JP4811233B2 - Electronic component package - Google Patents

Description

  The present invention relates to an electronic component package in which a surface acoustic wave element is covered with a mold resin.

  FIG. 13 shows a SAW (surface acoustic wave) filter 1 as an electronic component, and shows a conventional electronic component package.

  As described above, the conventional electronic component package includes the component substrate 2, the IDT electrode 3 as a surface acoustic wave element disposed on the lower surface of the component substrate 2, and the component cover 4 that covers the lower portion of the component substrate 2. A cavity 5 is formed between the electrode 3 and the component cover 4 for holding the vibration space of the elastic wave in an airtight state.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
JP-A-1-209811

  In recent years, in the conventional electronic component package as described above, there has been a problem that frequency characteristics deteriorate due to unnecessary waves (hereinafter referred to as bulk waves) that do not propagate on the surface of the component substrate 2.

  This is mainly due to the large difference in acoustic impedance between the component substrate 2 on which the IDT electrode 3 is provided and its peripheral portion.

  That is, the IDT electrode 3a on the input side emits not only the surface acoustic wave but also a bulk wave propagating through the component substrate 2, and this bulk wave is reflected by the side surface of the component substrate 2 and reaches the output transducer. This bulk wave is also detected by the IDT electrode 3b on the output side, and the frequency characteristics of the SAW filter 1 are deteriorated.

  The reflection of the bulk wave on the side surface of the component substrate 2 is remarkably different in elasticity between the component substrate 2 and the peripheral portion of the component substrate 2 (air in FIG. 13), and the component substrate is proportional to this. This is because the difference in acoustic impedance from 2 to the outside air increases and the reflection increases accordingly.

  In particular, in recent years, electronic components have been miniaturized, and the distance between the IDT electrode 3 and the side surface of the component substrate 2 has been shortened. Thus, the problem that the frequency characteristics are deteriorated due to bulk waves has become apparent.

  Therefore, an object of the present invention is to reduce the deterioration of frequency characteristics due to bulk waves and improve the frequency characteristics of electronic components.

In order to achieve this object, the present invention provides an electronic component package in which an electronic component mounted via an external electrode disposed on a mounting substrate is covered with a mold resin. The electronic component is a component made of a piezoelectric body. The IDT electrode disposed on the lower surface of the substrate is covered with a component cover, and an intermediate elastic layer having an elastic modulus smaller than that of the component substrate and larger than that of the mold resin is provided between the upper surface of the component substrate and the mold resin. It is.

  According to such a configuration, the elastic modulus decreases (soft) in the order of the component substrate, the intermediate elastic layer, and the mold resin from the inside to the outside of the electronic component, and the acoustic impedance of the bulk wave is smoothly changed in this order. be able to. Therefore, the bulk wave that reaches the side surface of the component board can be smoothly propagated from the component board to the intermediate elastic layer, and from the intermediate elastic layer to the mold resin. As a result, the bulk wave inside the component board is reduced. In addition, the frequency characteristics of the electronic component can be improved.

(Embodiment 1)
The electronic component package of the first embodiment will be described by taking an elastic wave device for an antenna duplexer (hereinafter referred to as SAW duplexer 6) as an example of the electronic component.

  As shown in FIG. 1, the SAW duplexer 6 includes a component substrate 7, an IDT electrode 8 serving as a resonance element disposed on the lower surface of the component substrate 7, and a component cover 9 that covers the lower portion of the component substrate 7. Yes. A concave portion 10 is provided in a portion of the upper surface of the component cover 9 facing the IDT electrode 8. In addition, this recessed part 10 forms the cavity 11 used as the vibration space of the surface acoustic wave which propagates between the IDT electrodes 8. FIG. Further, the side surface of the component substrate 7 is a work-affected layer 12, and a protective body 13 is disposed on the upper surface of the component substrate 7. As shown in the enlarged view of FIG. 2, the work-affected layer 12 refers to a concavo-convex portion generated by plastic deformation of the surface of the component substrate 7 that receives mechanical energy during cutting.

