JP2003347444A - High frequency power amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency power amplifier exhibiting high stability. <P>SOLUTION: In packaging of the high frequency power amplifier, the claw 15 of a metallic base 13 engages with the hole 17 of a metallic cover 11 and a recess 18 having a through hole 19 is provided at a specified position of the sidewall material 16 of the metallic cover 11. The metallic cover 11 and the metallic base 13 are bonded through that through hole 19 by reflow soldering. The metallic base 13 is provided with a stretching part which is bonded to a specified part of a circuit board by reflow soldering. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high frequency power amplifier, and more particularly, to a high stability high frequency power amplifier.

[0002]

2. Description of the Related Art A high-frequency power amplifier used for a base station of a mobile phone in a mobile communication network has a function of amplifying and outputting a weak signal transmitted from a mobile phone as a mobile communication device. Is required. The frequency band of such a high-frequency power amplifier is 0.8 to 2.1 GHz, and most of the conventional modules are configured as so-called hybrid ICs in which a plurality of amplifying devices and passive devices are integrated. And housed in a package as shown in FIG.

FIG. 5 is a cross-sectional view showing an example of a connection structure between a metal base and a metal lid of a conventional high-frequency power amplifier.
It has a plurality (at least three) of connection pieces 502a extending substantially parallel to the side plate portion 503a of the metal lid 503. In this figure, only the integral connection piece 502a is shown. Each of the connecting pieces 502a is formed with a projection 503b that protrudes outward by "striking processing" or the like. Also, the side plate portion 503a of the metal lid 503
Are formed with connection holes 503b so as to face the projections 502b of the connection pieces 502a.

When fixing the metal cover 503 to the metal base 502, the metal cover 503 is placed over the metal base 502, and the projections 502b of the connection pieces 502a are connected to the connection holes 503b of the side plate portion 503a. Fit into Thus, the metal base 502 and the metal lid 50 are
3 are electrically connected at the same time as they are fixed to each other.

FIG. 6 is a cross-sectional view showing another example of a connection structure between a metal base and a metal lid of a conventional high-frequency power amplifier. The metal base 602 of the high-frequency power amplifier 601 is
A plurality of (at least three) recesses 602a are provided on the bottom side. In addition, a supporting piece 603b projecting inwardly by a “bending process” or the like is provided on the side plate portion 603a of the metal lid body 603 in each of the recesses 6 of the metal base 602.
A plurality is formed so as to oppose 02a.

When the metal cover 603 is fixed to the metal base 602, the metal cover 603 is placed over the metal base 602, and each recess 602a of the metal base 602 and each support of the cover 603 are fixed. The pieces 602b are engaged with each other. Thus, the metal base 602 and the metal lid 603 are mechanically fixed to each other and simultaneously electrically connected.

[0007]

However, in the structure of the high-frequency power amplifier as shown in FIGS. 5 and 6, the contact area between the projection and the connection hole or between the depression and the support piece depends on the processing accuracy of the package. If the processing accuracy of the package is low, for example, the potential of the metal lid increases, or the electrical contact between the metal base and the metal lid becomes unstable, and the metal lid There was a problem that the body was insufficiently grounded.

When the grounding of the metal lid of the high-frequency power amplifier becomes insufficient, the output signal of the power amplifier goes around to the input terminal via the metal lid, and oscillation and spurious at the output of the high-frequency power amplifier occur. Resulting in. This phenomenon becomes more conspicuous as the frequency of the high-frequency signal input to the high-frequency power amplifier increases, and is particularly conspicuous in a band whose frequency exceeds 2 GHz.

Further, when the processing accuracy of the package is low, the mechanical fixing between the metal base and the metal lid is incomplete, so that the module housed in the package is affected by external vibrations and the like. There is also a problem that the electrical contact becomes incomplete and electrical contact becomes incomplete, and in extreme cases, self-oscillation occurs. In particular, if the signal output from one base station increases with the spread of mobile phones, the current flowing through the amplifying device inside the high-frequency power amplifier increases, so that such a metal base and the metal lid are unstable. Mechanical locking also results in impaired stable operation of the high frequency power amplifier.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a high-frequency power amplifier having high stability.

[0011]

According to the present invention, in order to achieve the above object, the invention according to claim 1 comprises a grounded metal base and a metal base on which a high-frequency circuit element is mounted. A high frequency power amplifier comprising a circuit board mounted to be grounded and a metal lid fixed to the metal base so as to cover the circuit board, wherein a part of an edge of the metal base is provided. Has a side surface portion having an engaging means, a hole is provided in a part of the side surface portion of the metal lid, and the engaging means engages with the hole,
The metal lid and the metal base are bonded and fixed by reflow soldering.

