JP2002157949A - Short circuit protective structure and ssr - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SSR and a short circuit protective structure capable of interrupting the overcurrent of a load short circuit without enlarging the structure and without exteriorly fitting a fuse. SOLUTION: A triac 6 is fixed to a lead frame 11, wire-bonded, and sealed with a resin in this SSR. An electric path to be interrupted by the overcurrent is formed with a bonding wire 13, and a recess 4 is formed to make a resin cover layer near the bonding wire 13 thin. When the overcurrent flows in the bonding wire 13, stress is concentrated near the boundary of the recess 4 by the thermal stress due to the expansion of the bonding wire, a crack occurs at this portion to form the escaping place of the fused bonding wire 13, and the electric path by the bonding wire 13 is cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short-circuit protection structure for interrupting a current-carrying path against an overcurrent when a load is short-circuited, and an SSR (Solid State Relay) using the same.

[0002]

2. Description of the Related Art Generally, an SSR is used to directly drive a solenoid, a motor, a heater, a lamp, or the like as a load. However, if a load short circuit occurs due to an accident or the like, the SSR itself or the SSR is caused by an overcurrent. The connected device may be damaged.

For this reason, conventionally, it is conceivable to externally attach a fuse or the like, or to incorporate a fuse in the SSR itself.

[0004]

However, the SSR
It is troublesome to externally attach a fuse to the
If a fuse is built in itself, there is a problem that the SSR becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in view of the above circumstances.
It is an object to provide a short-circuit protection structure suitable for R and this SSR.

[0006]

In order to achieve the above-mentioned object, the present invention is configured as follows.

That is, the short-circuit protection structure of the present invention is a short-circuit protection structure for an electronic component in which an element is fixed to a lead frame and is wire-bonded and sealed with a resin. The energization path is formed by a bonding wire, and the resin coating layer near the bonding wire is made thin.

Here, the vicinity of the bonding wire means
A portion near the bonding wire that receives thermal stress due to heat generated by the bonding wire when an overcurrent flows.

The term "thin" means that the thickness of the bonding wire is made thinner than other portions in the vicinity thereof so that the thermal stress tends to concentrate.

According to the present invention, when an overcurrent flows through a bonding wire due to a short circuit, as described later, before the resin around the bonding wire is carbonized, heat generated by expansion due to a rapid rise in temperature of the bonding wire. Due to the stress, the stress concentrates on the portion of the structurally weak resin coating layer near the bonding wire, and a crack is generated in this portion, or a crack is generated and a part of the resin is blown off, thereby In this case, a relief area for the melted bonding wire is formed, or a part of the melted bonding wire is blown off to cut off the current path of the bonding wire.

[0011] In another embodiment of the present invention, the portion of the thin coating layer is a concave portion.

According to the present invention, when an overcurrent flows through a bonding wire due to a short circuit, a thermal stress generated by expansion due to a rapid temperature rise of the bonding wire causes a stress near a boundary of a structurally weak recess near the bonding wire. Is concentrated, cracks occur in this part, or cracks occur and some resin is flipped off,
As a result, a relief area for the melted bonding wire is formed, or a part of the melted bonding wire is blown off to cut off the current path of the bonding wire.

An SSR according to the present invention is an SSR in which an input terminal and an output terminal are electrically insulated by an insulating circuit, and an output element for conducting between the output terminals and the SSR in which the insulating circuit is sealed with resin. A part of the current-carrying path between the element and the output terminal, which is sealed with the resin, is constituted by a conductor wire, and the resin coating layer near the conductor wire is made thin.

According to the present invention, when an overcurrent flows through a conductor wire due to a short circuit, before the resin surrounding the conductor wire is carbonized, the conductor wire is subjected to thermal stress generated by expansion due to a rapid temperature rise of the conductor wire. Stress concentrates on the portion of the structurally weak thin resin coating layer near the surface, and cracks are generated in this portion, or cracks are generated, and a portion of the resin is flipped off. Or a part of the melted conductor wire is flipped off to cut off the current path through the conductor wire.

[0015] In another embodiment of the present invention, the portion of the thin coating layer is a concave portion.

According to the present invention, when an overcurrent flows through a conductor wire due to a short circuit, thermal stress generated by expansion due to a rapid rise in temperature of the conductor wire causes stress near the boundary of a structurally weak recess near the conductor wire. Is concentrated, and cracks occur in this part, or cracks occur, and a part of the resin is flipped off, thereby forming a relief for the molten conductor wire, or forming a part of the molten conductor wire. It is flipped off to cut off the current path of the conductor wire.

