CN111342797A - Piezoelectric filter and electronic equipment having the same - Google Patents

Abstract

The invention relates to a piezoelectric filter, comprising: a first substrate; a second substrate opposite to the first substrate; a series resonator branch with a plurality of series resonators; a plurality of parallel resonator branches, each of which The parallel resonator branch has a parallel resonator, the series resonator and the parallel resonator are arranged on the first substrate; and a heat dissipation unit is arranged between two adjacent series resonators to form a heat dissipation unit from the two adjacent series resonators. The heat of at least one of the adjacent series resonators is conducted to the heat conduction path of the second substrate. The invention also relates to an electronic device having the filter.

Description

Piezoelectric filter and electronic equipment having the same

technical field

Embodiments of the present invention relate to filter devices for communication, and more particularly, to a filter having an improved thermal conduction structure, and an electronic device having the filter.

Background technique

In recent years, with the rapid development of the market, wireless communication terminals and equipment continue to develop in the direction of miniaturization and multi-mode-multi-band. Therefore, there is an increasing demand for small size, high performance filters for such products.

At present, the small-sized filters that can meet the use of communication terminals are mainly piezoelectric acoustic wave filters. The resonators that constitute such acoustic wave filters mainly include: FBAR (Film Bulk Acoustic Resonator, thin-film bulk acoustic resonator), SMR (Solidly Mounted Resonator, solid-state assembly resonator) and SAW (Surface AcousticWave, surface acoustic wave resonator). Among them, the FBAR and SMR filters manufactured based on the bulk acoustic wave principle have the characteristics of lower insertion loss and higher power capacity than the SAW filter manufactured based on the surface acoustic wave principle.

The low insertion loss of the filter can ensure that under the premise of the same antenna transmit power (specified by the international unified communication protocol), the amplifier of the transmit channel can transmit less power to save the power consumption of the terminal equipment, thereby extending the power consumption under the same power condition. It also reduces the heat generation in the transmission link, bringing a better user experience.

The filter has a higher power capacity, which means that the transmission power level of the terminal device can be appropriately increased to expand the coverage of the signal sent by the terminal, thereby reducing the network density of the operator's base station and saving the operator's networking cost. At present, supporting higher power levels has gradually become a basic requirement for 4G and even 5G communication terminals, which requires filters applied to the transmission channel and needs to have higher power capacity.

However, the generation of heat is unavoidable in the transmission channel filter, and the accumulation of heat will cause damage to the tiny structures on the resonator, which is a component unit of the filter, due to stress, deformation, and high temperature burning. Therefore, how to dissipate the heat generated by the resonator due to the high power to be dissipated at the fastest speed to improve the power capacity of the filter has become a key issue that filter design engineers need to consider.

FIG. 1 is a circuit diagram of a piezoelectric bandpass filter 100 with a trapezoidal structure that is relatively common in the prior art. Reference numeral 131 is an input port of the filter, and reference numeral 132 is an output port of the filter. Between the input port 131 and the output port 132, there is a series of series resonators 101, 102, 103, 104 in series paths, connected in series, and a series in parallel paths, connected from certain nodes on the series paths to Parallel resonators 111, 112, 113 to ground. When the frequency of the power signal is within the passband frequency range of the filter, the power signal will pass through the series resonators from the input port, and then reach the output port. It is the center of the resonance that generates heat, compared to a parallel resonator that generates relatively little heat because most of the signal does not pass through the parallel resonator.

