JPH06224367A - Integrated circuit - Google Patents

Abstract

PURPOSE:To avoid reduction of impedance and maintain good absorption of an external surge voltage by forming the minimum gap between a first and a second metal films to be provided opposite the angled end part of one metal film. CONSTITUTION:An integrated circuit comprises an insulating substrate 12, a predetermined circuit including a first metal film 14 connected with an external wiring formed on this substrate 12 and a second metal film 15 of the ground potential and a resin provided on the substrate 12 to protect the predetermined circuit. The first metal film 14 and second metal film 15 are formed so that the angled end part 17 of at least one metal film 14 is provided opposite the other. Therefore, when an external surge voltage is applied to the first metal film 14, discharge occurs easily between the angled end portions 17, 18 of the first and second metal films 14, 15 and a discharge start voltage has a comparatively lower value. A greater part of the external surge voltage is absorbed by discharge between the angled end portions 17, 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated circuit having improved protection performance against external surge voltage.

[0002]

2. Description of the Related Art As is known in the art, in an integrated circuit such as a vehicle-mounted hybrid thick film integrated circuit, its external terminal has a voltage of 10 kV to 30 kV, such as an ignition spark from an ignition device. External surge voltage is applied, which may damage the circuit elements of the integrated circuit. Therefore, a large-capacity capacitor or Zener diode was connected to the external terminal so that the circuit element is protected from an external overvoltage including such an external surge voltage. There were problems such as increase and cost increase.

On the other hand, a bypass capacitor is inserted between the input and output terminals, which are external terminals, between the terminal and the ground potential portion in order to prevent external noise from entering the circuit. In order to absorb the external surge voltage applied to the terminal without adding another component, the bypass capacitor must use a bypass capacitor having a large capacity and a high withstand voltage. Therefore, the shape of the bypass capacitor becomes large,
This will reduce the space factor of the integrated circuit and increase the cost.

For this reason, there is one disclosed in Japanese Patent Publication No. 61-39742 which protects a circuit element without adding a separate component. Below, FIG. 12 and FIG.
This will be described with reference to FIG. 12 is a plan view and FIG.
Is a sectional view.

In the figure, reference numeral 1 is an integrated circuit, 2 is a pad portion connected to the external terminals 3 and circuit elements constituting a circuit on the substrate 4, and 5 is a predetermined distance from the pad portion 2, that is, It is a metal film having a ground potential and facing each other with a gap 6 therebetween. A high resistance film 7 is provided in the gap 6 so as to connect the pad portion 2 and the metal film 5. A resin 8 is coated on the entire substrate 4 to protect the circuit.

In such a structure, when an external surge voltage is applied to the pad portion 2 from the external terminal 3, most of the surge voltage is discharged to the metal film 5 at the ground potential through the high resistance film 7 in the gap 6 portion. , Circuit elements will be protected.

However, in the above-mentioned conventional technique, if the gap 6 between the pad portion 2 absorbing the external surge voltage and the metal film 5 is wide, the surge voltage is not sufficiently absorbed. Further, when the gap 6 is narrowed, it is possible to absorb a relatively low surge voltage, which has good protection characteristics in terms of protection of the internal circuit, but between the pad portion 2 and the metal film 5 at the ground potential. The impedance will decrease.

For example, the distance between the pad portion 2 and the metal film 5 is 0.
In the case of 4 mm, if a sheet resistance of 200 kΩ is provided between them, the impedance of the pad portion 2 and the metal film 5 becomes 50 kΩ to 60 kΩ, and even in the worst case, it is 30 kΩ.
Ω impedance can be secured. Then, when a surge voltage of 20 kV was applied between both of them and the absorption state of the surge energy was confirmed by 100 test pieces, the surge voltage was absorbed to less than 20%. It was

On the other hand, when the distance between the pad portion 2 and the metal film 5 is 0.3 mm and a sheet resistance of 200 kΩ is provided between them, a surge voltage of 20 kV is similarly applied between them. The surge energy absorption status 1
When confirmed with 00 test pieces, the probability that the surge voltage is absorbed reaches a high rate of 99%, but the impedance drops to about 15 kΩ, which adversely affects the operation of the internal circuit.

