KR100550917B1 - Saw duplexer using pcb substrate - Google Patents

Abstract

The present invention relates to a SAW duplexer, the present invention comprises a SAW filter; An SAW filter mounting unit comprising at least one HTCC substrate stacked on the upper surface of the SAW filter, and having a first electrode electrically connected to the SAW filter on a rear surface thereof; And a matching circuit unit including a plurality of PCB substrates each having a second electrode in contact with the first electrode, a ground pattern, a matching circuit pattern for the SAW filter, and a third electrode for electrical connection with the outside. Provide a duplexer. According to the present invention, there is an effect of reducing the cost of the SAW duplexer and improve the quality and yield.

SAW duplexer, SAW filter, surface acoustic wave filter, matching, HTCC, LTCC, PCB

Description

SAW duplexer using PCB PCB {SAW DUPLEXER USING PCB SUBSTRATE}             

1 is a cross-sectional view showing the structure of a SAW duplexer manufactured using a conventional LTCC process.

2 is a cross-sectional view showing the structure of a SAW duplexer according to an embodiment of the present invention.

3 is a plan view showing a pattern of a PCB substrate according to an embodiment of the present invention.

4 is a cross-sectional view showing the structure of a SAW duplexer according to another embodiment of the present invention.

5 is a plan view showing a pattern of a PCB substrate according to another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

100, 200, 300: SAW filter 211: first HTCC substrate

212: second HTCC substrate 213: third HTCC substrate

311: fourth HTCC substrate 221, 321: first PCB substrate

222, 322: second PCB substrate 223, 323: third PCB substrate

The present invention relates to a SAW duplexer, and more particularly, a SAW filter is mounted on an element mounting substrate made of an HTCC substrate manufactured using an HTCC process, and a plurality of PCB substrates on which a ground and a matching circuit are printed are stacked on an upper surface thereof. The present invention relates to a SAW duplexer which reduces manufacturing cost and has excellent insertion loss characteristics by bonding a matching substrate and an element mounting substrate to electrically connect the SAW filter and the matching circuit.

In general, a duplexer is a component used in the front-end of a mobile communication device. The duplexer separates a transmission frequency and a reception frequency among various radio signals of the mobile communication device, and transmits the signal in a wide frequency band. It is the part that selects only the required frequency among the many mixed noise signals. The duplexer is generally connected to the bottom of the antenna to separate transmission and reception frequencies, passes only necessary signals during transmission and reception, and removes unnecessary signals. Until now, a monoblock type is commonly used as a dielectric filter. Increasingly light weight is being replaced by surface acoustic wave (SAW) duplexer. The SAW duplexer is manufactured in a form including a matching circuit implemented as a stripline to reduce the weight and weight of components. 1 shows a cross section of a conventional SAW duplexer.

Referring to FIG. 1, a conventional SAW duplexer includes a first ceramic substrate 111 having a matching circuit pattern formed on an upper surface thereof and an electrode for connecting to the outside thereof, and a second ceramic having an internal ground pattern formed on an upper surface thereof. A fourth ceramic substrate having a substrate 112, a third ceramic substrate 113 on which an SAW filter is mounted, and a first cavity formed in a predetermined area of the center, and an internal electrode electrically connected to an SAW filter on an upper surface thereof. A fifth ceramic substrate 115 having a central portion of a second cavity having a larger area than the first cavity so as to be connected to include a region of the first cavity, and the third ceramic substrate 113 in the cavity; A SAW filter 100 mounted on an upper surface and electrically connected to the internal electrode by a wire bonding method, and formed on an upper surface of the fifth ceramic substrate 115 to seal the cavity area to protect the SAW filter. A metallic lid 116 to be formed.

Such a SAW duplexer manufactures substrates by a low temperature co-fired ceramic (LTCC) method that can use Ag, Ag / Pd metal having excellent electrical conductivity as a pattern. The LTCC method is a technique of forming a substrate using a simultaneous firing method of ceramic and metal at a low temperature of about 800 to 1000 ° C. A glass and ceramic having a low melting point are mixed to form a green sheet having an appropriate dielectric constant, It is a method of forming a board | substrate after printing and laminating | stacking the electrically conductive paste which made copper the main raw material.

