JPS61117862A - High frequency circuit board - Google Patents

Abstract

PURPOSE:To improve the band characteristic, isolation characteristic, and gain flat characteristic by a method wherein an organic polymer is used as the dielectric, and resistance is alternatingly added by surrounding high frequency signal lines with a ground conductor, and by making the power source feed line as the distributed constant line of low characteristic impedance. CONSTITUTION:The organic polymer capable of lamination is used as the dielectric, and the high frequency signal line 16 is surrounded with ground conductors 14 and 17; thereby, the line width of said line 16 is made very small, and the coupling among high frequency signal lines can be inhibited. Besides, the characteristic impedance of a power source feed line 13 coming to distributed constant is reduced, thus constructing this line by termination with a resistor 18, and a high frequency signal line 16 is completely isolated from the power source feed lines 13 with the ground conductors 14 and 17. Thereby, the impedance of the power source feed line 13 in view from the power source terminal of a TC chap 19 is changed to pure resistance, resulting in the suppression of the effect of electrical feedback around the power source.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an electric circuit board used when constructing a high frequency electric circuit device using a high frequency transistor chip or an engineered C chip.

(Prior Art) FIG. 4 shows an example of a conventional high frequency circuit board. (Al is a plan view seen from above, (to) is a cross-sectional view, l is a dielectric,
2 is a metal substrate, 3 is a high I! 1-wave signal line, 4 is a power feed line, 5 is a ground conductor, 6 is an engineered C chip, 7 is a chip capacitor, and 8 is a bonding wire. In this board example, a protrusion is provided in the center of the metal substrate 2 in order to keep the ground potential particularly good in a high frequency circuit board and to suppress heat generation of the IC chip 6. It has a structure in which a dielectric material 1 made of ceramic or the like with holes is bonded together, and a C chip and a transistor chip are directly mounted on the protruding metal substrate portion. Conventionally, it has been common practice to mount active components such as a C chip on such a circuit board to realize a wideband amplifier circuit or the like. In this case, the high frequency signal line 3 should be, for example, 50Ω or 75Ω in order to match the characteristic impedance of the device.
The dielectric 1 is appropriately translated and designed in such a way that a characteristic impedance of .

Conventionally, an alumina substrate with a substrate thickness of about 0.64 fl is often used as the m-electric body of this pole, and the high frequency signal line 3 having a characteristic impedance of 50Ω or 75Ω is usually constituted by a microstrip line, and this alumina substrate When using, the line width of the 50Q high frequency signal llA3 is about 0.6 Jfl. Furthermore, when mounting a C-chip of several angles, the in-wave signal wires 3 will face each other with the IC chip 6 in between at intervals of several angles. Therefore, capacitive coupling occurs between the high frequency signals Is3 and the signal fl3 because the interval between them is as small as several orders of magnitude, and the line width is relatively large, about OB-, resulting in deterioration of isolation between input and output. There is a problem. Figure fJ5 shows the isolation between input and output when high-frequency signal lines with a spacing of 3.5 a%N and 0.64 g are formed on an alumina substrate with a substrate thickness of 0.64 al in the high FI 4-wave circuit board shown in Figure 4. These are the results of actual measurement of characteristics. As is clear from FIG. 5, the isolation characteristic is approximately -50 (IB) at 2Ga15, and from the viewpoint of stability, it is impossible to mount an engineered C chip with a gain of over 50aBJl at 2G-.

In order to improve this isolation characteristic, the high frequency signal line can be made thinner, and in order to make it thinner, the thickness of the dielectric substrate can be made very thin, or the dielectric constant can be increased. However, if the dielectric constant is increased, the coupling with adjacent wiring patterns becomes large, so it is most effective to reduce the dielectric thickness. It has the disadvantage that the degree of isolation is limited and it is not possible to improve the isolation level.