Further, in a circuit in which a resistor is inserted in an input terminal which is an external terminal, the resistance value accuracy in the state where the resistance is printed is only about ± 30%, and the accuracy value within several% is obtained. In order to obtain the resistance, a cut is made in the resistance and trimming is performed to obtain a predetermined resistance value. In such a circuit, when an external surge voltage is applied to the input terminal, even if the voltage is relatively low, the resistor may burn out and the operation of the circuit may not be restored.

From this point of view, therefore, it is necessary to reliably absorb a relatively low surge voltage.

[0012]

As described above, a high resistance film is provided between the conductor portion connected to the external terminal and the conductor portion of the ground potential, which is opposed to the conductor portion with a predetermined gap, to connect the conductor portion with a high resistance. Although an external surge is discharged through the film, reducing the gap size between both conductors causes a drop in impedance,
If the gap is widened, the absorption performance of the external surge voltage will deteriorate. The present invention has been made in view of such a situation, and the purpose thereof is not to reduce cost or space factor due to addition of another component,
An object of the present invention is to provide an integrated circuit which does not cause a decrease in impedance and which can favorably absorb an external surge voltage.

[0013]

An integrated circuit according to the present invention has an insulating substrate, a first metal film connected to an external wiring formed on the substrate, and a second metal film having a ground potential. In an integrated circuit including a predetermined circuit and a resin provided on a substrate so as to protect the circuit, the first metal film and the second metal film have a minimum gap between the metal films. It is characterized in that it is formed so that the corner point portions of at least one metal film are opposed to each other, and is connected to an insulating substrate and external wiring formed on this substrate. In an integrated circuit including a predetermined circuit having a first metal film and a second metal film having a ground potential, and a resin provided on a substrate so as to protect the circuit, the first metal film is The second metal film means that the minimum gap between these metal films is small. The angular tip portion of one of a metal film is formed so as to be opposed, and a first minimized gap
And a high-resistance film is provided between the two metal films so as to connect the second metal film, and further, the insulating substrate and the external wiring formed on the substrate are connected. A predetermined circuit having a first metal film and a second metal film having a ground potential, a capacitor inserted between the first metal film and the second metal film of the circuit, and the circuit. In an integrated circuit provided with a resin provided on a substrate so as to protect, a capacitor is provided with an electrode provided on an outer surface of both end portions connected to the first metal film and the second metal film of the capacitor. It is characterized in that at least a part thereof has a narrow interval portion which becomes a discharge gap for protecting the circuit against an external surge voltage.

[0014]

In the integrated circuit configured as described above, the first metal film connected to the external wiring and the second metal film having the ground potential have the minimum gap between the metal films of at least one metal. When the external surge voltage is applied to the first metal film by the configuration in which the apex portions of the film are made to face each other, between the apex portions of the first and second metal films, Discharge is easy to start, and the discharge start voltage has a relatively low value. Then, most of the external surge voltage is absorbed by the discharge between the apex portions. Furthermore, since there are few portions where both metal films face each other with a minimum gap, the impedance between both metal films becomes large.

Further, the capacitor inserted between the first metal film connected to the external wiring and the second metal film at the ground potential is the first metal film and the second metal film of the capacitor. By having a configuration in which at least a part of the electrodes provided on the outer surfaces of both end portions connected to is provided with a narrow gap portion that serves as a discharge gap for protection of the internal circuit against an external surge voltage,
When an external surge voltage is applied to the first metal film, discharge is started in the narrow gaps of the electrodes provided on the outer surfaces of both ends of the capacitor, and most of the external surge voltage is generated by the discharge in the narrow gaps of the electrodes. Be absorbed.

