JP2005259876A - Optical coupler and electronic apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical coupler in which even in a severe cold use environment, the characteristic deterioration or the damage of an element coated with a stress mitigating resin does not occur. <P>SOLUTION: An input signal is applied to a light emitting element 11 which emits light, the light of the light emitting element 11 is received by a light receiving element 12 to be photoelectrically transferred, and an output signal is outputted from the light receiving element 12. Further, a current is made to flow in a heat generating element 16 which generates heat which is transmitted to a silicon resin 18 through a lead frame 13a, to heat the silicon resin 18. Thus, the temperature of the silicon resin 18 can be adjusted to be higher than the temperature of the use environment, to preclude the curing or the contraction of the silicon resin 18, and large stress is not applied to the light emitting element 11 coated with the silicon resin 18, thereby not causing the characteristic deterioration or the damage of the light emitting element 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical coupling device including a light emitting element and a light receiving element, and an electronic apparatus using the same.

  As is well known, this type of optical coupling device includes a light emitting element and a light receiving element, converts an electrical signal into an optical signal by the light emitting element, and transmits and receives this optical signal from the light emitting element to the light receiving element. The optical signal is converted into an electric signal by the light receiving element, thereby transmitting the signal in a state where the input side and the output side are electrically insulated. Many of such optical coupling devices are of a double mold type sealed with a light-transmitting resin and a light-shielding resin for high reliability and stabilization of light conversion efficiency.

  FIG. 8 shows an example of a conventional optical coupling device. In this optical coupling device, the light-emitting element 101 and the light-receiving element 102 are mounted on the tip portion of each lead frame 103, 104 formed by processing a metal plate such as a Cu alloy or an Fe alloy via a conductive paste such as an Ag paste. (Referred to as die bond), each element 101, 102 is connected to each lead frame 103, 104 via Au wire 106, etc. (referred to as wire bond), and light emitting element 101 is precoated with silicone resin 107 (Coating) After spot welding or loading frame setting of each lead frame 103, 104, each element 101, 102 is positioned and opposed to each other. In this state, between each element 101, 102 Translucent resin 108, which becomes an optical path, is formed by primary transfer mold, and then intrusion of ambient light and light leakage The light-shielding resin 109 is formed by the secondary transfer mold to prevent further plating the surface of the light shielding resin 109, it is completed through forming the tie bar cutting and lead frames 103 and 104. Then, after carrying out the electrical property inspection and the appearance inspection of the optical coupling device, the optical coupling device is packed and shipped.

Here, the light-emitting element 101 is covered with the silicone resin 107 in order to protect the light-emitting element 101 from thermal stress and stress in the assembly process and use environment of the optical coupling device (see Patent Document 1 and the like).
JP-A-5-259502

  However, even if the light-emitting element 101 is covered with the silicone resin 107, when the optical coupling device is used in an extremely severe cold environment, the silicone resin 107 is cured and contracted, and a large stress is applied to the light-emitting element 101. As a result, the characteristics of the light-emitting element 101 were deteriorated or damaged. For example, when an elastomer type resin was used as the silicone resin 107, the silicone resin 107 was cured and contracted at about −40 ° C., and a large stress was applied to the light emitting element 101.

  Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and is a light that does not cause deterioration or damage of characteristics of an element covered with a resin for stress relaxation even in an extremely cold usage environment. It is an object of the present invention to provide a coupling device and an electronic device using the same.

  In order to solve the above problems, the present invention includes a light emitting element that emits light by inputting an input signal, and a light receiving element that receives light from the light emitting element and outputs an output signal. An optical coupling device in which one side is coated with a stress relaxation resin is provided with temperature adjusting means for heating the stress relaxation resin.

  In the present invention, the temperature adjusting means is a heating element that generates heat when an electric current is applied.

  Furthermore, in the present invention, the heat generating element has a resistance value lower than the reverse resistance value of the light emitting element.

  In the present invention, the light emitting element is mounted on one surface of the lead frame, the temperature adjusting means is mounted on the other surface of the lead frame, and the light emitting element and the temperature adjusting means are overlapped via the lead frame. Yes.

  Furthermore, in the present invention, the light emitting element and the temperature adjustment are mounted close to one surface of the lead frame.

  In the present invention, the stress relaxation resin contains an insulating heat conductive material.

  On the other hand, the electronic device of the present invention uses the optical coupling device of the present invention.

  According to the optical coupling device of the present invention, since the temperature adjusting means for heating the resin for stress relaxation is provided, even in an extremely cold usage environment, the resin for stress relaxation can be heated by heating the resin for stress relaxation. The temperature can be adjusted higher than the curing temperature of the resin. For this reason, the resin is not cured or contracted, and a large stress is not applied to the element covered with the resin, so that characteristic deterioration and breakage of the element can be prevented.

  For example, the temperature adjusting means is a heating element that generates heat when an electric current is applied. In the case of a circuit configuration in which the current flowing through the heat generating element may flow through the light emitting element, the resistance value of the heat generating element is set lower than the reverse resistance value of the light emitting element. As a result, it is easy for current to flow through the heating element, and reverse current does not easily flow through the light emitting element, so that destruction of the light emitting element due to the reverse current can be prevented.