On the other hand, there is a high temperature co-fired ceramic (HTCC) method as a method in contrast to the LTCC method. The HTCC method is a technique for forming a substrate using a method of simultaneously firing a ceramic and a metal at a temperature of 1300 ° C or more. This HTCC process uses a process of firing at high temperature, so it is possible to use a metal having excellent electrical conductivity such as Ag, Ag / Pd but low melting point as a pattern. Therefore, since W, Mo, etc. are used as a metal for forming the internal pattern, it is difficult to use in the RF field because of poor electrical conductivity.

Therefore, the SAW duplexer used in the CDMA mobile communication device, etc. to manufacture the substrate using the LTCC method. However, the LTCC method has a problem of lowering the price competitiveness of the product by increasing the unit cost of the product because the material used for manufacturing is expensive. In addition, the LTCC method has a problem in that the firing process is difficult, the pattern is not easy to form, and a poor yield such as leakage loss through an interface occurs. In addition, since the conventional SAW duplexer is manufactured by all the substrates, matching circuits, etc. through the LTCC method, there is a problem that can not determine whether each SAW filter chip or matching circuit unit is defective.

Therefore, there is a need in the art for a SAW duplexer that can reduce product cost, improve yield, and at the same time, can easily check whether the SAW filter chip and the matching circuit unit are defective.

The present invention has been made to solve the above-described problems, an object of the present invention, the SAW filter mounting portion made of a HTCC substrate and mounts the SAW filter on the upper surface, and a matching circuit portion laminated a PCB substrate formed with a matching circuit pattern After separately manufacturing each, by electrically bonding the SAW filter mounting portion and the matching circuit portion, it is possible to reduce the cost of the product, improve the yield, and at the same time can easily check whether each of the SAW filter chip and the matching circuit portion defective To provide a SAW duplexer.

The present invention to achieve the above object,

SAW filter;
An SAW filter mounting unit comprising at least one HTCC substrate stacked on the upper surface of the SAW filter, and having a first electrode electrically connected to the SAW filter on a rear surface thereof; And
A SAW duplexer including a plurality of PCB substrates each having a second electrode in contact with the first electrode, a ground pattern, a matching circuit pattern for the SAW filter, and a third electrode for electrical connection to the outside are stacked. To provide.

Preferably, the SAW filter mounting part and the matching circuit part are joined by a solder joint method. In addition, the matching circuit unit, a third electrode for the electrical connection to the outside is formed on the back, the first PCB substrate with a matching circuit pattern for the SAW filter is formed on the upper surface, and laminated on the upper surface of the first PCB substrate A second PCB substrate having an internal ground pattern formed on an upper surface thereof and a third PCB substrate stacked on an upper surface of the second PCB substrate and having a second electrode contacting the first electrode formed on an upper surface thereof may be included. The matching circuit may be an inductor implemented in a spiral pattern.

In one embodiment of the present invention, the SAW filter mounting portion, the first HTCC substrate having the first electrode formed on the back, the first HTCC substrate is laminated on the upper surface, a first cavity is formed in the center, the first A second HTCC substrate having an internal electrode for electrical connection with the SAW filter on an upper surface where the cavity is not formed, and a second cavity stacked on an upper surface of the second HTCC substrate, and wider than an area of the first cavity, are located at the center. A third HTCC substrate formed on the upper surface of the third HTCC substrate and a lead formed in the first cavity and the second cavity, and the SAW filter includes a position where the first cavity is formed on the upper surface of the first HTCC substrate. The SAW filter may be mounted in a wire bonding manner with the internal electrode, and the internal electrode may be electrically connected with the first electrode through a via hole.

In this case, the sum of the thicknesses of the first HTCC substrate and the second HTCC substrate is preferably 0.4 mm to 0.5 mm.

Further, in another embodiment of the present invention, the SAW filter mounting unit has an internal electrode for mounting the SAW filter on a top surface by flip chip bonding, and the first electrode contacting the matching circuit unit is formed on a rear surface of the SAW filter mounting unit. It may include a fourth HTCC substrate formed, wherein the thickness of the fourth HTCC substrate is preferably 0.2mm to 0.35mm.

Hereinafter, various embodiments of the SAW duplexer according to the present invention will be described in detail with reference to the accompanying drawings.

The embodiment of the present invention shown in Figure 2 is a form in which the SAW filter is connected to the package by a wire bonding method, Figure 2a shows a cross section of the SAW filter mounting portion of the SAW duplexer according to an embodiment of the present invention, 2b shows a matching circuit section, and FIG. 2c shows a cross section of a SAW duplexer completed by joining the SAW filter mounting section and the matching circuit section. The SAW duplexer according to the present invention is completed by separately fabricating the SAW filter mounting portion shown in FIG. 2A and the matching circuit portion shown in FIG. 2B and then bonding them.