Therefore, there is no increase in cost or reduction in space factor due to the addition of another component, no decrease in impedance is caused, and the external surge voltage can be absorbed well.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. 1 is a plan view of a main part, FIG. 2 is a sectional view taken along the line AA in FIG. 1, FIG. 3 is a characteristic diagram of a surge protection rate, and FIG. 4 is a characteristic diagram of impedance. 5 is a plan view of a main part of the modified example.

In FIGS. 1 and 2, the integrated circuit 11 has Ag-Pt or Ag-Pt on the upper surface of a substrate 12 formed of a ceramic insulating material such as Al ₂ O _3.
A predetermined circuit pattern is printed with a conductive paste of Pd, and circuit elements are connected, for example. The printed circuit pattern is provided with a strip-shaped first metal film 14 to which the external terminals 13 are connected and a strip-shaped second metal film 15 having the same ground potential.

The first metal film 14 and the second metal film 15 are arranged such that their end portions are parallel to each other, and the minimum gap between them, that is, the gap 16 is equal to that of both metals. Right-angled corner portion 1 at the end of the membranes 14 and 15
It is provided so as to face each other. The size of the gap 16 is 0.3 mm
It is set to a predetermined size selected within a range of about 0.5 mm.

A high resistance film 19 is formed in the gap 16 so as to form a sheet resistance of 100 kΩ or more, for example, 200 kΩ between the end portions of the first and second metal films 14 and 15 on the upper surface of the substrate 12. This high resistance film 1 is provided
9 connects the both corner portions 17 and 18.

Then, the substrate 12 is housed in a case (not shown), and the entire substrate 12 is covered with a resin 20 such as silicon gel having a high withstand voltage for measures against moisture resistance or the like to form the integrated circuit 11. .

According to the present embodiment configured as described above,
When an external surge voltage is applied to the external terminal 13 and the potential of the first metal film 14 rises, the gap 16 is provided between the first metal film 14 and the first metal film 15 facing the corner portion 18 of the second metal film 15 at the ground potential.
The potential gradient at the corner portion 17 of the metal film 14 becomes large,
Most of the surge voltage is discharged through the high resistance film 19 between the both corner portions 17 and 18 forming the minimum gap portion. In this way, the internal circuit and circuit elements are protected from external surge voltage.

Regarding the state of absorption of surge energy in the gap 16, the gap size is 0.3 mm,
It was changed to 0.4 mm and 0.5 mm, respectively, and confirmed by 100 test pieces. As a result, the horizontal axis shows the gap size and the vertical axis shows the surge protection rate, and as shown by the solid line in FIG. A very high surge protection rate of% was obtained. The broken line is the result of the conventional technique. A surge protection rate close to 100% can be obtained with a gap size of 0.3 mm, but a very low value is obtained with 0.4 mm and 0.5 mm.

At the same time, the impedance between the first metal film 14 and the second metal film 15 at the ground potential was measured. The horizontal axis represents the gap size and the vertical axis represents the impedance. As shown in, even with a gap size of 0.3 mm, a high impedance value of 60 kΩ was obtained. On the other hand, according to the result of the conventional technique indicated by the broken line, the gap size of 0.3 mm is as low as 15 kΩ.

As described above, according to this embodiment, the impedance between the first metal film 14 and the second metal film 15 is
When the gap size is as wide as 0.5 mm, it is very high, 120 kΩ or more. In addition, the gap size is 0.
Even when the width is as narrow as 3 mm, a sufficiently high impedance of 60 kΩ can be secured, and the surge energy absorption at this time is absorbed at a high level as indicated by the surge protection rate.

Therefore, even when a lower external surge voltage is applied, the surge voltage can be absorbed better than in the conventional case. For example, the resistor is trimmed in the circuit in which the resistor is inserted in the external terminal. However, there is less risk that the discharge that reliably absorbs the surge voltage occurs between the first metal film 14 and the second metal film 15 and the resistance is burned.

Further, since surge energy can be sufficiently absorbed without adding a separate component such as a capacitor or a Zener diode to the external terminal 13, the addition of the separate component may cause an increase in cost and a reduction in space factor. Absent.