On the other hand, if the power supply feed 8I4 has impedance, the AC grounding will not be complete.
Positive feedback and negative feedback occur, resulting in deterioration of the input/output isolation layer, deterioration of band characteristics, deterioration of flatness of gain characteristics, etc., so the pattern should be designed with consideration to lower impedance as much as possible. ing. However, with the advancement of integrated circuit technology, the mounted C chips have become more high-performance and multifunctional, the number of signal lines and power supply lines has increased, and the patterns of mounted circuit boards have become increasingly complex and dense.
I had to make the line width thinner, which cost me $1! The impedance of the power supply line has become larger and the frequency characteristics have become increasingly broadband, making the impedance of the power supply line no longer negligible.

fJ6 diagram (al) (bl is the shimierance characteristic to show the influence of the inductance of the power supply pattern. The assumed IC chip is the parallel feedback amplifier circuit shown in gJ6 diagram (C). 4 is the 881 (gain) characteristic , (1)) is St
g (isolation wear) characteristic. It can be seen that even when several ml of inductances L and L8 are used as shown in D) (e), the gain and isolation characteristics are significantly degraded.

FIG. 7 shows the Sat characteristics and S1g of a circuit board 11 in which a chip capacitor 7 is connected in the vicinity of an IC chip 6 so as to reduce the impedance of the power supply, as a commonly used method to suppress the above-mentioned deterioration. This is an example of a characteristic. The connection method is as shown in (Q))C, and y) is its equivalent circuit. Note that the line indicated by / is the distribution constant Mg ([1,5&l.

The thickness is 0.64 fl). In this case, resonance occurs due to the inductance of the bonding wire and power feed line and the capacitance of the chip capacitor, causing resonance characteristics in the S12 characteristics and Sit characteristics, and causing problems such as deterioration of the local Iζ gain characteristics and isolation characteristics. However, there were major problems from the viewpoint of realizing a wideband amplifier circuit.

(Objective of the Invention) The present invention uses an organic polymer material that can be made very thin in film thickness as a dielectric material to reduce high and R wave signal line widths.
In addition, the high-frequency signal line is surrounded by a ground conductor to prevent coupling between the high-frequency signal lines, and the power feed line is connected to a wire with a small characteristic impedance and terminated at that characteristic impedance for alternating current, and the area of the power feed line is To provide a high frequency circuit board that makes it as large as possible and thins the dielectric thickness to increase capacitance and lower impedance, thereby making it possible to flatten the gain characteristics, widen the band, and improve the isolation shadow characteristics. The purpose is to

(Structure and operation of the invention) The present invention will be explained in detail below.

FIG. 1 shows an embodiment of the high frequency circuit board of the present invention.
1 is a metal substrate, 12 and 15 are dielectrics, 13 is a distributed power supply feed line, 14 and 17 are ground conductors, 1
6 is a high frequency signal line, 18 is an I11 film resistor, and 19 is an engineered C chip. In contrast to the conventional example 3ζ shown in FIG. 4, the present invention has a structure in which the high frequency signal line is thinned and completely surrounded by a ground conductor to prevent coupling between adjacent signals #1. Furthermore, the power feed line and the high frequency signal line can be easily formed on the same substrate. 1t
aL2 is the characteristic impedance of the power supply feed line 13, which is 1
It is formed with a very thin thickness in order to reduce the thickness to about Ω or less. This dielectric 12 is formed by spray coating an organic polymer layer such as polyimide on a metal substrate 11, and has a very thin thickness of approximately S#.

Ei1′ again? The IL body 15 is made of an organic polymer having a dielectric constant of 5 or less in order to shorten the propagation delay time of the signal in the high frequency signal line 16, and is suitable for designing the characteristic impedance of the high frequency signal line 16 to 50Ω or 75Q. It requires a certain thickness. In fact, when the width of the high-frequency signal line 16 is set to 50 μm, the characteristic impedance of Cζ can be set to 50 Ω by making the thickness of the dielectric 15 approximately 100 μm.

AC is terminated with its characteristic impedance, and is formed using conventionally well-known thin film technology.

Next, a method for manufacturing a high frequency circuit board according to the present invention will be described in detail.

First, as shown in FIG. 1, a low dielectric constant organic polymer varnish is applied onto a metal substrate 11 using a spin code method or a spray coating method, patterned using photolithography technology, and then cured at a high temperature to form a low dielectric constant insulating pattern. Form. Next, a conductor thin film is formed by ion blating method and sputtering method, and distributed constant #l & ! is formed by photolithography technology. -Power supply feed with the same line width so that it is -! 1
113 is formed. Here, in order to surround the power feed line 13 with a dielectric material, a low dielectric constant insulating pattern is again formed on it in the same manner as described above.
! Insert the lead wire 13 inside the weight 2 inside the lta body 12.