  Further, the SAW duplexer 6 is mounted on the mounting substrate 14 via the external electrode 15 on the mounting substrate 14, and an electronic component package is formed by covering the mounting substrate 14 with a mold resin 16.

As the mold resin 16 and the protector 13, an epoxy resin containing a SiO ₂ filler was used.

In the present embodiment, the component substrate 7 is formed using LiTaO ₃ , the component cover 9 is formed of silicon, and the IDT electrode 8 is formed of aluminum.

In addition, a piezoelectric material such as LiNbO ₃ may be used as the material for the component substrate 7, and other metal materials may be used as the material for the IDT electrode 8.

  In this electronic component package, an intermediate elastic layer 17 in which the elastic modulus of the work-affected layer 12 and the protective body 13 is smaller than the elastic modulus of the component substrate 7 and larger than the elastic modulus of the mold resin 16 is formed. By interposing this intermediate elastic layer 17 between the resin and the mold resin 16, it is possible to reduce the deterioration of the frequency characteristic due to the bulk wave and improve the frequency characteristic of the electronic component.

  That is, by interposing the intermediate elastic layer 17 between the component substrate 7 and the mold resin 16, the change in elastic modulus in the bulk wave emission path from the component substrate 7 to the mold resin 16 is sequentially reduced. The elastic modulus changes smoothly from the substrate 7 to the mold resin 16.

  As the elastic modulus changes, the acoustic impedance of the bulk wave can be changed smoothly in the order from the component substrate 7 to the mold resin 16, and as a result, the bulk wave reaching the side surface of the component substrate 7 is From the component substrate 7 to the intermediate elastic layer 17, and further from the intermediate elastic layer 17 to the mold resin 16, it can be smoothly propagated to the outside of the electronic component, reducing the deterioration of the frequency characteristics due to the bulk wave, This is because the frequency characteristics can be improved.

  In forming the intermediate elastic layer 17, the work-affected layer 12 is used on the side surface of the component substrate 7, and the protective body 13 is used on the upper surface of the component substrate 7. The manufacturing method will be described below.

  First, the wafer-like component substrate 7 is divided into a plurality of sections. FIG. 3 shows one of these sections. Then, aluminum is vapor-deposited and sputtered on the entire lower surface of the wafer-like component substrate 7, and then an electrode pattern such as the IDT electrode 8 is formed by dry etching. In addition, although it is common to arrange | position the reflector which has arrange | positioned the short circuit electrode in parallel at the both ends of the IDT electrode 8, it has shown it simplified.

  Next, a photosensitive resin layer 18 is formed on the entire component substrate 7 as shown in FIG. 4B on the component substrate 7 in a wafer state on which a predetermined electrode pattern such as the IDT electrode 8 shown in FIG. 4A, and a mask 19 is used to mask portions other than a portion corresponding to a predetermined electrode pattern such as the IDT electrode 8, and the exposure and development are performed so that only the unmasked portion is photosensitive as shown in FIG. The resin layer 18 remains cured and does not remain on the masked portion.

Thereafter, as shown in FIG. 4 (d), SiO ₂ is sputtered on the entire upper surface of the component substrate 7, and then the component substrate 7 is immersed in a stripping solution or the like to dissolve the photosensitive resin layer 18 and dissolve the component. Drop off from the substrate 7. Then, as shown in FIG. 4 (e), SiO ₂ remains only in the portion without the photosensitive resin layer 18, that is, the portion other than the IDT electrode 8 and the extraction electrode (not shown), and the remaining SiO ₂ is bonded. This is part 19.

  On the other hand, as shown in FIG. 4 (f), the component cover 9 has a recess 10 formed on the bottom surface of the silicon plate facing the IDT electrode 8 by dry etching or sandblasting. An assembly of SAW duplexers 6 can be formed by directly bonding atoms between the substrate 7 and the substrate via the bonding portion 19 at room temperature. In the present embodiment, the process of bonding the component cover 9 is performed in a vacuum.

