JP3240575B2 - Solid state relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid state relay. Specifically, the present invention relates to a solid state relay using a MOSFET.

[0002]

2. Description of the Related Art In recent years, a solid state relay (hereinafter, referred to as "SSR") using a MOSFET has been developed as a non-contact relay having a long life and suitable for high-speed and high-frequency switching. Two power MOSs as one of this SSR
Some FETs (hereinafter referred to as "MOSFETs") are connected in anti-series between source electrodes to cope with both AC / DC output loads. FIG. 9 shows the principle of operation. The light emitting element 52 converts an input signal input from the input terminals 60, 60 into an optical signal, and emits the light signal to the light receiving element 53. When the light receiving element 53 receives the optical signal, the light receiving element 53 converts the light signal into an electric signal, and converts the signal into an electric signal.
a, and a negative voltage is applied to the gate electrode 56b of the second MOSFET 55b. Gate electrodes 56a, 56
When a negative voltage is applied to the first MOSFET 55a
A current path is opened between the source electrode 58a and the drain electrode 59a of the second MOSFET 55b and between the source electrode 58b and the drain electrode 59b of the second MOSFET 55b.

When the input terminals 60 and 60 are turned on in a state where a positive load is applied to the drain electrode 59a in the first MOSFET 55a, a negative voltage is applied to the first gate electrode 56a. 1 drain electrode 59
a → first source electrode 58a → second diode 57b
→ Current flows to the second drain electrode 59b, and the portion between the output terminals 61 is turned ON. Further, with a positive load applied to the second drain electrode 59b, the input terminals 60, 6
When the interval between 0 and 0 is turned on, a negative voltage is applied to the second gate electrode 56b, and a current flows from the second drain electrode 59b to the second source electrode 58b to the first diode 57a to the first drain electrode 59a. Flows, and the output terminals 61 are turned on. Therefore, by electrically turning on and off the input terminals 60, 60, the output terminals 61, 61 can be turned on and off regardless of the load of AC / DC.
FF control can be performed. In the figure, reference numeral 54 denotes a turn-off circuit, which is a circuit for shortening the turn-off time of the MOSFETs 55a and 55b.

FIG. 10 shows a conventional SSR5.
FIG. 3 is a plan view showing an example of the structure of FIG. 1, in which a light emitting element 52 and a light receiving element 53 are sealed with a transparent sealing resin 62 such as silicon gel to efficiently transmit an optical signal by reflecting the light signal at an interface; Two MOSFETs 55a,
A pair of input terminal leads 63a, 63b and a pair of output terminal leads 64a, 64b are drawn out of the exterior resin portion 65 together with the resin 55. This SSR 51 is a lead frame 6
6, and the lead frame 66 is provided with input terminal leads 63a and 63a as shown in FIG.
63b, output terminal leads 64a and 64b, MOSFE
The die pads 67a, 67b, 67c for mounting the T55a, 55b and the light receiving element 53, and a pair of relay leads 68a, 68b are processed into a predetermined pattern.

In order to form the SSR 51, first, as shown in FIG. 11, a light emitting element 52 such as an LED is die-bonded to one input terminal lead 63a, and the light receiving element 53 such as a photodiode is arranged in parallel with the light emitting element 52. Is die-bonded on the die pad 67c. The die pad 67
The drain electrodes 59a and 59b of the MOSFETs 55a and 55b are die-bonded on a and 67b, respectively. Next, the light emitting element 52 and the remaining input terminal lead 63b are connected to the gold wire 69.
After bonding between the terminals of the light receiving element 53 and the relay leads 68a and 68b with the gold wire 69, the light emitting element 52 and the light receiving element 53 are sealed with the sealing resin 62. Also, a relay lead 68a and two MOSFEs
Aluminum wires 70 are bonded between the gate electrodes 56a and 56b of T55a and 55b, and aluminum wires 70 are bonded between the relay leads 68b and the source electrodes 58a and 58b. In this manner, the light emitting element 52, the light receiving element 53, and the two MOSFETs 55a and 55b are mounted on the lead frame 66 so as to be substantially aligned with each other. The SSR 51 can be manufactured separately from the lead frame 66.

