JPS5936916Y2 - High frequency hybrid integrated circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hybrid integrated circuit board for high frequency circuits that uses a transistor chip without a case.

Conventionally, transistor chips used in hybrid integrated circuits have been protected from the outside air by using a ceramic or metal case when high reliability is required, and a resin case for consumer products.

As shown in FIGS. 1 and 2, due to this case C, the size of the transistor chip becomes large, and as the operating frequency increases, the characteristics deteriorate due to the influence of parasitic elements.

Also, if the power consumption of the transistor chip is large,
In order to dissipate heat, it is necessary to take measures for heat dissipation, such as providing a heat dissipation stud e and a heat sink f in the case, which further increases the size of the case b.

In consideration of this higher frequency and heat dissipation, recent hybrid integrated circuits use alumina or beryllia as substrates, which have good thermal conductivity.
Attempts have been made to directly mount transistor chips on these substrates, but in order to protect the transistor chips, they are coated with resin or the entire substrate is sealed in a case.

The former had problems in terms of reliability, and the latter had difficulties in making adjustments to the circuit.

Further, in a multilayer board for high frequency, the wiring on the board surface has a stripline structure.

The lower limit of this line width is determined by manufacturing conditions such as photo-etching and the condition of reducing series resistance.

Therefore, in consideration of higher frequencies, a lower limit is set for the thickness of the multilayer substrate, and even if transistors are directly mounted on the multilayer substrate, there is a problem in terms of heat dissipation.

In order to solve these drawbacks, the present invention has been developed by housing a transistor chip in a recess in a multilayer edge line board made of alumina or Berria, sealing it by covering it with a sealing girder, and reducing the thickness of the board after sealing. Its purpose is to protect the transistor chip, reduce the number of parasitic elements in the circulation, increase the frequency, facilitate heat dissipation, and adjust the circuit characteristics as usual. It is an object of the present invention to provide a hybrid integrated circuit board that can be used.

Figure 3 is a cross-sectional view of the hybrid integrated circuit board according to the present invention;
The figure is a plan view.

1 is an alumina or berria multilayer substrate, 2 is a transistor chip, 3 is a conductor button for a transistor collector,
4 is a metallized part for sealing, 5 is a metallized part of the sealing lid 9, 6 and 6' are through holes for establishing electrical conduction with the surface of the board, 7 are through holes for electrical conduction between the front and back sides of the board, and 8 is a through hole for the circuit. Each conductor button is shown.

FIG. 5 shows the temperature distribution of the Berria substrate.

The size of the board is 50 x 50 mm, thickness 1.0 mm
This is an actual value when a 1.5 Watt heating element is placed at the center of the board.

The horizontal axis shows the distance from the center of the heating element, and the vertical axis shows the temperature.

It can be seen that the temperature gradient from the stop to the edge of the substrate is small, indicating extremely good heat transfer.

This will be explained below with reference to the figures.

As shown in FIG. 3, the transistor chip 2 has a recess 1 in the center, which is formed by removing two layers of the substrate from the surface of the substrate 1.
Since the transistor is bonded directly to the bottom of the transistor, heat dissipation of the transistor is efficiently carried out through the bottom substrate, and as shown in FIG. 5, the transistor junction temperature can be kept extremely low.

Further, the transistor chip 2 is sealed in the recess 10 by bonding the substrate metallization 4 and the metallization 5 of the sealing lid 9 with metal solder.

By using the horizontal strap as shown in Fig. 3, the thickness of the hybrid integrated circuit board after attaching the sealing lid 9 becomes uniform, making it convenient for etching, etc., when manufacturing a hybrid integrated circuit on a board using a tantalum thin film, for example. The process becomes easier.

The electrodes of the transistor chip 2 are drawn out from the four electrode lands (conductor patterns 3) through through holes 6, and can be connected to other lands by conductor patterns 8 as shown in FIG. 4, if necessary.

Therefore, since it is possible to seal only the transistor portion in this way while using a transistor chip, the circuit can be adjusted in exactly the same way as in the conventional circuit without deteriorating the reliability of the transistor.

Also, since a transistor chip is used, the signal loop is shortened, making it suitable for higher frequencies.

As can be seen from the above description, the present invention is effective as a substrate for a high frequency circuit that requires a transistor chip with large power consumption and requires high reliability of the transistor.

Especially for FDM where you want to keep the signal feedback loop as short as possible (
This effect is remarkable for hybrid integrated circuits for frequency division multiplexing (frequency division multiplexing) and high frequency PCM (pulse code modulation) systems.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional hybrid integrated circuit board, Fig. 2 is a plan view thereof, Fig. 3 is a sectional view of a board according to the present invention, and Fig. 4 is a sectional view of a conventional board for hybrid integrated circuits.
The figure is a plan view thereof, and FIG. 5 is a temperature distribution diagram of this substrate. Explanation of symbols, 1... Ceramic substrate, 2...
...Transistor chip, 3...Conductor pattern, 9...Sealing lid, 10...Recessed portion.

Claims (1)

[Scope of utility model registration request] A high-frequency hybrid integrated circuit board having a multilayer structure having a conductor pattern between layers, the board having a recess for storing a transistor formed by removing one or more layers from the surface of the board, and the recess being made of the same material as the board. 1. A high-frequency hybrid integrated circuit board, characterized in that a sealing lid is provided, and the thickness of the lid is selected so that the thickness of the substrate after sealing is uniform.