Thereafter, the layers are sequentially laminated by the method shown below.

The ground conductor 14 is formed into a film by a vapor deposition ion-blating method or a sputtering method, and the pattern is formed by mask vapor deposition to form an fζ pattern at the same time as WX formation. The dielectric weight 5 is formed by the same method as the dielectric 12. The high frequency signal M16 is formed by photolithography after mask deposition. Finally, the top layer, the ground conductor 1
7 is formed by the same method as the grounding conductor 14, subjected to surface treatment, and completed.

What is noteworthy about this manufacturing method is that the low dielectric constant organic polymer varnish can be produced using the spin code method or c.

The spray coating method has the characteristic that it can easily form thick films from several microns to several tens of microns by changing the viscosity of Fes and the spin speed in the case of spin code, and it is also possible to form thick films from several microns to several tens of microns. It is possible to form both on the same substrate.

As described above, the present invention uses an organic polymer that can be made thinner as a dielectric material, and also transmits a high frequency signal m1.
6 is surrounded by ground conductors 14 and 17, the line width of the high frequency signal line 16 can be made extremely narrow, and coupling between the high frequency signal lines can be suppressed. Also, a distributed constant power supply feed! By lowering the characteristic impedance of 113 and terminating it with a resistor 18, the high-frequency signal line 16 and power feed line 13 are completely separated by ground conductors 14 and 17. feed 1
The impedance of i13 can be made into a pure resistance, and the resistance value can be made small, suppressing the electrical feedback effect around the power supply and allowing high R1 from the power supply feed line 13.
1 signal I! It is also possible to prevent the adverse effects of the signal line characteristics on the 16. This effectively prevents deterioration of band characteristics as a high frequency circuit board, deterioration of flatness characteristics of gain characteristics, and deterioration of isolation characteristics. The desired shemirelation result of the effect of the power feed line is shown in FIG. The circuit shown in FIG. 6 was used as the simulation circuit. In Fig. 2, the broken line ■ indicates that the power supply line is not terminated using a line with a length of 10tlIWI and a characteristic impedance Zθ of 50Ω, the dashed line ■ terminates at 50Q, and the solid line ■ indicates the lowered characteristic impedance 0 as described above. .58Ω f
This is the case when the Ii source feed line is used.

It can be seen that in the case of one point #4M■, the impedance seen from the power supply terminal of the IC chip E 9 is pure resistance.

Furthermore, in the case of the solid line @, only the effect of the inductance of the bonding wire for connecting the circuit chip 19 and the mounted circuit board appears, and it can be seen that the influence of the mounted circuit board is almost eliminated. Compared to the conventional characteristics shown in FIG. 7, it is possible to greatly improve the flatness of the inlay frequency characteristics and band characteristic gain.

Here, if the terminating resistor 18 of the power feed line 13 is not used, the characteristic impedance of the electric power feed 4113 is as small as IQ, and in reality, there is loss in the feed line, so it is not necessary to terminate it (but the initial It thickens (does not impair) the effect of (the effect is the same).

FIG. 3 shows another embodiment of the high frequency circuit board of the present invention,
21 is a metal substrate, 22 and 25 are dielectrics, 23 is a power supply feed, 24 and 27 are ground conductors, 26 is a high frequency signal line, and 29 is an engineered C chip. This embodiment differs from the first embodiment in that the line width of the power feed bundle 23 is made as wide as possible. In this way the power feed 5123! If llK is set as wide as possible, the power feed line 23 will have a large capacitance of 100FF or more, and the power feed ts23 will become a line with extremely low impedance, making it possible to achieve the same effects as in the first embodiment. becomes.

Note that this high frequency circuit board is manufactured by the same method as in Example 1.

(Effects of the Invention) As explained above, the present invention uses an organic polymer as a dielectric, and surrounds a high frequency signal line with a ground conductor.
c1! ! By making the 11 feed line a distributed constant line with low characteristic impedance and terminating it by adding a resistance in an AC manner, the impedance seen from the power supply terminal of the C chip or transistor chip is made into a pure resistor with a low resistance value. This has the advantage that coupling between signal lines and feedback effects due to the circuit board around the Il source can be suppressed, and band characteristics, in-resistance characteristics, and gain flatness characteristics can be improved.

