further formed between the back surface of the surface acoustic wave filter for transmission 13a and the back surface of the metal lid 15. On the lid 15 It provided a structure of the heat conduction member 19 for obtaining and Consider.

  By doing so, the cost of each of the multilayer resin printed wiring board 11 and the metal lid 15 is lower than that of the ceramic package, so that the cost of the electronic device can be reduced and the face-down mounting is achieved. Compared to the case where wire bonding is used, it is considered that the electronic device can be downsized and the electrical characteristics in the high frequency region can be improved. However, since the input power is large, it is generated in the surface acoustic wave filter 13a for transmission that generates a large amount of heat. This is because it is considered that a heat radiation path can be secured.

  In FIG. 6, 21 is a terminal for mounting electronic components provided on the wiring board 11, and 23 is a bump for mounting. However, in FIG. 6, illustration is made to such an extent that the examined electronic component can be understood, and illustration of the back surface of the wiring board and the internal conductor layer is omitted.

Here, the reason why the heat conducting member 19 is provided is as follows. When face-down mounting is performed, generally, a material called an underfill material is filled between the mounting surface of the electronic component and the substrate for the purpose of relaxing stress applied to the bump portion. This underfill material also functions to dissipate heat generated in the electronic component to the substrate side. However, since the surface acoustic wave filter uses acoustic vibration excited by a plurality of comb-shaped electrodes formed on a crystal surface such as LiTaO _3, a heat dissipation path using the above underfill material cannot be secured. This is because when the underfill material is filled, it contacts the crystal surface and changes the acoustic vibration. Then, for example, in an electronic component including a surface acoustic wave filter that generates a large amount of heat, such as a duplexer, the heat generated by the surface acoustic wave filter cannot be dissipated without any effort. This is because it has been found through experiments by the inventors according to this application that the mold electrode is thermally destroyed (see a later comparative example). The heat conducting member 19 prevents the comb-shaped electrode of the surface acoustic wave filter for transmission from being thermally destroyed.

  However, the provision of the heat conducting member 19 can surely prevent the comb-shaped electrode of the surface acoustic wave filter from being thermally destroyed. However, in terms of further reducing the temperature of the metal lid, that is, the surface acoustic wave filter. In terms of further lowering the temperature, it was not yet satisfactory.

  When a multilayer resin printed wiring board is used, the wiring board itself is also a member that ensures airtightness of the electronic component storage space 17. However, when a multilayer resin printed wiring board is simply used, there is a problem that the airtightness of the space 17 is lowered.

  Accordingly, an electronic device having a structure in which an electronic component is mounted face-down on a multilayer resin printed wiring board and the electronic component is covered with a metal lid, and has a structure that can radiate heat generated in the electronic component better than before. Electronic devices are desired.

  Further, the electronic device has a structure in which an electronic component is mounted face-down on a multilayer resin printed wiring board, and the electronic component is covered with a metal lid, and has a structure capable of suppressing a decrease in airtightness of a space for storing the electronic component. An electronic device is desired.

  Also, an electronic device having a structure in which an electronic component is mounted face-down on a multilayer resin printed wiring board and the electronic component is covered with a metal lid, and has a structure that can radiate heat generated by the electronic component better than before. In addition, an electronic device having a structure capable of suppressing a decrease in airtightness of a space for storing electronic components is desired.

  The present invention relates to a surface acoustic wave filter package in which a surface acoustic wave filter is mounted face-down on a wiring board and the surface acoustic wave filter is covered by an airtight holding body mounted on the wiring board.

The wiring board includes a filter mounting area on which the surface acoustic wave filter is mounted, an airtight holding body mounting area around the filter mounting area on which the airtight holding body is mounted, and a first provided in the filter mounting area. A through hole and a second through hole provided in the hermetic holding body mounting region, the first through hole including a conductive member, the second through hole including a first heat conductive member, The holding body is mounted on the airtight holding body mounting area on the wiring board and connected to the back surface of the surface acoustic wave filter via the second heat conducting member, and extends from the airtight holding body mounting area of the wiring board to the filter mounting area. has a conductive member and the first heat conduction member and connected to the ground electrode while being formed, the second heat conducting member, together with a thermoplastic resin which metal powder is mixed, the thickness 50 to 75 characterized in that it is a value in the range of m.