FIG. 2 is a schematic cross-sectional view of a filter chip 200 in the prior art, in which only two series resonators located in a series path and some related structures are schematically drawn. Reference numeral 210 is a first substrate, which is mainly used for making a resonator (taking an FBAR resonator as an example) and composing a filter. Reference numeral 219 is the bottom electrode metal layer, reference numeral 213 is the piezoelectric layer over the bottom electrode, reference numerals 214 and 215 are the top electrodes over the piezoelectric layer, and reference numerals 218 and 219 are the bottom electrodes The air cavity formed on the substrate 210 below. The overlapping area of the top electrode 214, the piezoelectric layer 213, the bottom electrode 216 and the lower air cavity 218 forms a series resonator (the first series resonator); the top electrode 215, the piezoelectric layer 213, the bottom electrode 216 and the lower air The overlapping area of the cavity 219 forms another series resonator (the second series resonator); the bottom electrodes 216 of the two series resonators are the same, that is, the two series resonators are connected together through the bottom electrode 216 . Reference numeral 209 is the second substrate, which is mainly used to form a sealed cavity structure through wafer level packaging, so as to protect the resonator disposed on the first substrate from external factors affecting its normal operation. Reference numerals 206 and 207 can be metal conductors such as gold, aluminum, copper, etc., which are essentially the same, except that the metal conductor 207 is a closed annular pattern located near the outer edge of the chip, which plays a sealing role; the metal conductor 206 It is the metal pattern that plays the role of electrical connection and is directly connected to a certain electrode of the resonator. Reference numeral 205 is a metal via hole passing through the second substrate 209 and connected to the pad 202 on the outer surface of the chip. The electrical signal of the resonator is conducted to the pad 202 through the bottom electrode 216, the metal conductor 206, and the metal via 205, and then connected to the external carrier board carrying the chip through gold wire bonding wires or flip-chip solder balls.

The two series resonators in Figure 2 will generate heat in the center of the resonator when passing a high power signal, but since air is a poor conductor of heat, silicon and all metals are generally good conductors of heat. , so the heat generated by the resonator will be mainly dissipated to the outside of the chip through the path indicated by the arrow in the figure.

FIG. 3 presents a schematic top view of a filter chip 300 (which can be considered to correspond to the filter chip 200 summarized in FIG. 2 ). Reference numeral 310 is a substrate; reference numeral 337 is a seal ring; reference numeral 336 is a via and substrate bonding area; reference numeral 344 is a top electrode pattern (thin solid line); reference numeral 346 is a bottom electrode pattern (thick solid line); reference numeral 348 is an air cavity (dotted line); reference numerals 311-314 are series resonators of series passages; reference numerals 321-323 are parallel resonators of parallel passages.

As shown in FIG. 2, in the above filter chip, when the chip is flip-chip mounted on the package carrier board, the heat of the series resonator is mainly dissipated through the second substrate, and the heat of the series resonator is mainly dissipated through the second substrate. When the encapsulation space is evacuated or filled with gas, it is difficult for the heat of the series resonator to reach the second substrate except for the metal via structure between the two substrates, which is not conducive to the heat dissipation of the series resonator.

SUMMARY OF THE INVENTION

The present invention is proposed to alleviate or solve at least one aspect of the above-mentioned problems using the prior art.

The present invention provides a piezoelectric filter, comprising: a first substrate; a second substrate opposite to the first substrate; a series resonator branch with a plurality of series resonators; a plurality of parallel resonator branches, each The two parallel resonator branches have parallel resonators, and the series resonators and the parallel resonators are arranged on the first substrate; the heat dissipation unit is arranged between two adjacent series resonators, forming The heat of at least one of the adjacent series resonators is conducted to the heat conduction path of the second substrate.

Optionally, the heat dissipation unit includes a first heat conduction part and a second heat conduction part, the first heat conduction part is thermally connected with at least one of the two adjacent series resonators, and the second heat conduction part is connected to the second heat conduction part. The first thermally conductive portion is thermally connected and adapted to conduct heat to the second substrate. Further optionally, the first heat conduction portion is thermally connected to the first substrate.

Optionally, the heat dissipation unit includes a second heat conduction portion, the second heat conduction portion is thermally connected to at least one of the two adjacent series resonators, and is adapted to conduct heat to the second heat conduction portion. base. Further optionally, the second heat conduction portion is thermally connected to the first substrate.

Optionally, the heat dissipation unit further includes a third heat conduction part disposed on a surface of the second base opposite to the first base, and the third heat conduction part is thermally connected to both the second heat conduction part and the second base. Optionally, the third heat conduction part includes a heat conduction pattern or a heat conduction layer.

Optionally, the two adjacent series resonators share a bottom electrode, and a portion of the shared bottom electrode between the piezoelectric layers of the two adjacent series resonators constitutes the first heat conduction part; or The two adjacent series resonators share a bottom electrode, and the first thermally conductive portion is thermally connected to a portion of the common bottom electrode between the piezoelectric layers of the two adjacent series resonators.

Optionally, the two adjacent series resonators are spaced apart from each other; and the top electrode of at least one of the two adjacent series resonators is thermally connected to the first heat conduction portion.

Optionally, the two adjacent series resonators are spaced apart from each other; the bottom electrode of at least one of the two adjacent series resonators is thermally connected to the first heat conduction part.