[0006]

At this time, the relay leads 68a and 68b and the two MOSFETs 55a and 55b
For the aluminum wire 70 used for wire bonding, a thick aluminum wire or a plurality of aluminum wires were used in order to minimize wiring resistance.

However, the two MOSFETs 55
Since each of the source electrodes 58a and 58b and the relay lead 68b is wire-bonded by an aluminum wire 70, the electrical resistance between the source electrode 58a and the source electrode 58b is two aluminum wires 70a and 55b. And the sum of the electric resistance of the relay lead 68b, which is considerably large. For example, if the diameter is 200
When using an aluminum wire 70 μm, an aluminum wire 1 mm
Since the relay lead 68b is made of copper, even if the resistance is neglected, if the length of the all-aluminum wire 70 between the source electrode 58a and the source electrode 58b is 20 mm, both of them can be used. The resistance value of the aluminum wire 70 between them is 12 mΩ. Therefore, if the source electrode 58
1.2 W when a current of 10 A flows between a and 58b
The amount of heat generated is required, and the use conditions such as the heat radiation from the SSR 51 and the ambient temperature have to be considered. Also, the electric resistance between the gate electrodes 56a and 56b becomes considerably large similarly, resulting in an increase in the heat generation of the SSR 51 as a whole.

Further, the respective terminals of the light receiving element 53 and the respective relay leads 68a, 68b are wire-bonded with gold wires 69, respectively. Therefore, each of the relay leads 68a, 68b for wire bonding the gold wire 69 is used.
Has to be plated with a good bonding property with the gold wire 69, such as gold plating, so that the manufacturing process is complicated and the manufacturing cost is increased.

Further, two MOSFETs 55a and 55
b indicates that the drain electrodes 59a and 59b are directly
Since the die pads are mounted on the bases 7a and 67b by die bonding, there is a risk of electric shock if the side surface of the die pad opposite to the output terminal leads 64a and 64b is exposed from the exterior resin part 65. For this reason, the die pads 67a, 67b, 67 are provided so that the side surfaces of the die pad are not exposed to the outside.
c was separated from the outer frame 66a of the lead frame (see FIG. 11). As a result, for example, when the MOSFET 55b is mounted on the die pad 67b,
As shown in FIG. 12A, the lead frame 66 is deformed due to the weight, and the die pad 67b is inclined.
It was difficult to perform wire bonding. In particular, it was more remarkable as the thickness of the lead frame 66 was reduced to 0.5 mm or less and the thickness of the lead frame 66 was reduced. Even if the lead frame 66 is corrected for deformation and the die pad 67b is returned to a horizontal state and wire-bonded, the lead pad 66b is deformed again during transportation to the next step, and as shown in FIG. The aluminum wire 70 and the gold wire 69 bonded are cut or molded while being inclined,
There is also a problem that the yield of the SSR 51 is deteriorated.

Further, the SSR 51 has a planar coupler structure in which the light-emitting element 52 and the light-receiving element 53 are arranged on the same plane, so that light transmission efficiency is poor. In some cases, the light emission amount is increased by using the element 52. For example, another light emitting element 52 is mounted on the mounting lead 72 like the SSR 71 shown in FIG. 13, and the light emitting element 52 on the input terminal lead 63a and the mounting lead 72 are connected by the gold wire 69. Bonding. At this time, as shown in FIG. 14A, a light emitting element 52 of the same type, for example, an N side-up type light emitting element 52
The P side of the light emitting element 52 is die-bonded to the input terminal lead 63a and the mounting lead 72, respectively, and the N side of the light emitting element 52 and the mounting lead 72 on the input terminal lead 63a are connected by a gold wire 69. By bonding and bonding the N side of the light emitting element 52 on the mounting lead 72 and the remaining input terminal lead 63b with the gold wire 69, the two light emitting elements 52 are connected in series as shown in FIG. I was connected. For this reason, the mounting leads 72 for mounting the light emitting elements 52 must be plated with gold or the like. As the number of the light emitting elements 52 increases, the number of mounting leads 72 to be plated increases, and the manufacturing process becomes troublesome. As it became more expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to reduce the amount of heat generated, reduce manufacturing costs, and provide a highly reliable solid state relay. To provide.