In still another embodiment of the present invention,
The insulating circuit is an optical coupling element, one end of a light receiving element of the optical coupling element is connected at a first connection portion between one output terminal and one end of the output element, and The other end of the element is connected at a second connection between the other output terminal and the other end of the output element, and the conduction path is connected between the first connection and the one output terminal. And a current path between the second connection portion and the other output terminal.

According to the present invention, a short-circuit occurs in the conductor wire in the current path between the first connection portion and the one output terminal and between the second connection portion and the other output terminal. When a current flows, before the resin around the conductor wire is carbonized, the stress is concentrated on the portion of the structurally weak thin resin coating layer near the conductor wire due to the thermal stress due to the expansion of the conductor wire, Cracks occur in this part,
Alternatively, a crack is generated and a part of the resin is flipped off, thereby forming a refuge for the molten conductor wire and interrupting the current supply path by the conductor wire, so that an overcurrent flows to the output element and the light receiving element. There is no.

In another embodiment of the present invention, the insulating circuit is an optical coupling element, and one end of the light receiving element of the optical coupling element is connected to one of the output terminal and one end of the output element via a resistor. And the other end of the light receiving element is connected at a second connection between the other output terminal and the other end of the output element. A first conductor wire is connected to at least one of an energization path between one end of an element and the first connection part and an energization path between the other end of the output element and the second connection part. On the other hand, a second path is provided in at least one of an energizing path between one end of the light receiving element and the first connection portion and an energizing path between the other end of the light receiving element and the second connection portion. And the conductor wires are arranged close to each other or crossed. It is intended to be.

Here, the close arrangement or the cross arrangement is defined as
An overcurrent flows through the first conductor wire due to the short circuit, and due to thermal stress due to expansion of the first conductor wire, a stress is applied to a portion of the structurally weak thin resin coating layer near the first conductor wire. Concentrated, cracks are generated in this portion, or, when a crack is generated and some resin is flipped off, both wires are arranged close so that the second conductor wire is cut at the same time, or This means that both wires are arranged to cross each other.

According to the present invention, when an overcurrent flows through the first conductor wire due to a short circuit, before the resin surrounding the first conductor wire is carbonized, the first conductor wire is subjected to thermal stress due to expansion of the conductor wire. The stress concentrates on the portion of the structurally weak thin resin coating layer near the conductor wire of (1), and a crack is generated in this portion, or a crack is generated and a portion of the resin is repelled, thereby causing Since the conduction paths of the first conductor wire and the second conductor wire close to or intersecting with the first conductor wire are simultaneously cut off, no overcurrent flows through the output element and the light receiving element.

[0022]

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

(Embodiment 1) FIG. 1 is an external perspective view of an SSR 1 according to an embodiment of the present invention.
SR1 is, for example, a main body 1a sealed with epoxy resin.
The a, this from the bottom of the main body 1a, each pair of input terminals 2 _1, 2 ₂ and the output terminal 3 _1, 3 ₂ is extended.

[0024] The pair of input terminals 2 _1, 2 _2, not shown while being connected to the series circuit of the DC power supply and the switch, a pair of output terminals 3 _1, 3 _2, a load (not shown) and AC series circuit of a power supply Connected to the so-called,
DC input and AC output.

In this embodiment, the resin coating corresponding to the current path to be cut off inside the sealing resin is provided so that the load can be protected even if the load is short-circuited and an overcurrent flows without externally attaching a fuse or the like. In order to reduce the thickness, a circular concave portion (dent) 4 is formed. Regarding the operation of the recess 4,
It will be described later.

[0026] FIG. 2 is a circuit diagram of the SSR1, this SSR1 has an input terminal 2 _1, 2 ₂ and the output terminal 3 _1, 3 ₂ and photo-triac coupler 5 as an insulating circuit for insulating the output terminal 3 _1, 3 and triac 6 as an output element which conduction between ₂ (power element), and a snubber circuit 9 for removing noise comprising a capacitor 7 and a resistor 8, and a gate resistor 10.

In the SSR 1 of this embodiment, a fuse is not provided as in the related art,
This prevents overcurrent when a load is short-circuited and protects it without a built-in fuse.

Here, prior to the description of the short-circuit protection structure in this embodiment, if no fuse or the like is provided,
How the conventional SSR is damaged will be described.

When an overcurrent flows through the bonding wire inside the SSR due to a short circuit in the load, the bonding wire rapidly generates heat, and the temperature of the bonding wire rapidly increases as long as the phototriac coupler 5 is on. Even if the bonding wire melts, there is no place for the bonding wire to escape, so overcurrent continues to flow, and the heat generated by the bonding wire causes the surrounding resin to carbonize, and the carbonized portion becomes a bypass current path, and after the bonding wire melts In this case, the overcurrent continues to be supplied to the load, and further, the temperature rises, and finally, the resin is decomposed to generate decomposed gas.