First, referring to FIG. 2A, the SAW filter mounting part is stacked on a first ceramic substrate 211 having a first electrode formed on a rear surface thereof, an upper surface of the first ceramic substrate 211, and a first cavity formed at a central portion thereof. And a second ceramic substrate 212 having an internal electrode for electrical connection with the SAW filter on an upper surface where the first cavity is not formed, and stacked on an upper surface of the second ceramic substrate 212. A second cavity wider than an area of the third ceramic substrate 213 is formed in the center and the upper surface of the third ceramic substrate 213, and includes a lead 116 for sealing the first cavity and the second cavity. . The SAW filter 200 is mounted at a position where the first cavity is formed on an upper surface of the first ceramic substrate 211, the SAW filter 200 is connected to the internal electrode by a wire bonding method, and the internal electrode is the The first electrode is electrically connected to the via hole.

The ceramic substrates 211 to 213 may be manufactured using an HTCC process having a low manufacturing cost. Since an important pattern of electrical characteristics such as a matching circuit is not formed inside the ceramic substrate, it is not necessary to use a substrate using an LTCC process having good electrical characteristics but an expensive metal pattern.

In addition, in order to reduce the size of the SAW duplexer, the sum of the thicknesses of the first ceramic substrate 111 and the second ceramic substrate 115 is preferably 0.4 mm to 0.5 mm.

The first electrode is for electrically connecting with a matching circuit unit formed at a lower side thereof, and the first electrode is in contact with a corresponding electrode formed on an upper surface of the matching circuit unit.

The SAW filter is mounted on a portion where the first cavity of the upper surface of the first ceramic substrate 211 is formed and connected to the internal electrode formed on the upper surface of the second ceramic substrate 212 by wire bonding. In addition, the internal electrode is electrically connected to the first electrode. The electrical connection between the internal electrode and the first electrode is preferably formed by forming via holes in the first and second ceramic substrates 211 and 212 to minimize the connection distance.

The lead 214 is formed of a metallic material on an upper surface of the third ceramic substrate 213 to seal the first and second cavities. This serves to protect the SAW filter from disturbances.

Next, referring to FIG. 2B, a matching circuit unit is manufactured by stacking a plurality of PCB substrates separately from the SAW filter mounting unit described with reference to FIG. 2A. The matching circuit unit includes a first PCB substrate 221 having a third electrode formed thereon for electrical connection to the outside on a rear surface thereof, and a matching circuit pattern for the SAW filter formed on an upper surface thereof, and the first PCB substrate 221. A third PCB stacked on an upper surface, and having an internal ground pattern formed on an upper surface thereof, and a third PCB stacked on an upper surface of the second PCB substrate 222 and formed with a second electrode contacting the first electrode on an upper surface thereof; It comprises a substrate 223.

Since the matching circuit pattern formed on the upper surface of the first PCB substrate 221 has a better plating state than the pattern formed on the ceramic substrate by the LTCC process, the loss of the high frequency signal may be reduced by improving the insertion loss characteristic. The use of PBC substrates also facilitates future compositing with other RF components such as power amplifier modules, SAW filters and RF switches.

The SAW filter mounting part and the matching circuit part manufactured as shown in FIGS. 2A and 2B may be bonded to contact the first electrode and the second electrode in a general solder bonding method. 2C illustrates a SAW duplexer completed by joining the SAW filter mounting unit and the matching circuit unit.

As such, in the related art, a ceramic substrate manufactured using the LTCC process is used to use a metal having good electrical characteristics as a pattern. Conventionally, the characteristics of the SAW duplexer is improved by configuring a matching circuit using a metal pattern having good electrical characteristics using the LTCC process, but there is a problem in that the manufacturing cost increases due to a complicated LTCC process and expensive materials. However, in the present invention, only a part of electrodes are formed in the SAW filter mounting portion in which the ceramic substrate is used, and the matching circuit in which the electrical characteristics are important is implemented using the PCB substrate, thus eliminating the need for an expensive LTCC process. Therefore, the ceramic substrate used in the SAW filter mounting portion can be manufactured using an HTCC process that is less expensive. This reduces the cost of the product.