Optionally, the piezoelectric filter includes a sealing ring; at least one resonator is disposed adjacent to the sealing ring, and a bottom electrode of at least one of the at least one resonator extends toward the sealing ring to seal with the sealing ring. Ring thermal connection.

According to another aspect of the embodiments of the present invention, there is provided an electronic device having the above-mentioned piezoelectric filter.

Description of drawings

These and other features and advantages of the various disclosed embodiments of the present invention may be better understood by the following description and accompanying drawings, in which like reference numerals refer to like parts throughout, wherein:

1 is a schematic circuit diagram of a filter in the prior art;

2 is a schematic cross-sectional view of a filter chip in the prior art;

FIG. 3 is a schematic top view of the filter chip corresponding to FIG. 2;

4a is a schematic cross-sectional view of a filter chip according to an exemplary embodiment of the present invention, and FIG. 4b is a schematic view of a variant embodiment of FIG. 4a;

FIG. 5 is a schematic top view of the filter chip corresponding to FIG. 4a according to an exemplary embodiment of the present invention;

6 is a schematic cross-sectional view of a filter chip according to an exemplary embodiment of the present invention;

FIG. 7 is a schematic top view of the filter chip corresponding to FIG. 6 according to an exemplary embodiment of the present invention;

8 is a schematic top view of a filter chip according to an exemplary embodiment of the present invention, wherein only the thermal connection between the parallel resonator and the seal ring is shown;

FIG. 9 is a schematic cross-sectional view of the filter chip corresponding to FIG. 8 according to an exemplary embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals refer to the same or similar parts. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention, and should not be construed as a limitation of the present invention.

FIG. 4a is a schematic cross-sectional view of a filter chip 400 according to an exemplary embodiment of the present invention, and FIG. 4b is a schematic view of a modified embodiment of FIG. 4a. The difference between the embodiment shown in FIG. 4b and FIG. 4a is that, in FIG. 4b, the bottom electrodes of two adjacent series resonators are arranged separately, and the heat dissipation components corresponding to the reference numeral 432 are respectively connected to the bottom electrodes of the two resonators. The electrodes are thermally connected, and are also directly thermally connected to the first substrate. FIG. 5 is a schematic top view of a filter chip 500 corresponding to FIG. 4a according to an exemplary embodiment of the present invention.

In the present invention, the last two digits of the reference numerals in Figures 2-9 are the same, indicating that the two are the same or similar components or structures.

As shown in Figures 4a and 4b, reference numeral 432 is a bond added above the bottom electrode of the intermediate connection after the two series resonators (in Figure 5, corresponding to series resonators 512 and 513) are pulled apart area, the bonding area 432 is simultaneously connected to the metal layer 430 on the second substrate 409 for heat dissipation; the metal layer 430 can also be omitted. Since the thermal resistance of metal is small, the larger the area of the metal layer, the easier it is to help the device to dissipate heat.

Schematic heat flow diagrams are shown in Figures 4a and 4b. Since the device is flip-chip mounted on the underlying package carrier, the upper surface of the second substrate 409 is connected to the metal of the package carrier through solder balls, while The lower surface is in contact with the plastic encapsulation resin material used for protection. Since the thermal resistance of the metal is much smaller than that of the plastic encapsulation material, the heat of the device is mainly dissipated into the encapsulation carrier through the second substrate 409, thus connecting the two substrates. Metal becomes the main heat dissipation path.

Under the premise of not affecting the electrical performance of the device, this patent can effectively dissipate the heat generated by the series resonator under high power input to the second substrate by adding a similar heat dissipation path in the area where there is no bonding metal, so that it can effectively distributed to the package carrier.

FIG. 5 shows the metal pattern and bonding area 530 for heat dissipation, which can effectively reduce the temperature of the two adjacent series resonators 512 and 513, thereby increasing the power capacity of the filter. Shown in FIG. 5 are series resonators 511-514, parallel resonators 521-523, and metal pattern 530 for heat dissipation.

6 is a schematic cross-sectional view of a filter chip 600 according to an exemplary embodiment of the present invention, and FIG. 7 is a schematic top view of the filter chip 700 corresponding to FIG. 6 according to an exemplary embodiment of the present invention.