[0012]

According to the present invention, there is provided a solid state relay comprising: a light emitting portion for switching between a light emitting state and a light extinguishing state; a light receiving portion for receiving light emitted from the light emitting portion;
A first semiconductor switching element and a second semiconductor switching element that perform a switching operation by photovoltaic power generated in the light receiving unit; and the light receiving unit, the first semiconductor switching element, and the second semiconductor switching element An electrode of the first semiconductor switching element and an electrode of the second semiconductor switching element electrically connected to an electrode of the light receiving portion in a solid state relay mounted and molded substantially in a line on a lead frame. Is directly wire-bonded.

Further, it is preferable that the electrode of the light receiving section and the electrode of the first semiconductor switching element are directly wire-bonded.

[0014] The light-emitting section may include at least one or more P-side up semiconductor light-emitting devices and at least one or more N-side semiconductor light-emitting elements.
A side-up semiconductor light-emitting device, and the P-side-up semiconductor light-emitting device mounted on a lead portion.
The N side of the N side up semiconductor element mounted on the side and another lead portion can be directly wire-bonded.

Further, the lead frame is provided with an insulative lead supporting portion for supporting at least a lead portion for mounting the first semiconductor switching element and a lead portion for mounting the second semiconductor switching element. It may be that.

[0016]

According to the solid state relay of the present invention, the electrode of the first semiconductor switching element and the electrode of the second semiconductor switching element electrically connected to the electrode of the light emitting section are directly wire-bonded. In addition, the wire length to be connected can be reduced as compared with the case where the electrode of the light emitting unit and the electrode of each semiconductor switching element are bonded. For this reason, the wiring resistance of the wire is reduced, and heat generated by the wire can be suppressed. Also,
Since the number of bonding locations is reduced, poor connection at the bonding locations is reduced, and the reliability of the solid state relay can be improved.

Further, by directly performing wire bonding between the electrode of the light emitting section and the electrode of the first semiconductor switching element, the wire length can be further shortened to further reduce wiring resistance and heat generation.

Further, since the P side of the P side up semiconductor light emitting device mounted on the lead portion and the N side of the N side up semiconductor light emitting device mounted on the other lead portion are directly wire-bonded, two or more In the case where the light emitting element is used, it is not necessary to wire-bond the electrode of the light emitting element to a lead portion on which another light emitting element is mounted. Therefore, the number of bonding portions and the number of lead portions to be plated are reduced, and the light emission amount can be increased at a low manufacturing cost.

Further, since the lead frame is provided with an insulative lead supporting portion for supporting two lead portions on which the semiconductor switching element is mounted, the lead portion on which the semiconductor switching element is mounted is horizontal with the lead frame without bending. And the wire connecting the two semiconductor switching elements and the wire connecting the light receiving unit and the semiconductor switching element can be sealed and molded without being cut. Of course, even if the lead supporting portion is exposed on the side surface of the solid state relay, it is insulative, so that touching that portion does not cause an electric shock. Also,
The semiconductor switching element is not damaged by surge current or the like flowing into the semiconductor switching element.

[0020]

FIG. 1 is a plan view showing a solid state relay 1 according to an embodiment of the present invention. 2
Is a light emitting element such as an LED, 3 is a light receiving element such as a photodiode, and 5a and 5b are output terminal leads 7a and 7 based on electric signals output from the light receiving element 3, respectively.
a power MOSFET that performs ON-OFF control between the light emitting element b and the light emitting element 2 and the light receiving element 3 are covered with a transparent sealing resin 4 such as silicon gel;
The two MOSFETs 5a and 5b are integrally molded with resin to form a pair of input terminal leads 6.
a, 6b and a pair of output terminal leads 7a, 7b are drawn out of the exterior resin portion 14. The light emitting element 2 is die-bonded to one input terminal lead 6a, and the upper surface electrode of the light emitting element 2 and the other input terminal lead 6b are bonded by a gold wire 8. The light receiving element 3 is die-bonded on the die pad 9c, and the cathode 3a and the relay lead 10a of the light receiving element 3 and the anode 3b and the relay lead 10
b are bonded by gold wires 8 respectively. Relay lead 10a and source electrode 1 of first MOSFET 5a
The source electrode 11b of 1a and the second MOSFET 5b is bonded by one aluminum wire 12 (so-called stitch bonding). Of course, using two aluminum wires 12, between the relay lead 10a and the source electrode 11a of the MOSFET 5a, the source electrode 1 of the MOSFET 5a
1a and the source electrode 11b of the MOSFET 5b may be bonded to each other. Similarly, the anode 3b of the light receiving element 3 is also connected to the relay lead 10b, the gate electrode 13a of the first MOSFET 5a, and the second MOS transistor.
The gate electrode 13a of the FET 5a is also bonded by one aluminum wire 12.