  Next, as shown in FIG. 5A, the assembly of the SAW duplexers 6 is inverted, and the protective body 13 is disposed on the upper surface of the component substrate 7. At this time, the protective body 13 and the component substrate 7 may be lightly pressed (2 atm to 3 atm) and bonded to each other so as to be in close contact with each other.

  Thereafter, as shown in FIG. 5B, the rotating blade 20 is used to cut and separate the electronic component from the upper surface of the protection body 13 to the lower surface of the component cover 9. In addition, this rotary blade 20 has diamond abrasive grains attached thereto, and the rotary blade 20 has an abrasive grain count of # 1000 to # 2000. The cutting speed of the rotary blade 20 was about 10 mm per second (spindle speed 5000 to 6000 rpm).

  Next, as shown in a sectional view of the SAW duplexer 6 in FIG. 6 (BB cross section in FIG. 3), a through hole 21 is provided in the component cover 9 by dry etching, and Ti, Ni are formed inside the through hole 21. Then, Au is sequentially deposited to form a metal film, and solder is printed inside the metal film to form the external terminal connection portion 22. Next, the receiving terminal 23, the antenna terminal 24, the transmitting terminal 25, and the ground terminal 26 of FIG. 7 bonded to the external electrode 15 of the mounting substrate 14 are formed on the lower surface of the external terminal connecting portion 22.

  FIG. 7 is a bottom view of the component cover 9 and shows the arrangement positions of the reception terminal 23, the antenna terminal 24, the transmission terminal 25, and the ground terminal 26 that are joined to the external electrode 15.

  Then, as shown in FIG. 1, the SAW duplexer 6 described above is mounted on the mounting substrate 14 via the external electrode 15, and then the SAW duplexer 6 is placed in a mold and the mold resin 16 heated in the mold is heated. Is injected at a resin temperature of 175 ° C. and an injection pressure of 50 to 100 atm, and then cooled to form an electronic component package.

  In such a manufacturing process, the work-affected layer 12 to be the intermediate elastic layer 17 on the side surface of the component substrate 7 shown in FIG. 2 is used as the wafer-like SAW duplexer 6 using the rotary blade 20 shown in FIG. In the step of cutting / separating, by setting the count of the abrasive grains of the rotary blade 20 to # 1000 or more and # 2000 or less, fine irregularities are formed on the cut surface, and the mold resin 16 enters the irregularities to form a hybrid structure. As a result, the work-affected layer 12 having an elastic modulus smaller than that of the component substrate 7 and larger than that of the mold resin 16 is formed. Therefore, the intermediate elastic layer can be easily formed on the side surface of the component substrate 7 without providing a special process. 17 can be provided.

  Further, the protective body 13 which becomes the intermediate elastic layer 17 on the upper surface of the component substrate 7 can be easily formed such that it is placed on the surface of the wafer-like assembly as previously extended and lightly pressed. It can be done.

  When the protector 13 is placed on the upper surface of the component substrate 7, lightly pressing (2 atm to 3 atm) is generally performed on the surface of the component substrate 7 with fine irregularities by polishing as shown in FIG. Therefore, the protective body 13 and the component board 7 are not in close contact with each other only by placing the protective body 13 at normal pressure, and air is interposed between the projections and depressions, and the acoustic impedance of this air is significantly different from that of the component board 7. Since the bulk wave 27 is almost reflected at the interface between the component substrate 7 and the protection body 13 due to the difference, the protection body 13 is also applied to the unevenness of the component substrate 7 by pressing when the protection body 13 is arranged. It is possible to increase the penetration and adhesion degree, to reduce the presence of air in which the acoustic impedance is significantly separated from the component substrate 7, and to increase the transmission amount of the bulk wave 27 from the component substrate 7 to the protective body 13. . Therefore, the integrated attenuation amount of the bulk wave 27 can be increased, and as a result, the frequency characteristics of the electronic component can be improved.

  Further, the protective body 13 can achieve a thin electronic component.

  That is, conventionally, in order to attenuate the bulk wave 27 described above, a means for increasing the thickness of the component substrate 7 and increasing the propagation distance of the bulk wave has been taken. However, unlike the component substrate 7 having a single crystal structure, since the protector 13 is made of resin, the molecular structure thereof is less regular. To increase. Therefore, if the attenuation rate of the same bulk wave 27 is to be obtained, it is possible to make the protective body 13 thinner than the case of using only the component substrate 7.

  In this embodiment, an epoxy resin containing a filler 28 is used as the protector 13 as shown in FIG. 8, but it has good adhesiveness with the component substrate 7 and has an elastic modulus enough to suppress the deflection of the component substrate 7. Other materials may be used as long as they have the following. In addition, when using resin as the protection body 13, since the elastic modulus of the general resin tape which does not contain the filler 28 is less than 3 GPa, it is preferable to make the resin contain the filler 28 and to make the elastic modulus 3 GPa or more. Moreover, since the adhesiveness will worsen when the filler 28 is increased too much when using an epoxy resin, the content rate of the filler 28 is desirable 20 wt%-50 wt%.

(Embodiment 2)
The difference between the second embodiment and the first embodiment is that, as shown in FIG. 9, the dummy electrode 29 is disposed in a portion corresponding to the lower portion of the cavity 11, and the damage of the SAW duplexer 6 due to the external pressure is suppressed. can do. This is particularly effective for a thin and easily damaged electronic component having a cavity 11 because it needs to be pressed when the protective body 13 is provided.

  That is, since the dummy electrode 29 serves as a support between the mounting substrate 14 and the SAW duplexer 6, the external pressure applied to the component cover 9 can be effectively dispersed. Therefore, as a result, the strength of the electronic component package against external pressure can be improved, and damage to the SAW duplexer 6 can be prevented.

  Further, when a plurality of IDT electrodes 8 are formed on the component substrate 7, one cavity 11 may be provided so as to cover all the IDT electrodes 8, but as in the present embodiment, one or two cavities 11 are provided. A cavity 11 may be formed for each IDT electrode 8. In this way, the formation of a plurality of cavities 11 can suppress damage to the SAW duplexer 6.

  That is, when there is nothing to support the cavity 11 portion, when external pressure is applied to the component substrate 7 and the component cover 9, the cavity 11 may be broken and damaged. However, by dividing the cavity 11 into a plurality of parts, a partition wall 30 is formed between the cavities 11 and the cavity 11, and the partition wall 30 can be a support column to disperse external stress. As a result, the component substrate 7 or the component cover 9 can be prevented from cracking. The partition wall 30 may be arbitrarily formed in the cavity 11 with a resin or the like separately.

  The plurality of cavities 11 may be formed by being completely divided individually, but may be partially connected by a communication path (not shown) connected between adjacent cavities 11 by a tunnel-like path. By providing the communication path in this manner, when an excessive external pressure is applied to a part of the cavity 11, the external pressure can be dispersed to other cavities 11 through the communication path. As a result, the strength against the external pressure of the electronic component package can be improved.

  In the SAW duplexer 6 according to the present embodiment, the dummy electrode 29 is disposed in a portion facing the IDT electrode 8 and joined to the external electrode 15 of the mounting substrate 14, so that the component cover 9 and the component cover 9 are mounted below the cavity 11. The gap between the substrate 14 is reduced, and the amount of the mold resin 16 entering can be reduced. Therefore, during molding, the pressure applied from below the component cover 9 toward the cavity 11 can be reduced, and damage to the component cover 9 can be suppressed.

  Other configurations, manufacturing methods, operations, and effects are the same as those in the first embodiment, and are therefore omitted.

(Embodiment 3)
The difference between the third embodiment and the first embodiment is that, as shown in FIG. 10, the ground terminals 26 of FIG. 7 are combined into one, and the substantially entire surface excluding the receiving terminal 23, the antenna terminal 24, and the transmitting terminal 25. In addition, a large ground terminal 31 is provided.

  With such a structure, the ground terminal 31 becomes a support between the component cover 9 and the mounting substrate 14, and the external pressure can be effectively dispersed and damage to the SAW duplexer 6 can be prevented.

  This is particularly effective for an electronic component that is thin and easily damaged, such as having a cavity 11, because it is necessary to press the protective body 13.

  Further, the presence of the ground terminal 31 reduces the amount of the mold resin 16 that enters between the component cover 9 and the mounting substrate 14 by the volume of the ground terminal 31, thereby suppressing the pressure applied from below the component cover 9.

  Other configurations, manufacturing methods, operations, and effects are the same as those in the first embodiment, and are therefore omitted.

In the first to third embodiments, silicon is used as the component cover 9, but the component cover 9 may be made of sapphire, crystal, glass, epoxy resin containing filler, or the like. Further, as shown in FIG. 11, the cavity 11 is formed by using a flat plate without a concave portion as the component cover 9 and providing a bonding portion 32 such as a metal such as aluminum or SiO ₂ between the component cover 9 and the component substrate 7. May be formed. In addition, as shown in FIG. 12, an element cover 33 covering the lower part of the element (IDT electrode 8) may be provided, and the outer periphery thereof may be covered with the component cover 9. These component covers 9 have an effect of protecting the IDT electrode 8 from corrosion due to oxidation and moisture.

  Since the electronic component package according to the present invention can improve the frequency characteristics of the electronic component, the electronic component package can also be applied to an electronic component package using an elastic wave such as a SAW filter or BAW.

Sectional drawing of the electronic component package in Embodiment 1 The expanded sectional view of the electronic component package in Embodiment 1 Bottom view of component board in the first embodiment Manufacturing process diagram of SAW duplexer in Embodiment 1 Manufacturing process diagram of SAW duplexer in Embodiment 1 Sectional view of SAW duplexer in Embodiment 1 The bottom view of the component cover in Embodiment 1 Schematic diagram showing transmission and attenuation of bulk waves inside electronic components The bottom view of the component cover in Embodiment 2 The bottom view of the component cover in Embodiment 3 Sectional drawing of the electronic component package in other embodiment Sectional drawing of the electronic component package in other embodiment Sectional view of a conventional electronic component package

Explanation of symbols

6 Electronic Component 7 Component Board 8 IDT Electrode 9 Component Cover 12 Processed Alteration Layer 13 Protective Body 14 Mounting Board 15 External Electrode 16 Mold Resin 17 Intermediate Elastic Layer

Claims (4)

A mounting substrate, an external electrode disposed on the mounting substrate, an electronic component mounted on the mounting substrate via the external electrode, and a mold resin that covers the electronic component on the mounting substrate. The electronic component includes a component substrate made of a piezoelectric body, an IDT electrode disposed on a lower surface of the component substrate, and a component cover that covers a lower portion of the component substrate. The upper surface of the component substrate, the mold resin, An electronic component package comprising an intermediate elastic layer having an elastic modulus smaller than that of the component substrate and larger than that of the mold resin. The electronic component package according to claim 1, wherein the intermediate elastic layer is made of a resin having an elastic modulus of 3 GPa or more. The intermediate elastic layer is made of SiO. ₂ The electronic component package according to claim 1, wherein the electronic component package is made of an epoxy resin containing 20 wt% to 50 wt% of the filler. The electronic component package according to claim 1, wherein the intermediate elastic layer is provided between an upper surface of the component substrate and the mold resin, and between a side surface of the component substrate and the mold resin.

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