JPH08288614A - Structure for high-frequency transistor circuit - Google Patents

Abstract

PURPOSE: To obtain a stable connecting structure which does not require soldering for connecting the gold-plated lead of a high-frequency transistor and can withstand thermal stresses. CONSTITUTION: The collector 2 of a high-frequency transistor 1 is put between a gold-plated wiring pattern and dielectric substrate 10 on a printed board 7 and fixed with a screw 12 through a metallic plate 11. In addition, wiring patterns connected to each other through a through hole are formed on both surfaces of a dielectric substrate 13 and one of the patterns is plated with gold, with the other being plated with solder, etc. Then the base 3 of the transistor l is put between the gold-plated wiring pattern on the printed board 7 and the gold-plated pattern on the dielectric substrate 10 and fixed with screws 15 through the metallic plate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency transistor circuit structure, and more particularly to a structure for electrically connecting the leads of a high frequency transistor to a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, the lead connection structure of this type of high-frequency transistor has been performed by soldering the leads to a printed circuit board. The connection structure will be described below by taking an NPN transistor for high frequency as an example. FIG. 7 is a plan view showing a conventional lead connection structure, and FIG. 8 is A- of FIG.
A sectional view in B is shown.

In the figure, the lead portion of the transistor 1 comprises a collector 2 and a base 3, each of which is plated with gold. After removing the gold plating in a hand bath or the like, the plate 4 forming the emitter of the transistor 1 is fixed to a conductor 5 such as a radiator with screws 6. After that, the collector 2 and the base 3 are connected to the printed pattern 8 formed on the printed circuit board 7 by using the solders 24 and 25. Further, the input circuit component 16 of the base 3 is mounted near the transistor 1 by soldering.

[0004]

This conventional high frequency transistor circuit structure uses solder to connect the leads of the gold plated high frequency transistor and the printed pattern on the printed circuit board. Since the alloy of gold and solder is not suitable for high frequency connection, it is necessary to remove the gold plating using a solder bath or the like in order to prevent the alloy formation of gold and the hand, which complicates the connection process. Also, because the heat generated from the transistor is applied to the leads,
There is a problem that the solder used for connection deteriorates.

Further, when the high frequency transistor circuit is used in a mobile communication system, the high frequency transistor which is amplifying the high frequency is frequently turned on / off.
Will be repeated. At this time, heat is applied to the transistor lead and the printed circuit board having different thermal expansion coefficients,
A heat cycle that is not done occurs, different expansion and contraction occur, which becomes thermal stress,
Mechanical stress is added to the solder. Then, microcracks are generated in the solder, the resistance of the transistor leads and the contact resistance with the printed circuit board increase, and heat is generated, and finally the solder melts and the connection becomes defective.

Therefore, the object of the present invention is to provide a high-frequency transistor circuit structure which eliminates the drawbacks of the prior art and provides a reliable and stable connection between the high-frequency transistor and a printed circuit board.

[0007]

In the high frequency transistor circuit structure of the present invention, the leads of the gold plated high frequency transistor are sandwiched between the partially gold plated wiring pattern on the printed board and the dielectric substrate, The body substrate and the printed circuit board are fixed to each other with screws via a metal plate.

Wiring patterns are formed on both surfaces of the dielectric substrate, connected by using through holes, the through holes are filled with metal, and the wiring pattern on one surface is plated with gold, and the other surface is electrically connected. The parts are plated for soldering.

[0009]

The present invention will be described below with reference to the drawings. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AB of FIG. 1, and FIG. 3 is an equivalent circuit of FIG.

This embodiment is a push-pull high-frequency high-power transistor (NPN) used in a high-frequency amplifier.
Is a lead connection structure of a high-frequency transistor using a shape. In the figure, the lead portion of the transistor 1 is composed of a collector 2 and a base 3, each of which is plated with gold. The plate 4 forming the emitter of the transistor 1 is fixed to a conductor 5 such as a radiator with screws 6. Next, the lead of the collector 2 of the transistor 1 is sandwiched between the dielectric substrate 10 and the partial gold plating 9 of the wiring pattern 8 formed on the printed circuit board 7 fixed to the conductor 5 such as a radiator.
The dielectric substrate is fixed to the conductor 5 with screws 12 through a metal plate 11 such as aluminum so as not to be broken. Here, an alumina substrate having a good thermal conductivity is used as the dielectric substrate 10.
Furthermore, the lead of the base 3 of the transistor 1 is similarly fixed to the conductor 5, and the partial gold plating 9 of the wiring pattern 8 formed on the printed board 7 and the dielectric substrate 13 having the wiring pattern on the gold plating wiring pattern side. And the dielectric substrate 13 is fixed to the conductor 5 with a screw 15 via a metal plate 14 such as aluminum so as not to break.
On the dielectric substrate 13, a component 16 such as a capacitor necessary for the circuit is soldered.