In this SSR1, the first MOSF
Source electrode 11a of ET5a and second MOSFET 5b
Is directly wire-bonded to the source electrode 11b of the second MOSFET 5b, as compared with a conventional case in which wire bonding is performed between the relay lead 10a and the source electrode 11b of the second MOSFET 5b. Can be shortened, for example, the length can be reduced to about 1/3. Therefore, the wiring resistance of the aluminum wire 12 is reduced, and the amount of heat generated by the aluminum wire 12 can be reduced. Also, MOSFET
Even if a MOSFET with a small on-resistance is used in order to reduce the residual voltage (voltage drop generated when ON control is performed), the conventional SSR 51 generates a large amount of heat from an aluminum wire and uses a MOSFET with a small on-resistance. Effect was not sufficiently obtained. Therefore, shortening the aluminum wire 12 necessary for wiring as in the present invention is extremely effective for an SSR using a MOSFET with a small on-resistance.

Further, in the SSR 1, the number of bonding portions is reduced, and the reliability can be improved by simplifying the manufacturing process and reducing the connection failure.

FIG. 2 is a plan view showing the structure of an SSR 21 according to another embodiment of the present invention. In the SSR 21, two light emitting elements 2 of an N side up light emitting element 2a and a P side up light emitting element 2b are used to increase the transmission efficiency of an input signal. For example, as shown in FIG. 3A, the P side of the N side up light emitting element 2a is die-bonded on the input terminal lead 6a, and the N side of the P side up light emitting element 2b is mounted on the other input terminal lead 6b. The side is die-bonded. The N-side and P-side up light emitting elements 2a of the N side up light emitting element 2a
The P side of FIG. 3B is bonded by a gold wire 8, and FIG.
As shown in (b), the N side up light emitting element 2a and the P side up light emitting element 2b are connected in series. As described above, by wire bonding the N side of the N side up light emitting element 2a and the P side of the P side up light emitting element 2b, the two light emitting elements 2a and 2b are connected in series without providing the mounting lead 72. be able to. Therefore, the plating process can be omitted, and the manufacturing cost can be reduced. In addition, since the number of bonding locations is reduced, light emission failure due to connection failure is reduced, and reliability can be further improved.

In the second embodiment, the light receiving element 3
Between the cathode 3a of the first MOSFET 5a and the source electrode 11a of the first MOSFET 5a is directly bonded with the gold wire 8, and between the anode 3b of the light receiving element 3 and the gate electrode 13a of the first MOSFET 5a is directly bonded with the gold wire 8. I have. As described above, if the light receiving element 3 and the first MOSFET 5a are directly wire-bonded without providing the relay leads 10a and 10b, the length of the aluminum wire 12 can be further reduced to reduce the heat generation. Further, since the relay leads 10a and 10b become unnecessary, the manufacturing cost can be reduced, and the size of the SSR 21 can be reduced.

When three or more light emitting elements 2 are used, the N side up light emitting element 2a and the P side up light emitting element 2b are combined to form the N side up light emitting element 2b.
The light emitting element 2 can also be connected in series by wire bonding between the N side of a and the P side of the P side up light emitting element 2b. For example, when four light emitting elements 2 are used, as shown in FIG. 4A, the P side of the N side up light emitting element 2a is die-bonded to one input terminal lead 6a, and the mounting lead 15 is N side of P side up light emitting element 2b and P of N side up light emitting element 2a
Die bond each side. The N-side of the P-side up light emitting element 2b is die-bonded to the remaining input terminal lead 6b. Then, the N side of the N side up light emitting element 2a on the input terminal lead 6a and the P side of the P side up light emitting element 2b on the mounting lead 15 are bonded with a gold wire 8, and the N side on the mounting lead 15 is bonded. N side of up light emitting element 2a and lead 6b for input terminal
A gold wire 8 is connected to the P side of the upper P side up light emitting element 2b.
4B, four light emitting elements 2a, 2b, 2a, 2b can be connected in series as shown in FIG.