As shown in FIG. 6, the reference numeral 632 is to add a bonding area (heat dissipation part) above the bottom electrode connected in the middle after the two series resonators (in FIG. 7, corresponding to the resonators 713 and 714) are pulled apart. , which is simultaneously connected to the metal pattern 630 for heat dissipation on the second substrate; the difference from FIG. 4a and FIG. 4b is that the two series resonators originally connected through the top electrode are pulled away, and the top electrode Connected to a heat dissipation structure 632 .

As shown in FIG. 7 , the added heat dissipation structure can effectively reduce the temperature of the two series resonators 713 and 714 , thereby increasing the power capacity of the filter. Shown in FIG. 7 are series resonators 711-714, parallel resonators 721-723, and metal pattern 730 for heat dissipation.

Based on the above, the present invention proposes a filter, including:

the first substrate 410 or 610;

a second substrate 409 or 609 opposite to the first substrate;

a series resonator branch (see eg Fig. 1) having a plurality of series resonators (see eg 511-514 in Fig. 5, 711-714 in Fig. 7);

Multiple parallel resonator branches (see eg Figure 1), each parallel resonator branch having parallel resonators (eg see 521-523 in Figure 5, 721-723 in Figure 7), series resonators and parallel the resonator is arranged on the first substrate;

a heat dissipation unit, the heat dissipation unit is arranged between two adjacent series resonators (for example, between 512 and 513 in FIG. 5 and 713 and 714 in FIG. 7 ), forming a The heat of at least one of the devices is conducted to the heat conduction path of the second substrate 409 .

Referring to FIGS. 4a and 4b, in an exemplary embodiment, the heat dissipation unit includes a first heat conduction part (a part of the common bottom electrode 416 in FIG. 4a) and a second heat conduction part 432, the first heat conduction part and the At least one of the two adjacent series resonators is thermally connected, and the second thermally conductive portion 432 is thermally connected to the first thermally conductive portion and is adapted to conduct heat to the second substrate 409 . In FIG. 4a, the two adjacent series resonators share a bottom electrode, and the portion of the common bottom electrode between the piezoelectric layers of the two adjacent series resonators constitutes the first heat conduction portion. Although not shown, in FIG. 4a, the first heat conduction part can also be directly thermally connected to the common bottom electrode, that is, the first heat conduction part and the common bottom electrode are at the voltage of the two adjacent series resonators. Partial thermal connection between electrical layers.

In Figures 4a and 4b, the second thermally conductive portion 432 is thermally connected to the bottom electrodes of the two series resonators at the same time.

In Figures 4a and 4b, the component referenced 430 corresponds to the third heat conducting portion. Although not shown, as described above, the third heat conduction part may not be provided, as long as the second heat conduction part is thermally connected to the second substrate 409.

Although not shown, the heat dissipating unit may also include only one thermally conductive member that is directly thermally connected to the corresponding series resonator and directly thermally connected to the second substrate. Further, the one thermally conductive member may also be thermally connected to the first substrate at the same time, for example, in the form of FIG. 4b with the third thermally conductive member 430 removed and the second thermally conductive member 432 thermally connected to the second substrate.

As shown in FIG. 6 , two adjacent series resonators are spaced apart from each other; the top electrode of at least one of the two adjacent series resonators is thermally connected to the first heat conduction portion.

Referring to FIG. 4b, two adjacent series resonators are spaced apart from each other, and in the case where the part indicated by reference numeral 432 is used as the first heat conduction part, the bottom electrode of at least one of the two adjacent series resonators may be thermally connected to the first heat conducting portion.

Based on the technical solution of the present invention, the heat of the series connector is guided to the second substrate through a specially arranged heat dissipation unit, which effectively enhances the heat dissipation of the filter.

FIG. 8 is a schematic top view of a filter chip 800 according to an exemplary embodiment of the present invention, in which only the thermal connection between the parallel resonator and the seal ring is shown; FIG. 9 is an exemplary embodiment of the present invention A schematic cross-sectional view of the filter chip 900 corresponding to FIG. 8 according to the embodiment.

In FIG. 8, series resonators 811-814 and parallel resonators 821-823 provided on the substrate 810 are shown. The hatched portion in FIG. 8 constitutes an additionally provided heat dissipation portion. As shown in FIG. 8 , the bottom electrodes of the parallel resonators 822 and 823 near the series resonator 814 with a relatively high operating temperature are connected to the sealing ring 837 to form the heat dissipation part, so that the principle structure of the circuit is not changed. The performance of the filter is also not affected, but the temperature of the parallel resonators 822 and 823 can be effectively reduced, thereby providing a better heat dissipation environment for the series resonator 814 with a higher temperature and improving the power capacity of the filter.