Plan views of the dielectric substrate 13 are shown in FIGS.
5 is a sectional view taken along line AB of FIG. FIG. 6 is a three-dimensional view. In the figure, the wiring pattern 18 formed on the front surface of the dielectric 17 and the wiring pattern 1 formed on the back surface
9 is connected by through hole 20 and metal 2
This through hole 20 is filled with 1. After that, the wiring pattern 19 is treated with gold plating 22,
The wiring pattern 18 is plated 23 so that the circuit component 16 can be easily attached. In this embodiment, the dielectric 17 is alumina, the metal 21 is tungsten, and the wiring pattern 23 is plated with nickel and solder.

[0012]

As described above, according to the present invention, the collector lead of the high frequency transistor is sandwiched between the wiring pattern on the printed circuit board and the dielectric substrate, and the dielectric substrate and the printed wiring board are fixed with screws via the metal plate. Also, form the wiring pattern on both sides of the base lead and the wiring pattern on the printed circuit board and the dielectric, connect using the through hole, fill this through hole with metal, and perform gold plating on the wiring pattern on one side. , On the opposite surface, sandwich it so that it contacts the gold-plated wiring pattern example of the dielectric board on which the parts are plated by soldering.
By fixing the dielectric substrate and the printed wiring board with screws through the metal plate, the high frequency transistor can be connected without soldering.

Further, by using alumina having a high thermal conductivity as the dielectric, the heat applied to the leads of the transistor can be easily dissipated.

Further, even if the lead of the transistor is repeatedly expanded and contracted, since it is fixed by the dielectric material, there is no microcrack like solder, and the gold plated portion is stable as the contact surface. It is also possible to prevent deterioration over a long period of time.

Also, by filling the through hole with a metal so that one side of the dielectric substrate can be plated with gold and the other can be plated for soldering of components, the other side can be secured while ensuring contact with the transistor lead. In terms of, there is an advantage that parts can be easily attached and adjusted.

Further, according to the structure of the present invention, even if the transistor should fail, it can be easily replaced by removing the screw. If ceramic such as alumina is used for the dielectric substrate, high frequency loss is small and stable use can be achieved for a long period of time.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

2 is a cross-sectional view taken along the line AB in FIG.

FIG. 3 is an equivalent circuit of FIG.

FIG. 4 is a plan view of the dielectric substrate shown in FIG.

5 is a cross-sectional view of the surface of FIG. 4 taken along the line AB.

6 is a three-dimensional view of the dielectric substrate of FIG.

FIG. 7 is a plan view of a conventional high frequency transistor circuit structure.

8 is a cross-sectional view taken along the line AB of FIG.

[Explanation of symbols]

 1 Transistor 2 Collector 3 Base 4 Print (Emitter) 5 Conductor 6 Screw 7 Printed Circuit Board 8 Wiring Pattern 9 Partial Gold Plating 10 Dielectric Substrate 11 Metal Plate 12 Screw 13 Dielectric Substrate 14 Metal Plate 15 Screw 16 Component 17 Dielectric 18 Wiring Pattern 19 Wiring pattern 20 Through hole 21 Metal 22 Gold plating 23 Plating 24 Solder 25 Solder

Claims (5)

[Claims] 1. When a lead of a high frequency transistor which is plated with gold and a wiring pattern on a printed circuit board are electrically connected, the lead of the transistor is partially plated with gold on the printed circuit board and a dielectric substrate. A high-frequency transistor circuit structure, characterized in that the dielectric substrate and the printed wiring board are sandwiched between and fixed to each other with screws through a metal plate. 2. The high frequency transistor circuit structure according to claim 1, wherein wiring patterns are formed on both surfaces of the dielectric substrate, and the both surfaces are connected using through holes. 3. The high frequency transistor circuit structure according to claim 2, wherein a wiring pattern on one surface of the dielectric substrate is plated with gold. 4. The high frequency transistor circuit structure according to claim 3, wherein a wiring pattern on the other surface of the dielectric substrate is plated so that an electric component can be attached. 5. The high frequency transistor circuit structure according to claim 2, wherein the through hole is filled with metal.