FIG. 3 illustrates an example of each PCB substrate pattern that forms a matching circuit part connected to the SAW filter mounting part mounting the SAW filter by the wire bonding method described above. FIG. 3A illustrates a pattern formed on an upper surface of the third PCB substrate, and the patterns come into contact with a first electrode on a rear surface of the SAW filter mounting portion which is in contact with the upper portion. 3B illustrates an internal ground pattern formed on the top surface of the second PCB substrate. FIG. 3C illustrates an example of a matching circuit pattern formed on an upper surface of the first PCB substrate in a meander shape. Instead of such a meander shape, a matching circuit pattern having a spiral shape shown in FIG. 5C may be used. Since the meander shape of the spiral matching circuit pattern may reduce the insertion loss by reducing the length of the pattern than the matching circuit pattern, it is more preferable to form the matching circuit pattern of the spiral shape. 3D illustrates a pattern of a third electrode formed on a rear surface of the first PCB substrate, and a terminal is formed to receive a signal from the outside and output a signal passed through the SAW duplexer. That is, the high frequency signal received from the antenna is inputted to the antenna terminal connected to the antenna and passed through the SAW duplexer, and then outputted to the RX terminal connected to the LNA, and the transmitted high frequency signal is inputted to the TX terminal connected to the PAM and passed through the SAW duplexer. It is then output to the antenna terminal.

FIG. 4 illustrates another embodiment of the present invention. In the embodiment described with reference to FIG. 2, the SAW filter mounting unit uses a wire bonding method, whereas the embodiment illustrated in FIG. 4 is a flip chip. Bonding method is used. First, FIG. 4A illustrates a SAW filter mounting unit according to another embodiment of the present invention, wherein the SAW filter mounting unit has an internal electrode for mounting the SAW filter on a top surface by flip chip bonding, and the matching on the back surface. And a fourth ceramic substrate 311 having a first electrode in contact with the circuit portion.

The fourth ceramic substrate 311 is preferably a ceramic substrate manufactured through the HTCC process. The SAW filter 300 is mounted on the upper surface of the fourth ceramic substrate 311 so as to be electrically connected to the internal electrode through the bump by flip chip bonding. The internal electrode may be electrically connected to the first electrode through a via hole formed in the fourth ceramic substrate 311. After the SAW filter is mounted on the fourth ceramic substrate 311 by flip chip bonding, a protective film 312 made of metal is formed on the top and side surfaces of the SAW filter and the top surface of the fourth ceramic substrate. The passivation layer 312 is most preferably made of gold (Au), and the passivation layer 312 is connected to an internal ground pattern in a matching circuit portion formed at a lower portion thereof, and serves as an electrical ground, thereby preventing the protection layer 312 from the external electric or magnetic field. It protects the SAW filter.

Next, referring to FIG. 4B, similar to FIG. 2B, the matching circuit unit is manufactured by stacking a plurality of PCB substrates separately from the SAW filter mounting unit described with reference to FIG. 4A. The matching circuit unit includes a first PCB substrate 321 having a third electrode formed on the rear thereof for electrical connection to the outside, and a matching circuit pattern for the SAW filter formed on an upper surface thereof, and the first PCB substrate 321. A third PCB stacked on an upper surface, and having an internal ground pattern formed on an upper surface thereof, and a third PCB stacked on an upper surface of the second PCB substrate 322, and formed with a second electrode in contact with the first electrode on an upper surface thereof; It comprises a substrate 323.

Since the matching circuit pattern formed on the upper surface of the first PCB substrate 321 has a better plating state than the pattern formed on the ceramic substrate by the LTCC process, the loss of the high frequency signal may be reduced by improving the insertion loss characteristic. The use of a PBC board also facilitates future compositing with other RF components such as power amplifier modules, SAW filters and RF switches.

The SAW filter mounting part and the matching circuit part manufactured as shown in FIGS. 4A and 4B are preferably bonded to contact the first electrode and the second electrode in a general solder bonding method. 4C illustrates a SAW duplexer completed by joining the SAW filter mounting unit and the matching circuit unit.