The invention described in claim 2 is the first invention.
In the high-frequency power amplifier described in the above, a concave portion having a through hole is provided at a predetermined position on the side surface portion of the metal lid, and the inside of the side surface portion of the metal lid body provided with the concave portion and the metal It is characterized in that the side surface of the base made of a resin is bonded and fixed by reflow soldering.

The invention described in claim 3 is the first invention.
3. The high-frequency power amplifier according to claim 2, wherein the engaging means is a claw processed, and an engaging portion between the claw and the hole is adhered and fixed by reflow soldering.

The invention described in claim 4 is the first invention.
4. The high-frequency power amplifier according to any one of to
The metal cover has an overhang portion, and the overhang portion and a predetermined portion of the circuit board are bonded and fixed by reflow soldering.

The invention described in claim 5 is the first invention.
5. The high-frequency power amplifier according to any one of items 1 to 4, wherein the metal lid is plated with Au or Ni.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the packaging of the high-frequency power amplifier of the present invention. This high-frequency power amplifier is composed of a metal lid 11, a substrate 12, and a metal base 13. I have.

The substrate 12 is made of a material such as PCB or ceramic, and the entire surface on the metal base 13 side is a ground plane. Further, an opening 14 for mounting an amplification device or the like is provided with a predetermined area. A number is provided. A plurality of edge clip-type lead pins 20 are provided in a part of the edge of the substrate 12 to enable electrical connection with an external device. Note that the substrate 12 may be a so-called multilayer substrate, and wiring of an amplification device or the like may be patterned in an intermediate layer.

The metal base 13 has side portions 14a, 1
4b is provided, and a side wall member 16 having a hole 17 is provided at a position corresponding to the metal lid 11, so that the hole 17 and the claw 15 of the metal base 13 are engaged with each other. ing. A recess 18 having a through hole 19 is provided near the center of the side wall member 16 of the metal lid 11.

In the high-frequency power amplifier according to the present invention, the metal cover 11 and the metal base 13 are mechanically fixed to each other by the hole 17 of the metal cover 11 and the corresponding metal base 13.
In addition to the fitting with the claw 15, a hole (not shown) corresponding to the side surface portion 14 a of the metal base 13 and the through hole 1 are formed.
The metal lid 11 is soldered to the metal base 13 through both openings 9.

Hereinafter, the structures of the metal base and the metal lid will be described in more detail.

FIG. 2 is a view for explaining in detail the structure of the metal base shown in FIG. 1. FIG. 2 (a) is a top view of the metal base, and FIG. 2 (b) is a view of the metal base. FIG. 2C shows a side view and a state in which a metal base and a metal lid are fitted together.

The metal base 21 is made of, for example, copper, iron, Kovar, or the like so that it can be soldered to a metal lid.
It is made of a metal such as stainless steel. In the example shown in FIG.
Ni is plated. A substrate on which an amplification device or the like is modularized is mounted on the metal base 21, and a ground pattern provided on the back surface of the substrate and the metal base 21 are electrically connected.

At each of the longitudinal edges of the metal base 21, there are provided side portions 22a and 22b in which a part of the metal base 21 is bent, and these side portions 22a and 22b are provided.
Each of the predetermined positions of 22b is provided with a claw 23a, 23b, 23c of about 0.9 mm square which has been “leashed”. Each of these claws 23a, 23b and 23c is fitted into a square hole 26 of about 1 mm square provided in the metal lid 25 as shown in FIG. The metal base 21 is mechanically fixed. However, the claws 23 of the metal base 21 and the metal lid 2
5 is provided with a gap of about 0.1 mm in order to secure a margin for the fitting, so that the fitting between the claw 23 and the hole 26 alone makes the metal base 21 It is insufficient for mechanically fixing the metal lid.

In each of the short edges of the metal base 21, there are provided two notches 24a to 24d for mechanically connecting the high-frequency power amplifier to a substrate (not shown).
Are provided one by one.

FIG. 3 is a view for explaining in detail the structure of the metal lid shown in FIG. 1. FIG. 3 (a) is a top view and FIG.
(B) is one side view, and FIG. 3 (c) is the other side view.

The metal cover 31 is formed by cutting out a single metal plate and bending the metal plate. In the example shown in the figure, the metal cover 31 has a nickel white plate having a thickness of 0.25 mm. (Cu
/ Ni / Zn alloy) or stainless steel, the surface of which is plated with Ni or Au of about 5 μm. Further, from the side surface where the side wall member 32 is not provided, it is possible to protrude the edge clip type lead pin attached to the end of the substrate to the outside of the metal lid 31.