  According to the present invention, the heat generated by the surface acoustic wave filter can be effectively radiated to the wiring board on which the surface acoustic wave filter is mounted via the first heat conducting member and the second heat conducting member. it can.

  In the following, embodiments of each invention will be described with reference to an example in which each invention is applied to a duplexer using a surface acoustic wave filter. This description is made with reference to some drawings. However, the drawings used in the description only schematically show the dimensions, shapes, and arrangement relationships of the constituent components to the extent that the present invention can be understood. Moreover, in each figure, it attaches and shows the same number about the same structural component, The duplicate description may be abbreviate | omitted.

1. First Embodiment of First to Third Inventions of Electronic Device First, a first embodiment will be described with reference to FIGS.

1-1. FIG. 1 is a cross-sectional view of an electronic device according to a first embodiment cut along a thickness direction of a multilayer resin printed wiring board 11 (hereinafter also abbreviated as a wiring board 11). is there. However, it is sectional drawing which paid its attention to the cut end. However, in order to understand the structures and positions of the through hole 31 for heat dissipation, the blind through hole 41, the impedance matching circuit M, the heat radiating portion 33, and the metal film 35 for airtightness according to the present invention, a structural example is provided. It is only shown. Therefore, it is noted that the cross-sectional view shown in FIG. 1 is not a cross-sectional view obtained by cutting the conductor layers L1 to L4, which will be described later with reference to FIGS. 2 and 3, along a common line.

  First, an outline of the configuration of the electronic device according to the first embodiment will be described with reference to FIG.

  This electronic device includes a multilayer resin printed wiring board 11 (hereinafter also referred to as a wiring board 11), first and second surface acoustic wave filters 13a and 13b face-down mounted on the wiring board 11, and the elasticity thereof. A metal lid 15 that covers the surface wave filters 13a and 13b so as to form a space 17 necessary for the surface wave filters 13a and 13b. The edge 15a has a jaw shape and is connected to the wiring board 11 at the edge 15a. A heat transfer member 19 provided between the back surface of the first surface acoustic wave filter 13a and the inner surface of the cover 15 for transferring heat generated by the first surface acoustic wave filter 13a to the cover 15. , With.

  Further, in this electronic device, heat transmitted from the first surface acoustic wave filter 13a to the lid 15 is transferred to the area of the wiring board 11 where the lid edge 15a is in contact and excluding the inside of the space 17. In order to convey to the back surface, at least one through hole 31 whose inner wall is covered with a metal 31a is provided.

  Further, the electronic device includes a heat radiating portion 33 that is provided on the back surface of the wiring board 11, is connected to the through hole 31, and is configured by a conductor layer. In addition, although mentioned later for details, in the case of this embodiment, the thermal radiation part 33 is comprised by the conductor layer 51 for grounding provided in the back surface of the wiring board 11 (refer FIG.3 (B)).

  Further, this electronic device is provided with a metal film 35 in an area as wide as possible in order to maintain the airtightness of the space 17 in at least the surface of each layer of the wiring board 11 that is in contact with the space 17. Yeah. Although details will be described later, in the case of this embodiment, the metal film 35 includes terminals A1, A2, B1, and B2 for mounting the surface acoustic wave filter, and an upper grounding conductor layer 55. (See FIG. 2A).

  Note that the length of the edge 15 a of the lid 15 is larger than the inner diameter of the through hole 31. Further, the through hole 31 is filled with a heat conductive material 37 in order to efficiently transfer heat from the lid 15 to the heat radiating portion 33. Further, the edge 15 a of the lid 15 and the wiring board 11 are bonded by an adhesive 39.

1-2. Detailed Description of Each Component Next, each of the above components will be described in detail. First, the multilayer resin printed wiring board 11 can be composed of any suitable wiring board. In this embodiment, as shown in FIG. 1, a wiring board formed by laminating an upper wiring board portion 11a, a lower wiring board portion 11b and a prepreg resin 11c is used. However, the wiring board 11 in this case has conductor layers on the front and back of the upper and lower wiring board portions, and eventually has four conductor layers. The conductor layer is typically made of copper.

