JPS63127559A - Hybrid integrated circuit - Google Patents

Abstract

PURPOSE:To detect large currents while directly detecting large currents flowing through a power semiconductor element, and to prevent the breakdown of the power semiconductor element by using one part of a conduction path formed to a metallic substrate as a current detecting resistor. CONSTITUTION:A conduction path 2 is shaped onto an insulating thin-layer formed onto a metallic substrate 1, and a low resistor section is shaped by utilizing one part of the conduction path 2 near a power semiconductor element 3 fixed onto the conduction path 2 and employed as a detecting resistor 4 for detecting large currents. Accordingly, large currents can be caused to flow through the detecting resistor 4 having low resistance, and heat is dissipated sufficiently even when the detecting resistor 4 generates heat by large currents while the deformation of the substrate 1 can he prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a hybrid integrated circuit, and more particularly to an improvement in a hybrid integrated circuit that detects current using a detection resistor with a low resistance value.

(B) Prior Art Conventionally, a bridge circuit has been used as a means for detecting current. As is well known, this current detection bridge circuit detects current by utilizing the balance condition of the bridge.
To briefly explain the circuit (see Figure 10),
The current 1 in the current detection resistor R0 (21). Suppose that is flowing. This current 1. The maximum value of is the resistance R, (21)
Each resistor RI (
22), R1(23), R, (25), R
, (24) are set. Resistor R6 of this bridge circuit (
21), if a current less than the maximum value of the current I0 flows through the comparator (26), a signal at the level r L is no longer output, and a current ■ flows through the resistor R, (21). If a current exceeding the maximum value of is flowing, the voltage input to the humparator (26) is reversed, and a signal of Hj level is output, cutting off current 1 and protecting the circuit.

Such a bridge circuit is described in Japanese Patent Laid-Open No. 53-97470.

When the above-mentioned bridge circuit is used in a thick film IC, the current is 1.
Ni plating was mainly used for the resistor of the resistor R0 that detects the . However, since Ni plating has a small fusing current, it is possible to detect small currents, but when detecting large currents, the area or thickness of the resistor must be increased to minimize the fusing current. However, there are problems such as a reduction in the board mounting area and an increase in plating processing time, and it has been considered almost impossible to detect a large current of, for example, 40A.

In order to solve this problem, it is possible to solve the problem by using copper foil or Ag paste, which has a large resistor fusing current of the current detection resistor R0.

(c) Problems to be Solved by the Invention It is possible to detect large currents by using Ag paste or copper foil, which has a large fusing current.

It is true that the copper foil has a small resistivity of 0.5 mΩ and the Ag paste has a small resistivity of 37 mΩ, so a large current can flow through it. However, since Ag paste is formed by mixing Ag powder into the paste material and forming it by screen printing, etc., there is a problem that the resistance area becomes large.Furthermore, if copper foil is formed on a printed circuit board and a large current is passed through it, the printed circuit board will be heated due to heat. There was a problem in that it deformed.

Further, copper foil has the problem that it cannot be used as a detection resistor because a constant resistance cannot be obtained due to side etching during etching and variations in thickness during the rolling process of the copper foil. Furthermore, the TCR (temperature coefficient of resistance) of copper foil and Ag paste is 3800±200 ppm and 2150±1
Since the resistance is extremely high at 50 ppm, there is a large variation in resistance with respect to temperature changes, which poses a problem in that the current cannot be detected accurately.

(d) Means for solving the problems The present invention has been made in view of the above-mentioned problems.
As shown in FIG. 1, a conductive path (2) is formed on a thin insulating layer formed on a metal substrate (1), and the vicinity of a power semiconductor element (3) fixed on the conductive path (2). conductive path (2
) is used as a detection resistor (4) for current detection to provide a hybrid integrated circuit that detects current.

(*) Function According to the present invention, a part of the conductive path (2) formed on the insulating thin layer on the metal substrate (1) is connected to the detection resistor (4) for current detection.
), a large current can be passed through the low-resistance detection resistor (4), and even if the detection resistor (4) generates heat due to the large current, sufficient heat dissipation can be achieved and deformation of the board (1) can be prevented. be able to.

(F) Embodiment An embodiment of the present invention will be described below in detail with reference to FIGS. 1 to 3.

As shown in FIGS. 1 and 2, the hybrid integrated circuit of the present invention includes a metal substrate (1), an insulating thin layer (5) formed on the metal substrate (1), and an insulating thin layer (5) formed on the insulating thin layer (5). A conductive path formed in (
2), a power semiconductor element (3) fixed on the conductive path (2), and a detection resistor R0 (4) using a part of the conductive path (2) formed near the power semiconductor element (3). It consists of

An aluminum substrate is used as the metal substrate (1), and an aluminum oxide film is formed on its surface by anodizing.