Although the high resistance film 19 is provided in the gap 16 and the two corner portions 17 and 18 are connected to each other by the high resistance film 19, instead of the high resistance film 19, the gap 16 has a higher withstand voltage than the resin 20. A low insulating film may be provided, or only the resin 20 may be provided, and the selection may be appropriately made in consideration of the influence on the circuit operation and the level of the external surge voltage to be absorbed.

FIG. 5 is a plan view of an essential part of a modified example of the first embodiment, in which the first metal film 22 on which the external terminals 13 of the integrated circuit 21 are provided and the second metal of the ground potential. Membrane 23
Means that each is formed in a strip shape and its end portions are provided so as to intersect at right angles on the extension of the arrangement direction, and the right angle corner portions 24 and 25 of the respective end portions are opposed to each other.
Gap 1 which is the minimum gap between both corners 24 and 25
6 is formed. And in the part of the gap 16,
A high resistance film 19 is provided so as to connect between the end portions of both metal films 22 and 23.

Even in the integrated circuit 21 thus constructed, the same operation and effect as those of the first embodiment can be obtained.

Next, a second embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a plan view of a main part, and FIG. 7 is a plan view of a main part of a modified example.

In FIG. 6, the integrated circuit 26 is formed by printing a predetermined circuit pattern on the upper surface of the substrate 12 with a conductive paste and connecting circuit elements. The printed circuit pattern is provided with a strip-shaped first metal film 27 to which the external terminals 13 are connected and a strip-shaped second metal film 28 having the same ground potential.

The first metal film 27 and the second metal film 28 are arranged such that their respective end portions face each other on the same line, and one end portion of each end portion is cut off so as to reach the end portion. Acute-angled tip portions 29 and 30 are formed. And the minimum gap between both metal films 27, 28,
That is, the gap 16 is a sharp end portion 2 of the end portion.
The gap 1 is formed by making 9 and 30 face each other.
The size of 6 is set to a predetermined size selected within the range of about 0.3 mm to 0.5 mm.

A high resistance film 19 is formed in the gap 16 so as to form a sheet resistance of 100 kΩ or more, for example, 200 kΩ on the upper surface of the substrate 12 between the end portions of the first and second metal films 27 and 28. This high resistance film 1 is provided
9 connects between the two tip portions 29, 30.

The substrate 12 is housed in a case (not shown), and the entire substrate 12 is covered with a resin such as silicon gel having a high withstand voltage for measures against moisture resistance or the like to form the integrated circuit 26.

According to the present embodiment configured as described above,
When an external surge voltage is applied to the external terminal 13, the opposite tip portions 2 of the gap 16 forming the minimum gap
Most of the surge voltage is discharged through the high resistance film 19 between 9 and 30. This protects the internal circuits and circuit elements from external surge voltages.

In this embodiment, the tip portion 2
First and second metal films 27 facing each other with 9, 30
Since the terminating portions of 28 have the same arranging direction, they can be formed with the same arranging pitch as the other adjacent wiring portions, and it is not necessary to provide an extra space, and the first embodiment is also possible. The same action and effect as can be obtained.

FIG. 7 is a plan view of an essential part of a modified example of the second embodiment, in which the first metal film 32 provided with the external terminal 13 of the integrated circuit 31 and the second metal film at the ground potential. 33 is formed in a strip shape, and the end portions thereof are arranged so as to face each other on the same line, and both end portions of the end portions are cut off so that the end portions 34, 35 are provided at the end portions.
Are formed. The minimum gap between the metal films 32 and 33, that is, the gap 16 is the tip end portion 3 of the end portion.
It is formed so that 4, 35 face each other. A high resistance film 19 is provided in the gap 16 so as to connect between the end portions of the metal films 22 and 23.

Even in the integrated circuit 31 thus constructed, the same operation and effect as those of the second embodiment can be obtained.

Next, a third embodiment will be described with reference to FIGS. 8 is a cross-sectional view of a main part, FIG. 9 is a perspective view of a capacitor, and FIG. 10 is a perspective view of a modified capacitor.