  These four conductor layers will be described with reference to FIGS. Here, FIG. 2A is an explanatory diagram of a conductor layer (hereinafter also referred to as a fourth layer) formed on the surface of the multilayer resin printed wiring board 11, that is, the surface of the upper wiring board portion 11a. FIG. 2B is an explanatory view of a conductor layer (hereinafter also referred to as a third layer) formed on the inner layer of the multilayer resin printed wiring board 11, here, the back surface of the upper wiring board portion 11a. FIG. 3A is an explanatory view of a conductor layer (hereinafter also referred to as a second layer) formed on the inner layer of the multilayer resin printed wiring board 11, here, the surface of the lower wiring board portion 11b. FIG. 3B is an explanatory diagram of a conductor layer (hereinafter also referred to as a first layer) formed on the back surface of the multilayer resin printed wiring board 11, that is, the back surface of the lower wiring board portion 11b.

  As shown in FIG. 3B, the first layer L1, which is the lowermost layer of the four conductor layers in the wiring board 11, includes external signal terminals T0, T1, T2, and a grounding conductor layer 51 (lower side). Of the grounding conductor layer 51). Here, the external signal terminal T0 is typically connected to an antenna. A transmission signal is input from the outside to the external signal terminal T1, and a reception signal is output from the external signal terminal T2 to a subsequent circuit. As will be described later, the external signal terminal T0 is a common electrode for the first and second surface acoustic wave filters, and may be hereinafter referred to as a common external signal terminal T0 or a common electrode.

  Further, the second layer L2 is a wiring M constituting the impedance matching circuit M as shown in FIG. Further, as shown in FIG. 2B, the third layer L3 is a wiring 53 for connecting the terminal groups. Further, as shown in FIG. 2A, the uppermost layer L4 includes terminals A1, A2, B1, and B2 for mounting the surface acoustic wave filter, and a grounding conductor layer 55 (a grounding conductor layer 55 on the upper side). Also called).

  The impedance matching circuit M of the second layer L2 and the wiring 53 of the third layer L3 are sandwiched between the grounding conductor layers 51 and 55 of the first layer L1 and the fourth layer L4 as described above. Wiring has an unbalanced stripline structure.

  Further, the external signal terminals T0, T1, T2 other than the grounding conductor layer 51 in the first layer L1 and the wiring 53 in the third layer L3 are end face through holes provided at the end of the wiring board 11. 43 (see FIG. 1).

  The wiring in the second layer L2 and the wiring 53 in the third layer L3 are also connected by end face through holes (similar structure to 43 in FIG. 1). Further, terminals A1, A2, B1, B2 for mounting the respective surface acoustic wave filters in the fourth layer L4 and the wiring 53 in the third layer L3 are blind through holes (structure 41 in FIG. 1). Connected). Here, the blind through hole is a metal that covers the inner wall of the through hole, and the upper and lower wiring board portions are filled with a prepreg resin during lamination, and the surface of the through hole is a conductor. A structure covered with layers.

  The upper ground conductor layer 55 and the lower ground conductor layer 51 are connected by the through hole 31 and the end face through hole 43 described with reference to FIG.

  However, in this case, the grounding conductor layer 51 in the first layer L1 also serves as the heat radiating portion 33 in the invention of this application, so that the external signal terminal T0, T1, T2 forming portion and the end face through hole 43 are connected. Except for the electrode (C1, C2, etc.) forming portion and the portion for forming the gap 57 necessary for insulation, it is formed on the entire surface as much as possible, that is, with as wide an area as possible. And the area | region except the part which needs to be taken out as a ground electrode of this grounding conductor layer 51, and the part which hits the approximate center of the wiring board 11 bottom face is covered with the solder resist 61.

  Using the terminals A1, A2, B1, and B2 of the wiring board 11 on the surface of the wiring board 11, that is, the fourth layer L4, the first and second surface acoustic wave filters 13a and 13b are faced. Down mounted.

  The face-down mounting structure is effective for reducing the size and thickness of a duplexer using a surface acoustic wave filter. Since the face-down mounting technique itself is known, it will not be described in detail, but an example used in the present invention will be shown below.

  First, bumps 13x are formed on input / output electrodes (including ground electrodes) of the surface acoustic wave filters 13a and 13b. The method for forming the bumps is preferably, but not limited to, a method that does not require chemical conversion treatment on the electrode structure of the surface acoustic wave filter. Here, a bump forming method by ultrasonic bonding is used. Further, although various materials can be selected for the bump, a bonding material and a bonding method that do not require cleaning after mounting the surface acoustic wave filter are desirable, and gold is used here.