An insulating thin layer (5) of resin such as epoxy resin or polyimide resin is formed on the main surface of the metal substrate (1) on which the aluminum oxide film is formed. Although an aluminum oxide film was formed here, it is also possible to form an insulating thin layer (5) of polyimide resin or the like directly on the metal substrate (1).

The conductive path (2) is formed by pasting a 35 μm thick copper foil on the metal substrate (1) via the insulating thin layer (5), etching it into a predetermined pattern to form a bridge circuit, and then bonding. Ni plating is applied to the parts where this is to be done.

A power semiconductor element (3) and other circuit elements such as chip resistors, chip capacitors, monolithic ICs, etc. are fixedly formed on the conductive path (2), and a resistor R1 ( 6)', R.

(7), R5(s), R4(9), a diode (10), and an integrated IC (comparator) (11) are fixedly formed. Resistors R1Rt, Rs, R4 are formed by screen printing of resistor paste, and diodes (10)
A chip component is used and is bonded to a nearby conductive path (2) by ultrasonic bonding or the like to form a bridge circuit.

To specifically explain the configuration of the bridge circuit, the third
As shown in the figure, the detection resistor R11 (4) and the detection resistor R11 (
4) and a third resistor RS(S) connected in series with the first resistor RS(S).
a resistor R, (6), a second resistor Rt (7), and a diode D (10) connected in series with the second resistor Rt (7).
), the fourth resistor R4 (9), and the first and second resistors R
, (6), and a comparator (11) connected to the connection point of Rt(7) and the connection point of the third and fourth resistors R1(s) and R4(9), and rL from the comparator. .

When a level signal is output, the power semiconductor element (3
) is configured with a control circuit that controls to cut off the large current flowing through the detection resistor R@(4).

FIG. 4 is an equivalent circuit diagram showing the control circuit, and the resistor R6 is a detection resistor R6 (
4). Now, r L from Hunparator (11),
If a level signal is output, the transistor 'r
rt(ta) and Try(17) are turned on, the signal input to the base of transistor Tr, (18) is bypassed to the collector of transistor 'rrt(t7), and transistor T r *(18) is turned off. When the transistor T r s (1B) is turned off, the transistor T r s (19) is turned off, the large current is cut off, and the power semiconductor element (3) is protected.

One feature of the present invention is that a part of the low-resistance conductive path (2) is used as the detection resistor Ro (4). Used for Re(4). A bridge circuit is formed near the detection resistor R (4), and a key-shaped protrusion 12) is provided at the end of the detection resistor R (4) for adjusting the detection resistor R6 (4). is formed. This protrusion (12) is at point a
The resistance of the detection resistor R (4) between -b is adjusted, and the adjustment method will be described below.

The protrusion (12) and the detection resistor Re (4) are connected by a connecting body (13) such as Ni plating. Here, Ni plating is used for the connecting body (13), but any type of connecting body can be used as long as it connects the protrusion (12) and the detection resistor R@(4). The internal resistance of the detection resistor R, (4>) in the part connected by the connection body (12) is very low and can be ignored due to its wide width, and the resistance of the entire detection resistance R@(4) is ), that is, the sum of the internal resistance of the protrusion (12) 4!+ from arbitrary point P to point a and the ultra-low internal resistance from arbitrary point f!1 to point a. be.

Therefore, any point on the protrusion oz)L of the detection resistor R#(4)! By changing the resistance, the resistance of the detection resistor R# (4) can be adjusted. That is, any point 2 at the trimming slit (14) distance of the connecting body (12)! is determined, any point from point a! The internal resistance of the distance up to 8 is the detection resistance Re.
The resistance value is as shown in (4), and fine adjustment can be easily made.

To adjust the other detection resistor (4), as shown in FIG.
The resistance of the detection resistor R6(4) can be adjusted by bonding a predetermined position of the detection resistor R@(4) and changing the arbitrary point 18.

Fig. 5 is a characteristic diagram showing the relationship between conductor width and fusing current when a conductor is formed on a metal substrate (aluminum) and a printed circuit board. Looking at it, the fusing current for the metal substrate is about 47A, while the fusing current for the printed circuit board is about 12A. Printed circuit boards have poor heat dissipation properties.<Thickness and width must be large for the conductors that flow large currents of 3 OA or more. is deformed. In contrast, in the present invention, a conductive path (2) is formed on a metal substrate (1) with good heat dissipation, and a large current of about 4 OA is passed through a portion of the conductive path 2) for use as the detection resistor R0 (4). Even if it generates heat, it is immediately released.

Furthermore, as shown in FIG. 1, the present invention has a power semiconductor element (3), a detection resistor RO (4), and a diode <10) formed on a metal substrate (1). The substrate temperature becomes the same as that of (10), and it is possible to correct variations in resistance of the detection resistor R and (4) due to temperature changes.

That is, another feature of the present invention is that the diode (10) in the bridge circuit corrects the variation in resistance of the detection resistor R6 (4) due to temperature changes. The bridge circuit is formed as described above.