A hole 33 is provided at a position of the side wall member 32 corresponding to the side surface portion of the metal base.
3 and a metal base claw engage with each other.
In addition, near the center of the side wall member 32a having two holes,
A concave portion 34 having a diameter of about 3.5 mm and having a depth of about 0.1 mm is provided therein, and a through hole 35 having a diameter of 1.7 mm is formed substantially at the center of the concave portion 34. Recess 34
And the center of the through hole 35 does not coincide, and the center of the concave portion 34 is located below the center of the through hole 35. The opening of the through hole 35 and the side wall member 32 having one hole
Both the openings of the holes 33c provided in b are soldered to the metal base, so that the metal lid 31 and the metal base are securely fixed.

Since the recess 34 has a depression of about 0.1 mm, the gap between the inside of the recess 34 and the corresponding outside of the side surface of the metal base is about 0.1 mm or less. Therefore, when the solder is reflowed through the through hole 35 provided in the concave portion 34, the solder penetrates into the gap of about 0.1 mm or less, and good solder fixation becomes possible.

On the other hand, even if the solder is reflowed only through the through hole 35 without providing the recess 34, the solder does not easily permeate between the two members, and it is difficult to enhance the solder adhesiveness. It is. Further, since the center of the concave portion 34 is located below the center of the through hole 35, the solder bonding is performed at a position close to the base of the metal base, so that more stable fixing is ensured. Become.

The solder reflow is also performed from the opening of the hole 33c provided in the side wall member 32b having one hole. This hole 33c has a size of 1 mm ×
Since it is a rectangle of about 1.6 mm, there is always a place in contact with the metal base. Therefore, soldering is performed over a sufficiently narrow gap centered on the contact portion with the metal base by applying the paste solder inside the hole 33c and performing reflow.

In the above-described packaging method, the electric shielding property and the mechanical fixing are improved by fixing the metal lid to the metal base by soldering. A part of the lid body may be directly fixed to a part of the substrate by soldering.

FIGS. 4A and 4B are views for explaining the structure of the metal lid when such a packaging method is adopted. FIG. 4A is a top view, and FIG. A) AA '
FIG. The metal lid 41 and the metal base 43 are fixed by soldering in the same manner as in the above-described method, but projecting projections 42a and 42b are provided on both side surfaces of the metal lid 41. These overhangs 42
a and 42b are solder reflowed directly to the shield wiring on the substrate (not shown).

According to such a packaging method,
It becomes possible to further improve the electric shielding property and the fixed stability, and it is possible to ensure a further stable operation of the high-frequency power amplifier. In this method, the overhang portion 42
Since the a and 42b do not mechanically hold the high-frequency power amplifier, the size of the overhang portions 42a and 42b is sufficient to allow solder reflow and ensure electrical connection.

Hereinafter, the manufacturing process of the above-described high-frequency power amplifier of the present invention will be described.

First, paste solder is applied to the back surface of a circuit board on which passive components (chip components such as inductance L, capacitance C, and resistance R) are mounted, placed on a metal base, and fixed by reflow soldering. . Note that an edge clip type lead pin is connected to the circuit board in advance.

Next, on a heat spreader slightly smaller than the transistor mounting hole provided on the circuit board, a mini-molded transistor of several mm square is mounted by solder reflow. Here, it is important that the heat spreader be a good conductor of heat and electricity and a material capable of reflow soldering.
Or plated with Au.

The thickness of the heat spreader is set substantially equal to the thickness of the circuit board. As a result, the upper surface of the heat spreader and the upper surface of the circuit board are aligned, and the heat spreader assembly (with the mini-mold transistor mounted on the heat spreader) is connected to the lead pins extending from the bottom of the mini-mold package on the metal base. Excessive stress during mounting is avoided.

Subsequently, after paste solder is applied to the back surface of the heat spreader assembly, it is set in a predetermined hole of a circuit board on a metal base, and is reflowed and fixed. Simultaneously with this fixing, the lead pins of the mini-mold assembly are also soldered to the wiring pattern on the circuit board.

Finally, after the metal cover and the metal base are engaged, they are bonded and fixed by the method already described. In addition,
The reflow at this time is performed at a relatively low temperature of about 200 ° C. so as not to affect devices mounted inside or soldering already performed.