  In order to prevent the generation of static electricity due to the pyroelectric effect in the surface acoustic wave filters 13a and 13b, the bumps are preferably formed on the wiring board side. This will be described in an embodiment of a later manufacturing method.

  The surface acoustic wave filters 13 a and 13 b after the bump formation are mounted using the mounting terminals A 1, A 2, B 1, and B 2 of the wiring board 11.

The first and second surface acoustic wave filters 13a and 13b to be mounted are band-pass type surface acoustic wave filters having different center frequencies. In this case, the first surface acoustic wave filter 13a is considered for transmission, and the second surface acoustic wave filter 13b is considered for reception. The first surface acoustic wave filter 13a has a center frequency of 836 MHz, for example. The second surface acoustic wave filter 13b has a center frequency of 881 MHz, for example. Each of these surface acoustic wave filters can be constituted by, for example, a known surface acoustic wave filter having a comb-shaped electrode formed of an aluminum alloy on a LiTaO ₃ substrate.

  Since the wiring relationship between the conductor layers L1 to L4 of the wiring board 11 is as described above, the first and second surface acoustic wave filters 13a and 13b mounted face-down on the wiring board 11 respectively. Is connected to the common external terminal T0 of the duplexer, and the other end is connected to the external signal terminal T1 in the first surface acoustic wave filter 13a and the second surface acoustic wave filter. 13b is connected to the external signal terminal T2. However, the second surface acoustic wave filter 13b for reception is connected to the common external terminal T0 via the impedance matching circuit M. In this way, the requirements for configuring the duplexer are met.

  Next, the details of the metal lid 15 and the structure for attaching it to the wiring board 11 will be described.

  The metal lid 15 also serves as a heat radiating member of the first surface acoustic wave filter 13a and an airtight holding member of the storage space 17 of the first and second surface acoustic wave filters 13a and 13b. As a constituent material of the lid 15, a metal material having a good thermal conductivity is preferable. At the same time, it is desirable that the metal lid 15 has an electromagnetic shielding effect. Therefore, for example, a 0.2 mm thick nickel plate is used. Of course, it is not limited to this.

  Further, the adhesive 39 for bonding the metal lid 15 and the wiring board 11 is a material that can easily transfer heat from the metal lid 15 to the through hole 31 and that the storage space 17 can be kept airtight. However, it is preferable to provide the metal lid 15 with an electromagnetic shielding effect. An example of such an adhesive is a conductive adhesive. The metal component of the conductive adhesive that is currently commercially available is often silver. Therefore, after sealing the package with a conductive adhesive containing silver as a metal component, the hermeticity of the package was evaluated by a helium leak test. Since this airtightness was good, in the duplexer of the present invention, as an adhesive for attaching the edge portion 15a of the metal lid and the wiring board 11, a conductive material containing silver powder as a metal component. An epoxy resin adhesive was used.

  Next, the heat conductive member 19 will be described. In the case of this example, since the first surface acoustic wave filter 13a is for transmission, the amount of heat generated is large because the input power is large. Therefore, the heat conducting member 19 is arranged between the back surface of the first surface acoustic wave filter 13a (the back surface with respect to the electrode arrangement surface) and the inner surface of the metal lid 15, and is generated by the first surface acoustic wave filter 13a. Heat is transmitted to the metal lid 15.

  The heat conductive member 19 is required to be a material having a high thermal conductivity and a low elastic modulus material that does not apply stress to the bump connection portion. As such a material, for example, an adhesive obtained by mixing metal powder into a thermoplastic resin can be given. An example of the metal powder at this time is silver. Of course, other metals may be used. In addition, powders such as alumina, aluminum nitride, and silicon carbide may be used instead of metal. The distance between the back surface of the surface acoustic wave filter 13a and the inner surface of the metal lid 15 is preferably small in order to reduce the thermal resistance. This distance is set to 50 to 75 μm here in consideration of the height and tolerance when the surface acoustic wave filter 13 a is mounted and the processing tolerance of the metal lid 15. Note that the area where the heat conducting member 19 is connected to the surface acoustic wave filter 13a is made as wide as possible so that the used adhesive does not enter the electrode surface side of the surface acoustic wave filter 13a (substantially the entire back surface of the surface acoustic wave filter). It is preferable to reduce the thermal resistance of the heat conducting member 19.