FIGS. 5A and 5B are a plan view and a side view, respectively, of an SSR 31 according to still another embodiment of the present invention. The die pad 9a on which the first MOSFET 5a is mounted and the die pad 9a are shown. The die pad 9b on which the two MOSFETs 5b are mounted and the die pad 9c on which the light receiving element 3 is mounted are supported by lead support members 16, respectively. The SSR 31 can be easily manufactured by using a lead frame 17 as shown in FIG. The lead frame 17 has a lead 6 for an input terminal.
a, 6b, die pads 9c for mounting output terminal leads 7a, 7b and light receiving element 3, and MOSFETs 5a, 5b.
The die pads 9a, 9b and the like for mounting b are processed into a predetermined pattern. Also, three die pads 9
c, 9a, 9b and the lead frame outer frame 17a, the lower surfaces of the die pads 9c, 9a, 9b are supported by the lead frame outer frame 17a, and an insulating lead support member such as a polyimide film is used. 16 are provided. At predetermined positions on the lead frame 17, the light emitting elements 2a and 2b, the light receiving element 3, two MOSFs
The ETs 5a and 5b are mounted. Next, the light emitting elements 2a and 2b
After covering the light receiving element 3 with the sealing resin 4, the light emitting element 2, the light receiving element 3 and the two MOSFs are formed as shown in FIG.
The ETs 5a and 5b are integrally molded by sealing, and finally, the exterior resin portion 14 is separated from the lead frame 17, whereby the SSR 31 shown in FIG. 5 can be manufactured.

As described above, the three die pads 9a, 9
b and 9c are supported by the lead frame outer frame 17a by the lead supporting member 16, so that the light receiving element 3 and the MOS
The FETs 5a and 5b are connected to die pads 9c, 9a and 9 respectively.
b, the die pads 9c, 9a, 9b
, And the light emitting element 2 and the MOSFETs 5a and 5b can be held horizontally with the lead frame 17. Therefore, wire bonding can be easily performed using the gold wire 8 or the aluminum wire 12, and disconnection of the gold wire 8 or the aluminum wire 12 can be prevented, and the yield of the SSR 31 can be improved. Further, when the exterior resin portion 14 is cut off from the lead frame 17, the cut of the lead support member 16 is exposed on the side surface of the exterior resin portion 14. However, since the lead support member 16 is insulative, even if the cut is touched. There is no electric shock, and the MOSFETs 5a and 5b are not damaged by the surge current flowing from the cut.

FIG. 8 is a side structural view of an SSR 41 according to still another embodiment of the present invention. The lead support member 16 is provided on almost the entire lower surface of the die pads 9a, 9b, 9c. The support member 16 is sealed and formed so that the lower surface is exposed. If the lead supporting member 16 is made of a material having good heat conductivity such as aluminum nitride (AlN) or silicon carbide (SiC), the lead supporting member 16 functions as a heat radiating plate,
Heat generated from the ETs 5a and 5b can be efficiently released, and a more reliable SSR 41 can be provided.

[0029]

According to the solid state relay of the present invention, the wire connecting the electrodes of the two semiconductor switching elements can be shortened, so that the wiring resistance and heat generation by the wire can be reduced.

Further, by directly wire bonding the light receiving section and the electrode of the first semiconductor switching element,
Since the wire connecting the light receiving unit and the semiconductor switching element is also shortened, the wiring resistance and heat generation by the wire can be further reduced, and the device can be used in a wider range of conditions. Furthermore, since the number of bonding locations is reduced, the reliability of the solid state relay can be further improved.

Further, by directly wire bonding the P side of the P side up semiconductor light emitting device mounted on the lead portion and the N side of the N side up semiconductor light emitting device mounted on the other lead portion, a bonding portion and a plating process are performed. The number of lead portions to be reduced is reduced, so that the manufacturing process can be simplified and the manufacturing cost can be reduced.