In FIGS. 8 and 9, the integrated circuit 36 is formed by printing a predetermined circuit pattern on the upper surface of the substrate 12 with a conductive paste and connecting circuit elements. The printed circuit pattern is connected to an external terminal 37 and an internal circuit.
A metal film 38 and a second metal film 39 having a ground potential. Then, the first metal film 38 and the second metal film 39
A bypass capacitor 40 for bypassing the noise signal is connected between the two.

The bypass capacitor 40 is a monolithic ceramic capacitor having a rectangular parallelepiped shape and its capacitor body 41.
Is an electrode 4 in which the electrode plates alternately laminated inside are conductive.
2, 43 are Ag-Pt on the outer surfaces of the opposite ends of the capacitor body 41 so as to enable surface mounting on the substrate 12.
The conductive paste is formed by dipping or the like.

Further, the electrodes 42, 43 on at least one surface of the capacitor body 41 are provided with projections 45, 46 which partially project in the opposite electrode direction and form a gap 44 at the tips of the electrodes. There is. Note that the gap 44
The size of 0.3mm ~ 0.5 so that it discharges at a predetermined voltage
It is set to a predetermined size selected within a range of about mm.

Then, the substrate 12 is housed in a case (not shown), and the entire substrate 12 is covered with a resin 20 such as silicon gel having a high withstand voltage for measures against moisture resistance and the like, whereby the integrated circuit 36 is formed. .

According to the present embodiment configured as described above,
Of the signals applied to the external terminal 37, the noise signal is bypassed to the second metal film 39 at the ground potential by the bypass capacitor 40, and the required signal is transmitted to the internal circuit through the first metal film 38.

When an external surge voltage is applied to the external terminal 37 and the potential of the first metal film 38 rises, the potential of the convex portion 45 of the electrode 42 provided on the surface of the capacitor body 41 also rises. Then, the potential gradient between the convex portion 45 of the electrode 42 and the convex portion 46 of the electrode 43 at the ground potential, which is opposed with the gap 44 provided therebetween, becomes large, and most of the surge voltage through the resin 20 is discharged in the gap 44. Be seen. In this way, the bypass capacitor 40 and the internal circuit are protected from the external surge voltage.

As described above, according to this embodiment, the external surge voltage is absorbed by the discharge in the gap 44 between the convex portions 45 and 46 of the electrodes 42 and 43 provided on the outer surface of the capacitor body 41 of the bypass capacitor 40. Is done. Therefore, it is not necessary to use, as the bypass capacitor 40, a capacitor having a large capacity and a high withstand voltage and having a large shape and a high price.

Then, the bypass capacitor 40 is connected to the substrate 1
Even when it is surface-mounted on No. 2, it does not occupy a large area or a large volume, so it can be integrated into a small size, and sufficient surge energy can be absorbed without adding a separate part such as a Zener diode to the external terminal 37 Therefore, the cost increase and the space factor decrease due to the addition of other parts are not caused.

The resin 20 covering the substrate 12 is provided in the gap 44 portion. However, an insulating film having a lower withstand voltage than the resin 20 is provided in the gap 44 portion within a range that does not hinder the circuit operation. Alternatively, a high resistance film may be provided.

FIG. 10 is a perspective view of a capacitor of a modification of the third embodiment. This modification has the same configuration as that of the third embodiment except for the capacitor, and the different points will be described below.

In FIG. 10, the bypass capacitor 47
Is a rectangular parallelepiped monolithic ceramic capacitor, and the electrodes 4 are formed on the outer surfaces of the opposite ends of the capacitor body 48.
9, 50 are formed by dipping a conductive paste or the like so as to enable surface mounting on the substrate. The electrodes 49, 50 on at least one surface of the capacitor body 48 are provided with projections 51, 52 such that a part of the electrodes 49, 50 project in the direction of the opposing electrodes.

These convex portions 51, 52 are formed with a gap 55 by facing right angled corner portions 53, 54 of the tip portions.
The size of the gap 55 is set to a predetermined size selected within a range of about 0.3 mm to 0.5 mm so as to discharge at a predetermined voltage.