  The heat conductive material filled in the through hole 31 is preferably a material having high heat conductivity. For example, a conductive epoxy resin adhesive having silver powder as a metal component exemplified as the adhesive 39 between the metal lid 15 and the wiring board 11 may be used.

1-3. Explanation of Effect The heat radiation and airtight performance of the duplexer of the first embodiment will be described in detail below.

  First, the heat radiation path in the above duplexer will be described. Heat generated in the vicinity of the comb electrode of the first surface acoustic wave filter 13a is transferred to the back surface of the surface acoustic wave filter 13a by conduction. Further, part of the generated heat is transmitted to the metal film 35 (see FIG. 1) of the wiring board 11 via the bumps 13x. However, the latter heat dissipation path has a higher thermal resistance than the former heat dissipation path. Accordingly, most of the generated heat is transmitted from the back surface of the surface acoustic wave filter 13a to the metal lid 15 via the heat conducting member 19, and a part of the heat is radiated from the surface of the metal lid 15 into the atmosphere. To be dissipated. The remaining heat is transferred from the edge 15a of the metal lid 15 via the adhesive 39 to the conductor layer 55 (see FIG. 2A) of the fourth layer L4. Since the through hole 31 is arranged directly below 15a and the high thermal conductivity material 37 is filled in the through hole, the heat resistance is low. After being transmitted to 33 (see FIG. 1), it is dissipated to, for example, a mother board on which the duplexer is mounted. Further, in the first layer L1 of the wiring board 11, as described with reference to FIG. 3B, the grounding conductor on the lower side is formed by the uncovered portion of the solder resist 61 disposed at the approximate center of the wiring board 11. Since the layer 51 is exposed, this also improves heat dissipation.

  In the duplexer having the structure according to the first embodiment of the present invention having the heat dissipation path as described in detail above, when the thermal conductivity of the heat conducting member 19 is about 30 W / m · K, The temperature rise was 12 ° C. per 1 W of high-frequency power input to the first surface acoustic wave filter 13a. This is a low temperature rise characteristic as compared with the case where the through hole 31 and the heat radiating portion 33 are not provided. Therefore, it can be seen that when the through hole 31 and the heat radiating portion 33 are provided, the temperature of the metal lid, that is, the temperature of the surface acoustic wave filter can be lowered as compared with the case where the through hole 31 and the heat radiating portion 33 are not provided.

  Further, even when 5 W of high frequency power is supplied to the first surface acoustic wave filter 13a of this duplexer, the thermal destruction of the comb-shaped electrode does not occur. No change in the characteristics of the surface wave filter was observed. On the other hand, when the heat conducting member 19 was not provided, the comb-shaped electrode was destroyed at the level where 2 W of high frequency power was input. The necessity of the heat conductive member 19 can also be understood.

  Next, the airtight performance will be described in detail. In the case of the conventional ceramics package, it was easy to ensure airtightness from the material characteristics. However, in the case of a package using a resin substrate as in the present invention, it is difficult to ensure high airtightness. Therefore, in the present invention, as described above, the surface of the wiring board 11 is as much as possible on the surface of the wiring board 11 so that the member forming the space for housing the first and second surface acoustic wave filters 13a and 13b is made of a metal material as much as possible. The metal film 35 (see FIG. 1) is arranged in a large area. Of course, all the wirings introduced into the space 17 for housing the surface acoustic wave filter are introduced using blind through holes, and the through-through holes do not cover the spaces 17. As a result, the leak rate from the wiring board 11 side can be reduced as much as possible.

In addition, the conductive epoxy resin adhesive using silver powder as a metal component used as the adhesive 39 between the metal lid 15 and the wiring board 11 has a specific resistance value of 2 × 10 ⁻³ Ω after bonding.・ It was cm and the adhesive strength was excellent.

From these facts, in the duplexer of the first embodiment, the first temperature condition is −40 ° C. and 30 minutes, and the second temperature condition is 85 ° C. and 30 minutes. Even when a thermal shock test was performed for 100 cycles and a helium leak test was performed thereafter, the leak rate was 1 × 10 ⁻⁸ atm · cc / sec and there was no change from the initial value. Further, no corrosion of the comb electrode due to poor airtightness occurred.

  Therefore, according to the present invention, it is understood that practical airtightness can be realized despite the electronic device using the multilayer resin printed wiring board as a part of the package.