Therefore, in this embodiment, when an overcurrent flows through the bonding wire inside the SSR due to a short circuit of the load and heats the bonding wire, the bonding wire is not heated before the resin around the bonding wire is carbonized. The stress is concentrated on the portion of the structurally weak thin resin coating layer near the bonding wire due to the thermal stress caused by the expansion of the bonding wire, and as a result, cracks or cracks occur in this portion. The resin in the portion is flipped off, thereby forming a relief for the melted bonding wire, or a portion of the melted bonding wire is flipped off, thereby interrupting the current path through the bonding wire.

FIG. 3 shows the arrangement of the copper lead frame 11, the triac 6, and the gate resistor 10 inside the SSR 1 and the wiring state thereof, and corresponds to a part of FIG. The gate terminal is wired by a gate wire 12, and one T1 terminal of the triac 6 is wired by a T1 wire 13. This T1 wire 13 is a current supply path for a load. When a current flows, the current path is cut off as follows.

That is, as shown in FIG.
As described above, the circular concave portion 4 is formed so that the resin coating layer on the upper part of the T1 wire 13 is thinner than other portions.

As described above, since the resin coating layer in the vicinity of the T1 wire 13 which is the current path to be cut off by the overcurrent is made thinner than the other portions, the overcurrent flows due to the short circuit of the load and the T1 wire 13 When heat is generated rapidly and thermal stress is generated due to expansion, stress is concentrated on the boundary portion of the structurally weak thin recess 4 to cause cracks, or
As shown in FIG. 4 (b), at the same time as the crack is generated, a part of the resin is flipped off, and at this time, a relief area of the already melted T1 wire 13 is formed, or a part of the melted T1 wire 13 is formed. Will be skipped,
Before the resin around the T1 wire 13 is carbonized, the conduction path of the T1 wire 13 is cut off. In addition,
The thermal stress due to the T1 wire 13 includes both thermal stress due to thermal expansion in a solid state before the wire 13 is melted and thermal stress due to volume expansion after the wire 13 is melted.

FIG. 5 is a partially enlarged cross-sectional view for explaining the state of the fusing of the T1 wire 13 described above. An overcurrent flows due to a short circuit in the load, and the T1 wire 13 generates heat and heat due to expansion. When the stress is generated, the thermal stress concentrates on the structurally weak thin recess 4, and a crack 15 is generated from the T1 wire 13 toward the wavefront (boundary surface) of the recess 4 as shown in FIG. Simultaneously with the occurrence of cracks, a part of the resin 16 is flipped off, forming a relief for the melted T1 wire 13, and the melted T1 wire 13 flows into the crack 15 as shown in FIG. Alternatively, the T1 wire 13 is blown off to cut off the current path before a part of the melted T1 wire 13 is flipped off to form a resin carbonized path.

In this embodiment, when the load is short-circuited,
For example, an overcurrent flows as shown by an arrow A in FIG. 2, but the T1 wire 13 is blown as shown in FIG. The route is blocked.

As a result, it is possible to protect against an overcurrent caused by a load short circuit without externally attaching a fuse or incorporating a fuse as in the related art.

(Embodiment 2) In the above embodiment,
After the T1 wire 13 wired to the triac 6 is cut off due to the overcurrent, while the phototriac coupler 5 is on, as shown by the arrow B in FIG. 8, the phototriac coupler 5 and the gate resistor 10 are connected. Since the current flows, the overcurrent cutoff is not completely performed.

When the voltage of the AC power supply connected to the output terminals 3 ₁ and 3 ₂ is low, for example, 100 V, the gate resistance 10 can withstand high temperatures, so that the resin does not carbonize and the resin Decomposition does not generate decomposition gas, but when the voltage of the AC power supply is high, for example, 200 V, the wattage consumed by the gate resistor 10 is quadrupled and the temperature of the gate resistor 10 is reduced. Rises sharply, the resin around the gate resistor 10 is carbonized, and the carbonized portion becomes a bypass current path. The temperature further rises, and the resin is finally decomposed to generate decomposed gas. .

Although it is conceivable to use a gate resistor having a large wattage, there are drawbacks in that the electrical characteristics change and the mounting area increases.

Therefore, in this embodiment, as shown in FIG. 9, an additional wire 17 is provided between one end of the gate resistor 10 and the gate terminal of the triac 6. This additional wire 17 is the same bonding wire as the gate wire 12 and the T1 wire 13.

In this embodiment, FIGS. 10 and 11
As shown in FIG.
7 are wired so as to intersect. These wires 13,
The concave portion 4 is formed above the resin layer 17 and the resin coating is made thinner as in the above-described embodiment.

In this embodiment, the first embodiment is used.
Similarly, when an overcurrent flows through the T1 wire 13 due to a short circuit in the load, a crack occurs in the resin near the T1 wire 13 or a portion of the resin at the same time as the crack is generated flies. , The additional wire 17 above the T1 wire 13 is simultaneously cut as shown in FIG. 11 (b). Thus, the T1 wire 13
And both the additional wires 17 are cut off at the same time, so that the current path is completely cut off.

FIG. 12 is a partially enlarged cross-sectional view for explaining the state of fusing of the T1 wire 13 and the additional wire 17.

Due to the short circuit of the load, an overcurrent flows through the T1 wire 13 to generate heat, and the expansion of the T1 wire 13 generates a thermal stress as shown by an arrow in FIG. As shown in FIG. 3C, the resin concentrates on the boundary portion of the concave portion 4 which is a structurally weak thin resin coating layer, and cracks occur in this portion, or a part of the resin is flipped off. The crack cuts the additional wire 17 as shown in FIG.
The 3 melted gold also jumps out and melts.

Instead of crossing the T1 wire 13 and the additional wire 17 as shown in FIG. 10, as another embodiment of the present invention, as shown in FIG. The two wires 13 and 17 may be arranged close to each other at a position where the additional wire 17 is cut.

FIG. 14 is a cross-sectional view showing an example of conditions such as dimensions of the short-circuit protection structure according to the present invention, and portions corresponding to FIG. 4 described above are denoted by the same reference numerals.

In the figure, the depth L1 of the recess 4 is 1.5
mm, the distance L2 from the bottom of the recess 4 to the T1 wire 13 is 0.5 to 0.6 mm, and the height L3 of the T1 wire 13 is 0.5 mm.
8 to 0.9 mm, the distance L4 from the lower surface of the lead frame 11 to the lower surface of the main body is 1.2 mm, and the copper lead frame 1
1 has a thickness of 0.25 mm, the diameter of the gold wire as the T1 wire 13 is 0.05 mmφ, and the thickness of the triac 6 is 0.1 mm.
21 mm, resin is epoxy resin.

The load side has a load voltage of AC100V.
Short-circuit current of zero cross input and load short-circuit is peak 60A
It is about 1.1 msec, and the input voltage is DC12V.

Under these conditions, the protection by fusing the T1 wire 13 was confirmed for 100 or more samples.

(Embodiment 3) FIG. 15 is a circuit diagram corresponding to FIG. 2 of another embodiment of the present invention, and corresponding portions are denoted by the same reference numerals.

In FIG. 15, one output terminal 3 ₁
Connection 18 between the terminal and the T1 terminal of the triac 6
In one end of the light receiving element 5a of the photo-triac coupler 5 is connected through a gate resistor 10, and in the second connecting portion 19 between the T2 terminal of the other output terminal 3 ₂ and the triac 6 The other end of the light receiving element 5a of the phototriac coupler 5 is connected.

In this embodiment, the above-described T1 wire 1
Instead of being fused at 3 parts, of the current path between the output terminal 3 and _second current paths and the second connecting portion 19 and the other between the first connection portion 18 and one of the output terminals 3 ₁ At least a portion is formed of a bonding wire, and the resin coating layer is made thin so that the overcurrent can flow through the bonding wire as described above. According to this embodiment, only one bonding wire is blown by an overcurrent, so that the energization path can be completely cut off as in the second embodiment.

(Other Embodiments) The position of the wire to be blown is not limited to the above-described first and second embodiments.

Further, a plurality of types of fusing characteristics may be provided by changing the number, diameter, and material of the wires.

For example, as shown in FIG. 16, a plurality of conductor wires 25 and 26 may be provided in series. Further, conductor wires may be provided in parallel.

In the above embodiment, the present invention is applied to the SSR of the DC input / AC output, but may be applied to the SSR of the AC input / AC output and the DC input / DC output.

The present invention is not limited to the SSR, but can be applied to other electronic components in which a chip is fixed to a lead frame, and wire bonding is performed to seal the resin.

For example, as shown in FIGS. 17A and 17B, a conductive wire 28 which is a heat generating portion of the semiconductor component 27 is used.
In addition, a circular depression 30 is provided in the package above the semiconductor element 29, and thermal stress from the conductive wire 28 generated by an overcurrent at the time of short-circuit is concentrated on the wavefront of the depression 30, as shown in FIG. In this case, the resin in the recess 30 may pop off or crack. As a result, the melted conductive wire is blown, and the semiconductor component itself and the devices, devices, and elements connected thereto can be protected from the danger of damage due to an ON failure when a short circuit occurs.

The bonding wire is not limited to gold, but may be Al or another metal.

[0060]

As described above, according to the present invention, when an overcurrent flows through a wire due to a short circuit, before the resin around the wire is carbonized, thermal stress generated by expansion due to temperature rise of the wire causes Stress concentrates on the part of the coating layer of the structurally weak thin resin near the wire, and cracks are generated in this part, or cracks are generated and some resin is flipped off, thereby causing the molten wire In this case, the escape route is formed, or the molten wire is flipped off to cut off the current path of the wire and is protected. Therefore, there is no need to externally attach a fuse or to incorporate a fuse.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of an SSR according to one embodiment of the present invention.

FIG. 2 is a circuit diagram of FIG.

FIG. 3 is a diagram showing an arrangement state inside the SSR of FIG. 1;

FIG. 4 is a diagram showing an internal change of an SSR when a load is short-circuited.

FIG. 5 is a diagram for explaining fusing of a wire.

FIG. 6 is a view corresponding to FIG. 3 in a state where the T1 wire is blown.

FIG. 7 is a circuit diagram showing a state in which the T1 wire is blown.

FIG. 8 is a diagram illustrating a current path after a T1 wire is blown.

FIG. 9 is a circuit diagram of another embodiment of the present invention.

FIG. 10 is a diagram corresponding to FIG. 3 of another embodiment of the present invention.

FIG. 11 is a diagram corresponding to FIG. 4 corresponding to another embodiment of the present invention.

FIG. 12 is a view for explaining fusing and cutting of a wire.

FIG. 13 is a diagram corresponding to FIG. 3 of still another embodiment of the present invention.

FIG. 14 is a sectional view showing an example of conditions such as dimensions.

FIG. 15 is a circuit diagram of still another embodiment of the present invention.

FIG. 16 is a circuit diagram of still another embodiment of the present invention.

FIG. 17 is a view showing still another embodiment of the present invention.

[Explanation of symbols]

1 SSR 2 _1, 2 ₂ input terminals 3 _1, 3 ₂ output terminal 4 recess 5 photo-triac coupler 6 triac 10 gate resistor 11 lead frame 12 gate wire 13 T1 wire 15 crack 17 additional wire

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shuichi Sugimoto 801 Shidokoji Shimogyo-ku, Shimogyo-ku, Higashi-iri, Minami-Fudo-cho, OMRON Corporation 5G502 BB03 EE04

Claims (6)

[Claims] 1. A short-circuit protection structure for an electronic component in which an element is fixed to a lead frame and is wire-bonded and sealed with a resin, wherein a conduction path to be cut off by an overcurrent is formed by a bonding wire. A short-circuit protection structure, wherein the resin coating layer near the bonding wire is made thin. 2. The short-circuit protection structure according to claim 1, wherein a portion of the thin coating layer is a concave portion. 3. An SSR in which an input terminal and an output terminal are electrically insulated by an insulating circuit, and an output element for conducting between the output terminals and the SSR in which the insulating circuit is sealed with resin. An SSR, characterized in that a part of a current-carrying path between the terminal and the resin is formed by a conductor wire, and the resin coating layer near the conductor wire is made thin. 4. The SSR according to claim 1, wherein the portion of the thin coating layer is a concave portion. 5. The insulated circuit is an optical coupling element, and one end of a light receiving element of the optical coupling element is connected at a first connection between one of the output terminals and one end of the output element. And the other end of the light receiving element is connected at a second connection portion between the other output terminal and the other end of the output element, and the energization path is connected to the first connection portion and the one end. 5. The SS according to claim 3, wherein the power supply path is between the second output terminal and the second connection part and the other output terminal. 6.
R. 6. The first connection between one of the output terminals and one end of the output element via a resistor, wherein the one end of the light receiving element of the optical coupling element is connected via the resistor. And the other end of the light receiving element is connected at a second connection portion between the other output terminal and the other end of the output element, and one end of the output element and the first A first conductor wire is provided on at least one of an energization path between the connection section and an energization path between the other end of the output element and the second connection section, and one end of the light receiving element. A second conductor wire is provided in at least one of an energization path between the first connection section and the first connection section and an energization path between the other end of the light receiving element and the second connection section; 5. The conductor wire according to claim 3, wherein the conductor wires are arranged close to each other or cross each other. SR.