Further, since the lead frame is provided with an insulative lead supporting portion for supporting the lead portion on which the two semiconductor switching elements are mounted, the lead portion on which the semiconductor switching element is mounted does not bend and is parallel to the lead frame. , And disconnection of a wire between the semiconductor switching elements and a wire between the light receiving element and the semiconductor switching element can be prevented. Therefore, the yield of the solid state relay can be improved. Further, since the lead support is insulative, no electric shock is caused by the exposed lead support, no surge current flows from the lead support, and damage to the semiconductor switching element can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view showing a solid state relay according to an embodiment of the present invention.

FIG. 2 is a plan view showing a solid-state relay according to another embodiment of the present invention.

FIG. 3A is an enlarged explanatory view of a light emitting element mounting portion of the above light emitting device,
(B) is an equivalent circuit diagram of the light emitting element mounting unit.

FIG. 4A is an enlarged explanatory view of a light emitting element mounting portion of a solid state relay according to still another embodiment of the present invention,
(B) is an equivalent circuit diagram of the light emitting element mounting unit.

FIG. 5A is a plan view showing a solid state relay according to still another embodiment of the present invention, and FIG. 5B is a side sectional view showing the same.

FIGS. 6A and 6B are explanatory views showing a part of a method for manufacturing the solid state relay of the above.

FIGS. 7 (a) and 7 (b) are continuation diagrams showing a method of manufacturing the solid state relay of the above.

FIG. 8 is a side sectional structural view of a solid state relay which is still another embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the operation of a conventional solid state relay.

FIG. 10 is a plan view showing a solid state relay of the above.

FIG. 11 is an explanatory view showing a method for manufacturing the solid state relay of the above.

FIGS. 12A and 12B are explanatory diagrams showing problems in the solid state manufacturing method of the above.

FIG. 13 is a partially cutaway plan view showing a solid state relay as another conventional example.

14A is an enlarged explanatory view of a light emitting element mounting portion of the solid state relay according to the first embodiment, and FIG. 14B is an equivalent circuit diagram of the light emitting element mounting portion of the same.

[Explanation of symbols]

 5a, 5b MOSFET 3 light receiving element 3a cathode of light receiving element 6a, 6b lead for input terminal 9a, 9b, 9c die pad 11a, 11b source electrode 12 gold wire 16 lead supporting member

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tada Yui Omron Co., Ltd. (10) Hanazono Todo-cho, Ukyo-ku, Kyoto-shi, Kyoto (56) JP-A-41277 (JP, A) JP-A-5-110410 (JP, A) JP-A-4-130673 (JP, A) JP-A-6-13646 (JP, A) JP-A-63-170976 (JP, U) ) Hikaru 6-21265 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 25/00-25/18

Claims (4)

(57) [Claims] A light-emitting unit that switches between a light-emitting state and a quenched state; a light-receiving unit that receives light emitted from the light-emitting unit;
A first semiconductor switching element and a second semiconductor switching element that perform a switching operation by photovoltaic power generated in the light receiving unit; and the light receiving unit, the first semiconductor switching element, and the second semiconductor switching element In a solid state relay which is mounted on a lead frame substantially in a line and sealed and molded, an electrode of the first semiconductor switching element and an electrode of the second semiconductor switching element electrically connected to an electrode of the light receiving section. Solid state relay characterized by direct wire bonding. 2. The solid state relay according to claim 1, wherein the electrode of the light receiving section and the electrode of the first semiconductor switching element are directly wire-bonded. 3. The P-side up semiconductor light emitting device according to claim 1, wherein the light emitting unit includes at least one or more P side up semiconductor light emitting devices and at least one or more N side up semiconductor light emitting devices. 3. The solid state relay according to claim 1, wherein the N side of the N side up semiconductor element mounted on the P side and the other lead portion is directly wire-bonded. 4. An insulative lead supporting portion for supporting at least a lead portion for mounting the first semiconductor switching element and a lead portion for mounting the second semiconductor switching element on the lead frame. The solid state relay according to claim 1, 2 or 3, wherein: