JPS6144433Y2 - - Google Patents

Description

[Detailed Description of the Invention] As is generally known, semiconductor elements such as transistors are molded in resin or mounted in metal or ceramic packages for the purpose of stabilizing and protecting the atmosphere. In particular, ceramic packages are used in high frequency band transistors, such as potassium arsenide field effect transistors, because of their excellent high frequency properties, mechanical strength, thermal conductivity, and the like.

FIG. 1 shows a schematic structure of the potassium arsenide field effect transistor.

In the figure, a prismatic cylindrical base 1 made of ceramic has its lower surface metallized and is soldered or adhered to an earth electrode E with a conductive adhesive. , a gate electrode G and a drain electrode D are formed integrally with the base body 1 at positions slightly above the bottom surface, with one end face facing each other within the base body 1 and the other end protruding outward. Further, a metallized layer 3 for soldering or welding the lid 2 is formed on the upper surface of the base 1, and a metallized layer 4 for connecting the metallized layer 3 to the metallized layer on the lower surface of the base 1 is formed on the upper surface of the base 1. It is formed on the side surface 1'' and the outer surface of the base body 1 facing the side surface 1''.

The terminals of the semiconductor element 5 fixed to the ground electrode E within the substrate 1 are connected to the corresponding terminals of the gate electrode G by lead wires 6,
It is connected to the terminal with a lead wire 6'.

On the other hand, the lid 2 has a metallized layer formed on its lower surface, and the metallized layer is soldered or welded in contact with the metallized layer 3 on the upper surface of the base 1 to seal the semiconductor element 5.

Transistors in such ceramic packages are suitable for high frequency bands, i.e.
Feedback occurs through the metallized layer 3 in a frequency band where the inductance of the metallized layer 4 formed in the above cannot be ignored due to the characteristics of the transistor.

FIG. 2 is an equivalent circuit of the potassium arsenide field effect transistor shown in FIG. , corresponding to the gate electrode G, L ₁ is the inductance of the metallized layer 4, L ₂ is the inductance of the metallized layer (not shown) facing the metallized layer 4,
L ₃ is the inductance of the lead wire 6, L ₄ is the inductance of the lead wire 6', C ₁ is the capacitance between the gate electrode G and the metallized layer 3, C ₂ is the capacitance between the drain electrode D and the metallized layer 3,
C ₃ represents the capacitance between the earth electrode E and the gate electrode G, and C ₄ represents the capacitance between the earth electrode E and the drain electrode D.

In Fig. 2, when the cutoff frequency band is high, for example about several tens of GHz, inductances L ₁ and L ₂ cannot be ignored, and part of the output of drain electrode D is caused by capacitance C ₂ , metallized layer 3, capacitance C ₁ returns to the gate electrode G and is added to the input signal, so-called feedback occurs, and the transistor oscillates or operates unstablely. This oscillation and unstable operation become particularly noticeable at the resonance frequencies of the drain electrode D and the metallized electrode 3, and the generation of harmonics increases.

The purpose of the present invention is to suppress the above-mentioned feedback and eliminate oscillation and unstable operation.The purpose of the present invention is to suppress the above-mentioned feedback and eliminate oscillation and unstable operation. This is accomplished by providing a package.

The present invention will be explained below using the drawings.

FIG. 3 shows a transistor package according to one embodiment of the present invention, and FIG. 4 shows a transistor package according to another embodiment of the present invention. The metallized layer 3, metallized layer 4, earth electrode E, drain electrode D, and gate electrode G are the same as those shown in FIG.

In FIG. 3, the radio wave absorber film 7 covering the top surface of the lid 2 is made by pasting a rubber sheet containing ferrite with a suitable adhesive, or coating it with a paint containing carbon or the like.

In FIG. 4, a radio wave absorbing lid 2' made of an object containing a radio wave absorber and having airtightness, such as a ferrite plate, is soldered to the upper surface of the base 1. In FIG.

In the transistor package according to the present invention having the structure explained above, the radio wave absorber absorbs the electromagnetic waves generated from the transistor, converts it into thermal energy, and releases it, thereby reducing feedback within the package or eliminating resonance. By bringing about the effect of lowering the Q value of the transistor and removing the factors that cause oscillation and unstable operation, the transistor characteristics and reliability can be improved, and its practical effects are great.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a ceramic package of a potassium arsenide field effect transistor, Figure 2 is an equivalent circuit of the potassium arsenide field effect transistor shown in Figure 1, and Figures 3 and 4 are transistor packages according to embodiments of the present invention. Explanatory diagram. DESCRIPTION OF SYMBOLS 1... Base body, 2... Lid, 2'... Lid of radio wave absorber, 3, 4... Metallized layer, 7... Radio wave absorber film.

Claims (1)

[Scope of utility model registration request] 1. A ceramic package for a transistor comprising a base body whose upper end surface is metallized and a lid closely attached to the metallized layer, wherein at least the upper surface of the lid is made of a radio wave absorber.