2. 2. Second Embodiment of First to Third Inventions of Electronic Device 2-1. Description of Configuration FIG. 5 is a cross-sectional view illustrating a duplexer according to a second embodiment. In the second embodiment, the heat conducting member 71 is constituted by a predetermined metal foil 71. Other configurations are the same as those in the first embodiment. Therefore, in the following description, the heat conductive member 71 will be mainly described.

  The metal foil as the heat conducting member 71 is a metal foil having a bent portion 71a at the substantially central portion thereof, and the thickness thereof is, for example, about 50 to 100 μm. The material is a material having high thermal conductivity and high flexibility. Although not limited to this, copper etc. are suitable, for example. Further, the width of the metal foil 71 is set such that the metal foil 71 enters the space formed by the metal lid 15 and larger than the width of the back surface of the surface acoustic wave filter 13a. Further, the height (vertical dimension in FIG. 5) of the bent portion 71a is made the same as or slightly smaller than the thickness of the surface acoustic wave filter 13a. However, the bending portion 71a is processed so that it can be inserted into the gap between the first and second surface acoustic wave filters 13a and 13b with a slight gap (margin).

  The heat conducting member 71 is mounted as follows, for example. One end of the heat conducting member 71 is connected to the back surface of the first surface acoustic wave filter 13a with the first adhesive 73, and the other end is connected to the inner surface of the metal lid 15 with the second adhesive 75. is there.

  As the second adhesive 75, for example, a silver-based conductive adhesive based on the thermoplastic resin used as the heat conductive member in the first embodiment described above can be used. The first adhesive 73 is preferably non-conductive and highly heat conductive. This is because the non-conductive side has less electrical adverse effects when it wraps around the electrode forming surface of the surface acoustic wave filter 13a. Examples of the non-conductive and thermally conductive adhesive include an adhesive based on a thermoplastic resin mainly composed of alumina or the like.

  The bonding area of the heat conducting member 71 is substantially the entire surface of the back surface of the surface acoustic wave filter 13a, and approximately the entire surface of the metal lid 15 in contact with the metal lid 15 on the metal lid 15 side. Good to do.

  Note that the second adhesive 75 may be the same adhesive as the first adhesive 73. In that case, it is necessary to control the amount of the adhesive so that the adhesive does not enter the electrode forming surface of the surface acoustic wave filter 13a.

  Further, the gap between the metal lid 15 and the back surface of the surface acoustic wave filter 13a is made larger than that of the first embodiment by the thickness of the metal foil 71.

2-2. Description of Effect In the duplexer of the second embodiment, the metal foil 71 is used as the heat conducting member, but the heat dissipation path itself is obtained in the same manner as in the first embodiment. Therefore, as in the first embodiment, the temperature of the metal lid, that is, the temperature of the surface acoustic wave filter can be reduced as compared with the case where the through hole 31 and the heat radiating portion 33 are not used.

  Actually, when a copper foil having a thickness of 50 μm is used as the metal foil 71 and an adhesive having a thermal conductivity of about 30 W / m · K is used as the first and second adhesives 73 and 75, the demultiplexing is performed. The temperature rise of the vessel package was 18 ° C. per 1 W of high frequency power input to the first surface acoustic wave filter 13a. This is a low temperature rise characteristic as compared with the case where the through hole 31 and the heat radiating portion 35 are not provided.

  Further, as to the airtightness in the second embodiment, good characteristics similar to those in the first embodiment were obtained.

  Further, in the case of the second embodiment, the following effects are also obtained. One end of the heat conducting member 71 is connected to the inner surface of the metal lid 15 with a conductive adhesive 75, and the edge 15 a of the lid is connected to the upper-side grounding conductor layer 55 ( 2 (A)) and the conductive adhesive 39 are connected. Therefore, the heat conducting member 71 is at the same potential as the grounding conductor layer. Therefore, since the bent portion 71a of the heat conducting member 71 functions as an electric field shield for the first and second surface acoustic wave filters 13a and 13b, for example, it is possible to reduce the adverse effect between the transmission signal and the reception signal. Can be obtained. However, since it is considered that the bent portion 71a exhibits stress absorption, it is considered that the influence of stress on the surface acoustic wave filter caused by the heat conducting member 71 can be reduced.