As shown in FIG. 9 , the parallel resonators 922 and 923 are disposed near the series resonator 914 , and it can be seen that the bottom electrodes of the parallel resonators 922 and 923 both extend below the sealing ring 937 to form a thermal connection with the sealing ring 937 .

It should be pointed out that although the bottom electrode of the parallel resonator extends below the sealing ring to form a thermal connection with the sealing ring as an example for illustration in FIGS. 8 and 9, the bottom electrode of the series resonator adjacent to the sealing ring is also It may extend below the sealing ring to form a thermal connection with the sealing ring.

Based on the technical solutions shown in Fig. 8 and Fig. 9, the sealing ring of the filter can be effectively used as an integral part of the heat dissipation path.

It should be specially pointed out that, the solution in FIG. 8 or FIG. 9 can be implemented alone or in combination with the solutions in FIGS. 4a, 4b-7.

Embodiments of the present invention also relate to an electronic device including the above-mentioned radio frequency piezoelectric multiplexer. It should be pointed out that the electronic equipment here includes but is not limited to intermediate products such as RF front-end, filter and amplifier modules, and terminal products such as mobile phones, WIFI, and drones.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is determined by It is defined by the appended claims and their equivalents.

Claims (12)

1. A piezoelectric filter comprising:

a first substrate;

a second substrate opposite the first substrate;

a series resonator arm having a plurality of series resonators; and

a plurality of parallel resonator arms, each parallel resonator arm having a parallel resonator,

wherein:

the series resonator and the parallel resonator are arranged on the first substrate;

the piezoelectric filter further includes a heat dissipation unit disposed between two adjacent series resonators forming a heat conduction path that conducts heat from at least one of the two adjacent series resonators to the second substrate.

2. The piezoelectric filter of claim 1, wherein:

the heat dissipation unit includes a first heat conductive portion thermally connected to at least one of the two adjacent series resonators, and a second heat conductive portion thermally connected to the first heat conductive portion and adapted to conduct heat to the second substrate.

3. The piezoelectric filter of claim 2, wherein:

the first heat conduction portion is in thermal connection with the first substrate.

4. The piezoelectric filter of claim 1, wherein:

the heat dissipating unit includes a second heat conductive portion thermally connected to at least one of the two adjacent series resonators and adapted to conduct heat to the second substrate.

5. The piezoelectric filter of claim 4, wherein:

the second heat conduction portion is thermally connected to the first substrate.

6. The piezoelectric filter of any one of claims 2-5, wherein:

the heat dissipation unit further comprises a third heat conduction part arranged on the surface, opposite to the first substrate, of the second substrate, and the third heat conduction part is in thermal connection with the second heat conduction part and the second substrate.

7. The piezoelectric filter of claim 6, wherein:

the third heat conductive portion includes a heat conductive pattern or a heat conductive layer.

8. The piezoelectric filter of any one of claims 2-7, wherein:

the two adjacent series resonators share a bottom electrode, and a portion of the shared bottom electrode between the piezoelectric layers of the two adjacent series resonators constitutes the first heat conduction section; or

The two adjacent series resonators share a bottom electrode, and the first thermally conductive section is thermally connected to a portion of the shared bottom electrode between the piezoelectric layers of the two adjacent series resonators.

9. The piezoelectric filter of any one of claims 2-7, wherein:

the two adjacent series resonators are spaced apart from each other;

the top electrode of at least one of the two adjacent series resonators is thermally connected to the first thermally conductive section.

10. The piezoelectric filter of any one of claims 2-7, wherein:

the two adjacent series resonators are spaced apart from each other;

the bottom electrode of at least one of the two adjacent series resonators is thermally connected to the first thermally conductive section.

11. The piezoelectric filter of any one of claims 1-10, wherein:

the piezoelectric filter includes a seal ring;

at least one resonator is disposed adjacent the confinement ring, and a bottom electrode of at least one of the at least one resonator extends toward the confinement ring to be thermally coupled to the confinement ring.

12. An electronic device having a piezoelectric filter according to any one of claims 1 to 11.

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