In this example, a transistor in a mini-mold package is used as a transistor. However, in a frequency band exceeding 1 GHz, good characteristics cannot be maintained due to the influence of an electric parasitic element of the mini-mold package. Cases can arise. In such a case, a bare chip-shaped semiconductor element may be used and may be directly mounted on the heat spreader.

In this case, the thickness of the heat spreader is made thinner than the thickness of the circuit board by the thickness of the bare chip so that the upper surface of the bare chip and the upper face of the circuit board match. By doing so, it is possible to minimize the wire length of the wiring that electrically connects the wiring pattern of the circuit board and the electrode pads in the bare chip.

Further, the bare chip is die-bonded on a heat spreader, and the assembly is soldered in a predetermined hole of a circuit board by reflow soldering, and wiring is performed.
Further, the bare chip and its periphery are protected by a potting resin. Thereby, the bare chip can be effectively protected from the outside air.

[0044]

As described above, according to the present invention, in the packaging of a high-frequency power amplifier, the claws of the metal base are engaged with the holes of the metal cover, and the side surfaces of the metal cover are formed. Since a concave portion having a through hole is provided at a predetermined position of the portion, and the metal lid and the metal base are bonded and fixed by reflow soldering through the through hole, a high-stability high-frequency power amplifier is provided. Can be provided.

Also, since the overhang is provided on the metal cover and the overhang is fixed to the predetermined portion of the circuit board by reflow soldering, a high-frequency power amplifier having higher stability is provided. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a state of packaging of a high-frequency power amplifier according to the present invention.

FIGS. 2A and 2B are diagrams for explaining in detail a structure of a metal base constituting the high-frequency power amplifier of the present invention, wherein FIG. 2A is a top view, FIG. 2B is a side view, and FIG. The state of fitting of a base and a metal lid is shown.

3A and 3B are diagrams for explaining in detail the structure of a metal lid constituting the high-frequency power amplifier of the present invention, wherein FIG. 3A is a top view, FIG. 3B is one side view, and FIG. Is a side view of the other.

4A and 4B are diagrams for explaining the structure of the metal lid when the metal lid is directly fixed to the substrate by soldering, wherein FIG. 4A is a top view and FIG. 4B is AA ′ of FIG. FIG.

FIG. 5 is a cross-sectional view showing an example of a connection structure between a metal base and a metal lid of a conventional high-frequency power amplifier.

FIG. 6 is a cross-sectional view showing another example of a connection structure between a metal base and a metal lid of a conventional high-frequency power amplifier.

[Explanation of symbols]

11, 25, 31, 41 Metal lid 12 Substrate 13,21,43 Metal base 14 Opening 14a, 14b side part 15 claws 16, 32 Side wall material 17, 26, 33 holes 18, 34 recess 19, 35 Through hole 20 Lead pin 22a, 22b side part 23a, 23b, 23c claws 24a, 24b, 24c, 24d Notch 42a, 42b overhang

Continuation of front page    F term (reference) 4E360 AA02 AB12 BA03 BA08 BC05                       CA01 EA18 ED03 ED06 ED07                       ED08 ED13 ED27 FA08 GA06                       GA34 GA53 GB97 GC02                 5J067 AA04 AA41 CA27 CA54 FA16                       QA05

Claims (5)

[Claims] 1. A grounded metal base, a circuit board on which a high-frequency circuit element is mounted and grounded and mounted on the metal base, and a metal fixed to the metal base so as to cover the circuit board. A high frequency power amplifier comprising: a lid; and a side surface having an engagement means at a part of an edge of the metal base, and a hole at a part of the side surface of the metal lid. A high-frequency power amplifier, wherein the engaging means engages with the hole, and the metal lid and the metal base are bonded and fixed by reflow soldering. 2. A concave portion having a through hole is provided at a predetermined position on a side surface portion of the metal lid, and the inside of the side surface of the metal lid provided with the concave portion and the metal base are provided. 2. The high-frequency power amplifier according to claim 1, wherein the side surfaces are bonded and fixed by reflow soldering. 3. The method according to claim 1, wherein the engaging means is a claw processed and the engaging portion between the claw and the hole is fixed by reflow soldering.
3. The high-frequency power amplifier according to 1. 4. The metal cover according to claim 1, further comprising an overhang portion, wherein the overhang portion and a predetermined portion of the circuit board are adhered and fixed by reflow soldering. A high-frequency power amplifier according to any one of the above. 5. The metal lid is made of Au plating or N
The high-frequency power amplifier according to any one of claims 1 to 4, wherein the high-frequency power amplifier is i-plated.