3. Fourth Embodiment of Electronic Device Next,. Invention for shortening the wiring length between the branch point DP where the wiring from the common external signal terminal T0 branches into the first and second surface acoustic wave filters 13a and 13b and the first surface acoustic wave filter 13a Will be described. This description is mainly given with reference to FIGS. 1, 2 and 4. FIG.

  When a duplexer is configured using two surface acoustic wave filters having different pass bands, a branch point DP is provided in the middle of the wiring from the common external signal terminal T0, as shown in FIG. There is a configuration in which a surface acoustic wave filter 13a for transmission is connected to one side branched in the above, and a surface acoustic wave filter 13b for reception is connected to the other side via an impedance matching circuit M as a branching circuit.

  In this case, if the wiring from the transmission signal output terminal of the first surface acoustic wave filter 13a for transmission to the branch point DP is long, a change in impedance characteristics, a phase shift, and reflection of the transmission signal occur in this wiring part. It is not preferable.

  In order to alleviate this, in the present invention, a blind through hole 41 (see FIG. 1) leading to the surface of the wiring board 11 is formed in the wiring board portion in contact with the branch point DP, specifically, the upper wiring board portion 11a in FIG. 1). However, a terminal A1 (see FIG. 2A) for mounting the first surface acoustic wave filter 13a is provided on or near the blind through hole 41. Then, a transmission signal output terminal of the first surface acoustic wave filter 13a is mounted on the terminal A1. As a result, the wiring connecting the branch point DP and the first surface acoustic wave filter 13a (the first wiring in the present invention) is a very short wiring such as approximately the length of the blind through hole 41. Become.

  On the other hand, the connection between the branch point DP and the second surface acoustic wave filter 13b is as follows. (1) The wiring 53 (the first electrode in this invention) from the branch point DP in FIG. 2B to the end face through-hole connection electrode C1. 2), and (2) an impedance matching circuit M connected to the end face through-hole connection electrode C1 in FIG. ) And (3) a wiring 53 connected to the terminal through-hole connection electrode C2 in FIGS. 3A and 2B to the terminal (B2 ′) in FIG. 4) A blind through hole (not shown) that leads from the terminal (B2 ′) to the terminal B2 (see FIG. 2A) on the surface of the wiring board 11 is performed.

  In the branching filter of this embodiment, the length of the wiring (first wiring) between the branch point DP and the first surface acoustic wave filter 13a is set to the thickness of the upper wiring board portion 11a, for example, , About 200 to 300 μm. Therefore, compared to the conventional branching filter using wire bonding and the branching circuit with a long wiring length from the branching point of the branching circuit, unnecessary impedance characteristic change and phase shift can be reduced. It is possible to exhibit good demultiplexing characteristics.

4). Embodiment of Manufacturing Method of Electronic Device Next, an embodiment of a manufacturing method capable of preventing the destruction of the comb electrode due to static electricity caused by the pyroelectric effect in the electronic device including the surface acoustic wave filter will be described.

  In the conventional manufacturing method, as described in the first embodiment, bumps are formed on the input / output (including ground) electrodes of the surface acoustic wave filter. Since the comb-shaped electrode of the surface acoustic wave filter is a very fine wiring, the formation method is preferably a method that does not require a chemical conversion treatment, an etching treatment, etc., and applied an ultrasonic wire bonding method, specifically a ball bonding method. It was common to perform bump formation. Thereafter, a method of bonding a surface acoustic wave filter with a bump electrode to a package substrate was used. However, in the bump forming process using the wire bonding method, the surface acoustic wave filter is exposed to a temperature of 150 ° C. to 180 ° C. during the processing, and thus is generated by a pyroelectric effect peculiar to the piezoelectric material in the cooling process after the processing. There was a problem that the comb electrode of the filter was destroyed by the static electricity. The destruction phenomenon is more likely to occur as the size of the wafer on which the surface acoustic wave filter is formed increases. Further, such a destruction phenomenon has significantly reduced the production yield of the surface acoustic wave filter. Therefore, in the manufacturing method of the present invention, the following procedure is taken.

  In this new manufacturing method, bump formation is first performed on the wiring board 11 side. The forming method may be a conventional ultrasonic wire bonding method, or a plating method, an etching method, a transfer method, or the like can be selected. However, when mass productivity is considered, the electrolytic plating method is preferable.

  When a surface acoustic wave filter is mounted on the wiring board 11 after bump formation in this way, the following procedure is taken in this new manufacturing method.

  A surface acoustic wave filter that has been subjected to a predetermined electrode surface treatment corresponding to the connection method is aligned with the bumps on the wiring board 11 and then connected. At this time, each external signal terminal on the wiring board 11 and the GND electrode are connected (short-circuited) using a jig in advance. If it carries out like this, the surface acoustic wave filter mounted in the wiring board 11 will be in the state by which the comb electrodes were short-circuited. In such a state, face-down mounting work, specifically, predetermined connection processing (thermal history) can be performed.

  In the invention of this manufacturing method, during the bonding of the surface acoustic wave filter to the wiring board (package substrate), the comb-shaped electrodes of the surface acoustic wave filter are connected to each other by the connecting material, the wiring in the wiring board, each external signal terminal, the jig. Since it is short-circuited through the tool, all static electricity due to the pyroelectric effect generated in the surface acoustic wave filter due to the bonding thermal history is neutralized. Therefore, destruction of the comb electrode does not occur. Therefore, the production yield can be improved.

  Each invention of this application is not limited to the above-described embodiment, and many modifications or changes can be made.

  For example, a structure in which a through hole 31 for heat dissipation and a heat dissipation portion 33 are provided, or a structure in which a metal film 35 for maintaining airtightness in the electronic component storage space 17 is provided in a duplexer using a surface acoustic wave filter. The present invention is not limited to this, and can be widely applied to electronic devices in which electronic components are mounted face-down using a multilayer resin printed wiring board and have the same problems as the above-described duplexer.

It is explanatory drawing mainly of 1st Embodiment of an electronic device, and is sectional drawing which showed the example of the internal structure of this electronic device especially. It is explanatory drawing of 1st Embodiment of an electronic device, and is a figure (the 1) explaining the conductor layer provided in a multilayer resin printed wiring board especially. It is explanatory drawing of 1st Embodiment of an electronic device, and is a figure (the 2) explaining the conductor layer provided in a multilayer resin printed wiring board especially. It is explanatory drawing of the duplexer using a surface acoustic wave filter. It is explanatory drawing of 2nd Embodiment of an electronic device, and is sectional drawing which showed the example of the internal structure of this electronic device especially. It is a figure for demonstrating a subject.

Explanation of symbols

11: Multilayer resin printed wiring board 13a: First surface acoustic wave filter 13b: Second surface acoustic wave filter 15: Metal lid 15a: Edge of lid 17: Space 19: Thermal conduction member 31: Through hole 31a : Metal covering the inner wall of the through hole 33: Heat radiation part 35: Metal film provided in the space 37: Thermally conductive material 39: Adhesive 41: Blind through hole T0: Shared external signal terminal (common electrode)
DP: Branch points A1, A2, B1, B2: Electronic component mounting terminals (electrodes connected to the electronic components)
71: Heat conductive member made of metal foil 71a: Bending part

Claims (4)

A surface acoustic wave filter package in which a surface acoustic wave filter is mounted face-down on a wiring board, and the surface acoustic wave filter is covered by an airtight holding body mounted on the wiring board,
The wiring board is provided in a filter mounting area on which the surface acoustic wave filter is mounted, an airtight holding body mounting area around the filter mounting area on which the airtight holding body is mounted, and the filter mounting area. A first through hole formed, and a second through hole provided in the airtight holding body mounting region,
The first through hole includes a conductive member,
The second through hole includes a first heat conducting member,
The airtight holding body is mounted on the airtight holding body mounting region on the wiring board and connected to the back surface of the surface acoustic wave filter via a second heat conducting member,
A ground electrode connected to the previous SL first heat conducting member from said gas-tight seal member mounting region together when formed across the filter mounting region of the wiring board,
The surface acoustic wave filter package, wherein the second heat conducting member is a thermoplastic resin mixed with metal powder and has a thickness in the range of 50 to 75 m .   2. The surface acoustic wave filter package according to claim 1, wherein an edge portion of the hermetic holding member which is connected to the wiring board in a jaw shape covers the entire opening of the second through hole.   3. The surface acoustic wave filter package according to claim 1, wherein the second heat conducting member is disposed on the entire back surface of the surface acoustic wave filter. The pre-Symbol airtightness body and the gas-tight seal member mounting region which is formed on the ground electrode, one of the claims 1 to 3, characterized in that it is electrically connected through the first heat conducting member A surface acoustic wave filter package according to claim 1.

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