With this structure, the corner portions 53 and 54 face each other to form the gap 55, so that the discharge property of the gap 55 is improved and the same action and effect as those of the third embodiment are obtained. To be

Next, a fourth embodiment will be described with reference to FIG. FIG. 11 is a perspective view of a capacitor, and this embodiment has the same structure as the third embodiment except for the capacitor, and the different points will be described below.

In FIG. 11, the bypass capacitor 56
Is a monolithic ceramic capacitor having a rectangular parallelepiped shape, and electrodes 5 are provided on the outer surfaces of the opposite ends of the capacitor body 57.
8, 59 are formed by dipping a conductive paste or the like so as to enable surface mounting on the substrate.

These electrodes 58 and 59 have the same gap 60 with their ends facing each other over a long range of the outer surface of the capacitor body 55, for example, over the entire circumference. Note that the gap 6
The size of 0 is 0.3 mm to 0.
It is set to a predetermined size selected within a range of about 5 mm.

With this structure, in this embodiment, even if the shape of the capacitor body 57 is very small, it is not necessary to form a complicated electrode pattern when forming the discharge gap against the external surge voltage. The processing is simple, and the same action and effect as the third embodiment can be obtained.

The present invention is not limited to the above-described embodiments, but can be implemented with appropriate modifications within the scope of the invention.

[0060]

As is apparent from the above description, the present invention does not cause a cost increase or a space factor decrease due to the addition of another component, does not cause a decrease in impedance, and absorbs an external surge voltage. It is possible to obtain an effect such as good effect.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a characteristic diagram of a surge protection rate according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram of impedance according to the first embodiment of the present invention.

FIG. 5 is a plan view of an essential part of a modified example of the first embodiment of the present invention.

FIG. 6 is a plan view of an essential part showing a second embodiment of the present invention.

FIG. 7 is a plan view of an essential part of a modified example of the second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a main part showing a third embodiment of the present invention.

FIG. 9 is a perspective view of a capacitor according to a third embodiment of the present invention.

FIG. 10 is a perspective view of a capacitor according to a modification of the third embodiment of the present invention.

FIG. 11 is a perspective view of a capacitor according to a fourth embodiment of the present invention.

FIG. 12 is a plan view showing a conventional example.

13 is a cross-sectional view of FIG.

[Explanation of symbols]

 12 ... Substrate 13 ... External terminal 14 ... First metal film 15 ... Second metal film 16 ... Gap 17,18 ... Corner portion 19 ... High resistance film 20 ... Resin

Claims (3)

[Claims] 1. A predetermined circuit having an insulating substrate, a first metal film connected to an external wiring formed on the substrate, and a second metal film having a ground potential, and a circuit for protecting the circuit. In the integrated circuit including a resin provided on the substrate, the first metal film and the second metal film have a minimum gap between the metal films at a corner point portion of at least one metal film. An integrated circuit characterized by being formed so as to face each other. 2. A predetermined circuit having an insulating substrate, a first metal film connected to an external wiring formed on the substrate, and a second metal film having a ground potential, and a circuit for protecting the circuit. In the integrated circuit including a resin provided on the substrate, the first metal film and the second metal film have a minimum gap between the metal films at a corner point portion of at least one metal film. Integrated with each other, and a high resistance film is provided between the metal films so as to connect the first and second metal films to the minimum gap portion. circuit. 3. A predetermined circuit having an insulating substrate, a first metal film connected to external wiring formed on the substrate, and a second metal film having a ground potential, and the first circuit of the circuit. A capacitor inserted between the second metal film and the metal film of
In an integrated circuit comprising a resin provided on the substrate so as to protect the circuit, the capacitor has an outer surface at both ends thereof connected to the first metal film and the second metal film of the capacitor. At least a part of the electrodes provided in
An integrated circuit having a narrow gap portion serving as a discharge gap for protecting the circuit against an external surge voltage.