The operating principle of the temperature correction method using diodes will be explained below.

In Figure 2, the Zener voltage v2 at the Zener diode
(at this time, Ov is the anode side of the Zener voltage v2). Current 1. The midpoint voltage VllV of the bridge circuit when is flowing through the detection resistor R0 is given by the following equation.

The above equation (2) has a dependency on IE style I0, ? ! ! Style 1
．． When is large, the midpoint voltage V becomes a low voltage. Current I0
The midpoint voltage V, , V, when is small is V I < V *
Therefore, the current ■. When becomes a dog and reaches Io<&IAx>, the midpoint voltage V,,V, becomes equal to V,=V, and at this time, the output of the comparator is inverted and the current flow increases. is blocked.

The temperature change of the detection resistor R6 is as shown in FIG. 6, and when the temperature is 25° C., the resistance value is r. , and this can be expressed as the following formula.

Ro-roe (1+α(T-25)) ・-・
-・-・(3) Ro here. is the Cu pattern resistance value at 25° C., and α is the TCR of Cu. Expression (3) above is converted to (2)
By substituting into the equation, the temperature change by V is given as follows.

(4) The temperature change of the diode is as shown in FIG. 7. When the temperature is 25° C., the voltage (2) is VDO, which is expressed as the following equation.

Vb=Vood(T-25)...
-=(5) Here, β is the amount of temperature change of the P-N junction V, which is about -2 m' per one! //”C. Above (5)
By substituting equation (1) into equation (1), the temperature change of V is given as follows.

At a temperature of 25°C, l6 = midpoint at I@(MAX)'
71: EE V 1゜■ is equal to v1 V, so if the temperature change amount of the midpoint voltage V l, V * is the same, even if the temperature changes, the midpoint voltage V at 1° = Is<MAX> I=V* holds true.

First, if we differentiate equation (4) with respect to temperature T, then if we differentiate equation (6) with temperature, we get the midpoint 'WL pressure V, -V!' at a temperature of 25°C. can be expressed as follows.

When rearranged by ratio, a two-dimensional simultaneous equation is given as shown below.

Solving the equations (11) and (12) above gives the following equations.

becomes. Since equations (13) and (14) are initial constants, RA
IR8 is also determined by only one constant. Therefore (
13) As shown in equation (14), if RA and R11 are determined, the midpoint voltage V + "" V t will always be equal regardless of temperature changes, and as shown in Figure 8, it will remain constant regardless of temperature changes. Current can be detected.

(G) Effects of the Invention As detailed above, according to the present invention, a large current can be detected by using a portion of the conductive path formed on the metal substrate as a current detection resistor. Furthermore, it is possible to directly detect a large current flowing through a power semiconductor element, thereby helping to destroy the power semiconductor element.

Furthermore, in the present invention, even when a large current is applied, heat is sufficiently dissipated by the metal substrate, so that no deformation of the substrate occurs.

Further, according to the present invention, by providing a protrusion at the end of the detection resistor made of copper foil, the resistance of the detection resistor can be finely adjusted and a protection circuit can be easily formed.

Furthermore, in the present invention, complete temperature correction can be performed by providing a temperature (TCR) correction diode on the metal substrate.
Copper foil with a large CR can be fully utilized as a detection resistor.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line I-II in FIG. 1, FIG. 3 is a bridge circuit diagram used in the present invention, and FIG. 4 is a control diagram used in the present invention. Circuit diagram, Fig. 5 is a characteristic diagram regarding conductor width and fusing current, Fig. 6 is a temperature characteristic diagram of resistance, Fig. 7 is a temperature characteristic diagram of voltage, and Fig. 8 is a temperature characteristic diagram of detected current corrected by the present invention. FIG. 9 is a plan view showing another embodiment of the present invention, and FIG. 10 is a conventional bridge circuit diagram. (1)... Metal substrate, (2)... Conductive path, (3
)...power semiconductor element, (4)...detection resistor,
(5)...Insulating thin layer, (6)(7)(8)(9)
...Resistance R,, R1, R1, R1 (10)...Diode, (11)...Comparator, (12)...
Projection, (13)... Connection body, (14)... Slit, (15)... Wire, (16) (17)
(18) (19)...Transistor. Applicant: SANYO Electric Co., Ltd. and one other agent Patent attorney: Takuji Nishino Water 0 Figure 10

Claims (1)

[Claims] (1) A metal substrate with good thermal conductivity, a thin insulating layer provided on the metal substrate, a conductive path of a desired shape formed of copper foil on the thin insulating layer, and a conductive path fixed on the conductive path. a power semiconductor element for controlling the supply of power to a load; a low resistance detection resistor formed using a part of the conductive path extending near the power semiconductor element; A hybrid integrated circuit, comprising: detecting a current flowing through the power semiconductor element using the detection resistor.