Also, the dielectric thickness between the power feed line and the ground conductor is 10
The same advantages as described above can be obtained by making the capacitance as large as a μ-sized piece and increasing the capacitance (thus lowering the impedance).

Furthermore, by using organic polymers as dielectrics, it is possible to arbitrarily produce two or more types of dielectrics with different thicknesses on the same substrate, and as a result, a low impedance power supply line and a 50Ω Alternatively, it has the advantage that a high frequency signal line having a characteristic impedance of 75Ω can be formed on the same substrate.

Further, the dielectric material can have a dielectric constant of 5 or less, and the signal propagating through the KR wave signal line can be transmitted at high speed.

Furthermore, since a metal plate several tens of meters thick is used as the substrate and the C-chip is directly mounted on it, heat dissipation is improved and heat generation of the C-chip is prevented. Further, for the same reason, the ground potential is stabilized even during high frequency operation, and there is an effect of preventing deterioration of unstable operation characteristics due to fluctuations in the ground potential. Furthermore, for the same reason, if a metal plate several nanometers thick is used with the top surface of the chip as the right cover, the IC chip will have a structure sandwiched between the upper and lower thick metal plates, making it difficult for the IC chip to be exposed to radiation in the space environment. It has the effect of protecting.

[Brief explanation of drawings]

Fig. 1 (al is a partially cutaway perspective view of the high frequency circuit board of the present invention, Fig. 1 (b) c) Fig. 1 (ag) a-a' sectional view, Fig. 2 (al and ('b) 1 is a circuit characteristic diagram for explaining the theoretical effect of the high frequency circuit board, FIG. 3 is a partially cutaway perspective view showing another embodiment of the present invention, Figure 3) is a cross-sectional view taken along line a-a', Figure 4 (at is a plan view of a conventional high-frequency circuit board, Figure 14 ('b) is a cross-sectional view of the fourth
Fig. 5 is a diagram of the circuit characteristics of the 45-inch high-frequency circuit board, Fig. 6 is a cross-sectional diagram of Fig. (a),
(d), Tel is a characteristic diagram showing the effect of the impedance of the idle power source wire on the circuit characteristics of the conventional high frequency circuit board H, and its usage circuit diagram and equivalent circuit diagram, Figure 7 (al, ('b), (C1, ((1) is a conventional high frequency circuit board 1 circuit 2.11.21 - metal board 4.13.23 - power feed line 3.16.26 - signal line 6.19.29
-IC chip 18---, -resistance patent applicant (442) Nippon Telegraph and Telephone Public Corporation (663) Kyocera Corporation Misa)> Cao 6 zw stomach) t)〉knee) m to sekai ＼ Q for shifu number (6H Otonagata Town

Claims (6)

[Claims] (1) A high frequency circuit board characterized in that the impedance of the power feed line with respect to a ground conductor is low, the high frequency signal line is surrounded by a ground conductor, and the power feed line and the signal line are formed on the same metal plate. (2) The high frequency circuit board according to claim 1, wherein the power feed line and the high frequency signal line are embedded in a dielectric material made of an organic polymer having a dielectric constant of 5 or less. (3) The high frequency circuit board according to claim 1, wherein the power feed line is a distributed constant line with low characteristic impedance. (4) The impedance of the power feed line with respect to the ground conductor is low, the high frequency signal line is surrounded by a ground conductor, the power feed line and the signal line are formed on the same metal plate, and power is supplied by the power feed line. 1. A high frequency circuit board, characterized in that a resistor is arranged on the power supply line to terminate the power supply line in an alternating current manner so that the impedance when viewed from the power supply terminal of an active device chip appears to be a pure resistance. (5) The high frequency circuit board according to claim 4, wherein the power feed line and the high frequency signal line are embedded in a dielectric material made of an organic polymer having a dielectric constant of 5 or less. (6) The high frequency circuit board according to claim 4, wherein the power feed line is a distributed constant line with low characteristic impedance.