FIG. 5 shows an example of each PCB substrate pattern constituting a matching circuit unit connected to the SAW filter mounting unit mounting the SAW filter by the flip chip bonding method described above. FIG. 5A illustrates a pattern formed on an upper surface of the third PCB substrate, and the patterns come into contact with a first electrode on a rear surface of the SAW filter mounting portion which is in contact with the upper portion. FIG. 5B illustrates an internal ground pattern formed on the top surface of the second PCB substrate. 5C illustrates an example of a pattern formed in a spiral shape with a matching circuit pattern formed on an upper surface of the first PCB substrate. Instead of such a helical shape, a matching circuit pattern having a meander shape shown in FIG. 3C may be used. However, the matching circuit pattern of the helical shape has an insertion loss because the meander shape reduces the length of the pattern than the matching circuit pattern. Since it can be reduced, it is more preferable to form the spiral matching circuit pattern. FIG. 5D illustrates a pattern of a third electrode formed on a rear surface of the first PCB substrate. A terminal is formed to receive a signal from the outside and output a signal passing through the SAW duplexer. That is, the high frequency signal received from the antenna is inputted to the antenna terminal connected to the antenna and passed through the SAW duplexer, and then outputted to the RX terminal connected to the LNA, and the transmitted high frequency signal is inputted to the TX terminal connected to the PAM and passed through the SAW duplexer. It is then output to the antenna terminal.

As described above, the SAW duplexer according to the present invention does not form a matching circuit on the ceramic substrate, thereby reducing the cost of the product because it does not use the LTCC process, which has good electrical characteristics but is expensive. In addition, since the matching circuit is implemented using a PCB plate with a good plating state, insertion loss is reduced, thereby improving product quality. In addition, by separately mounting the mounting portion on which the SAW filter is mounted and the matching circuit portion on which the matching circuit is formed, it is possible to identify each defect in advance, thereby improving the yield of the product.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims, and various forms of substitution, modification, and within the scope not departing from the technical spirit of the present invention described in the claims. It will be apparent to those skilled in the art that changes are possible.

According to the present invention described above, since the matching circuit is not formed on the ceramic substrate, it is possible to reduce the cost of the product because it does not use the LTCC process, which has good electrical characteristics but is expensive. In addition, according to the present invention, since the matching circuit used for the SAW duplexer is implemented using a PCB plate with a good plating state, insertion loss is reduced, thereby improving the product quality. Furthermore, by separately manufacturing the mounting portion on which the SAW filter is mounted and the matching circuit portion on which the matching circuit is formed in the SAW duplexer, it is possible to identify each defect in advance, thereby improving the yield of the product.

Claims (9)

SAW filter; An SAW filter mounting unit comprising at least one HTCC substrate stacked on the upper surface of the SAW filter, and having a first electrode electrically connected to the SAW filter on a rear surface thereof; And A SAW duplexer including a plurality of PCB substrates each having a second electrode in contact with the first electrode, a ground pattern, a matching circuit pattern for the SAW filter, and a third electrode for electrical connection to the outside are stacked. . The method of claim 1, The SAW filter mounting part and the matching circuit part are bonded by a solder joint method. delete The method of claim 1, wherein the SAW filter mounting portion, A first HTCC substrate having the first electrode formed on a rear surface thereof; A second HTCC substrate stacked on an upper surface of the first HTCC substrate, having a first cavity formed in a central portion thereof, and having an internal electrode for electrical connection with the SAW filter on an upper surface on which the first cavity is not formed; A third HTCC substrate stacked on an upper surface of the second HTCC substrate and having a second cavity wider than an area of the first cavity at a central portion thereof; And A lead formed on an upper surface of the third HTCC substrate, the lid sealing the first cavity and the second cavity, and the SAW filter is mounted at a position where the first cavity is formed on an upper surface of the first HTCC substrate, A filter is connected to the inner electrode by a wire bonding method, and the inner electrode is electrically connected to the first electrode through a via hole. The method of claim 4, wherein The sum of the thicknesses of the first HTCC substrate and the second HTCC substrate is a SAW duplexer, characterized in that 0.4mm to 0.5mm. The method of claim 1, wherein the SAW filter mounting portion, And a fourth HTCC substrate having an internal electrode formed thereon for mounting the SAW filter on a top surface thereof and having the first electrode contacting the matching circuit unit on a rear surface thereof. The method of claim 6, wherein the thickness of the fourth HTCC substrate, SAW duplexer, characterized in that 0.2mm to 0.35mm. The method of claim 1, wherein the matching circuit unit, A first PCB substrate having a third electrode formed on the rear surface for electrical connection with the outside and a matching circuit pattern for the SAW filter formed on the top surface; A second PCB substrate stacked on an upper surface of the first PCB substrate and having an inner ground pattern formed on the upper surface thereof; And And a third PCB substrate stacked on an upper surface of the second PCB substrate and having a second electrode on the upper surface thereof in contact with the first electrode. The method of claim 8, The matching circuit is a SAW duplexer, characterized in that the inductor implemented in a spiral pattern (spiral).

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