  Further, the light emitting element is mounted on one surface of the lead frame, the temperature adjusting means is mounted on the other surface of the lead frame, and the light emitting element and the temperature adjusting means are overlapped via the lead frame. The heat of the means can be satisfactorily transmitted to the stress relaxation resin of the light emitting element through the lead frame.

  Furthermore, since the light emitting element and the temperature adjusting means are mounted close to one surface of the lead frame, the thickness of the optical coupling device is compared with a configuration in which the light emitting element and the temperature adjusting means are overlapped via the lead frame. Can be made thinner.

  In addition, since a resin containing an insulating heat conductive material is used as the stress relaxation resin, the thermal conductivity of the stress relaxation resin itself is improved, and the stress relaxation resin by the temperature adjusting means is improved. Temperature adjustment becomes easy.

  On the other hand, an electronic apparatus according to the present invention includes the optical coupling device according to the present invention.

  That is, the present invention is not limited to the optical coupling device, but includes an electronic apparatus to which the optical coupling device is applied. This electronic device is a power source, a vehicle control device, a factory automation (FA), a programmable controller (PLC), a communication device, etc., as long as it includes a circuit that insulates input and output and transmits signals. It does not matter if it is of a kind.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing a first embodiment of the optical coupling device of the present invention as seen from the side. In the optical coupling device of this embodiment, the lead frames 13 and 14 are prepared in advance by bending a metal plate such as a Cu alloy or an Fe alloy. Then, an insulating layer 15 made of polyimide or the like is formed on a part of the surface of one lead frame 13, and a heating element (resistive element) 16 is mounted on the insulating layer 15, and lead-free solder or conductive paste or the like. Then, both ends of the heat generating element 16 are connected to the lead frame 13.

  Further, the light emitting element 11 is mounted on the back surface of the tip portion of the lead frame 13 via a conductive paste such as Ag paste (referred to as die bonding), and the light emitting element 11 is connected to the lead frame 13 via the Au wire 17 or the like. Connect (referred to as wire bond). Similarly, the light receiving element 12 is mounted on the surface of the tip portion of the lead frame 14 via a conductive paste, and the light receiving element 12 is connected to the lead frame 14 via an Au wire 17 or the like.

  Then, the light emitting element 11 on the back surface of the lead frame 13 is pre-coated (coated) with a silicone resin 18.

  Next, the lead frames 13 and 14 are spot-welded or a loading frame set, and the elements 11 and 12 are positioned and arranged to face each other in a first mold (not shown). A translucent resin 19 serving as an optical path between the elements 11 and 12 is formed by primary transfer molding. Excess burrs of the translucent resin 19 generated by this molding are removed by a deburring die or the like.

  Subsequently, the translucent resin 19 is positioned in a second mold (not shown), and in this state, a light-shielding resin 20 is formed by a secondary transfer mold for preventing intrusion of disturbance light and light leakage. Excess burrs of the light-shielding resin 20 generated by this molding are also removed by a deburring die or the like.

  Thereafter, the surface of the light shielding resin 20 is plated. In addition, tie bar cutting is performed to cut out lead portions connecting the lead frames. This lead portion fills the gaps between the lead frames that cannot be sealed by the mold when molding the translucent resin 19 and the light-shielding resin 20, and prevents the resin leakage from the gaps between the lead frames. It will be fulfilled and will be unnecessary after the molding. Further, the optical coupling device is completed through the forming of the lead frames 13 and 14. Then, after carrying out the electrical property inspection and the appearance inspection of the optical coupling device, the optical coupling device is packed and shipped.

  FIG. 2 is an enlarged view showing the light emitting element 11, the lead frame 13, the heating element 16, and the like when viewed from the front. In FIG. 2, three lead frames 13 are shown, and the code of the central lead frame is 13a, the code of the left lead frame is 13b, and the code of the right lead frame is 13c.

  The light emitting element 11 is mounted on and connected to the back surface of the central lead frame 13 a via a conductive paste, and is connected to the left lead frame 13 b via an Au wire 17. The heating element 16 is mounted on the surface of the central lead frame 13a via the insulating layer 15, and both ends thereof are connected to the left and right lead frames 13b and 13c. Therefore, one end of the light emitting element 11 and one end of the heating element 16 are commonly connected to the left lead frame 13b, the other end of the light emitting element 11 is connected to the central lead frame 13a, and the other end of the heating element 16 is the right lead. Connected to the frame 13c. Since the insulating layer 15 is interposed between the heating element 16 and the lead frame 13 a, the heating element 16 does not have the same potential as the lead frame 13 a and the light emitting element 11. The insulating layer 15 may be provided at least on the back surface portion of the lead frame 13a on which the heat generating element 16 is mounted, and may be provided in a range from the inner edge of the lead frame 13b to the inner edge of the lead frame 13c.

  FIG. 3 is a circuit diagram showing the connection of the light emitting element 11 and the heating element 16 by the lead frames 13a, 13b, and 13c. As is clear from FIG. 3, the cathode of the light emitting element 11 and one end of the heating element 16 are connected in common to the left lead frame 13b, the anode of the light emitting element 11 is connected to the central lead frame 13a, and the other end of the heating element 16 is connected. Is connected to the right lead frame 13c.

  Here, the input signal is applied to the light emitting element 11 through the lead frames 13a and 13b. As a result, the light emitting element 11 emits light, the light of the light emitting element 11 is received by the light receiving element 12 and subjected to photoelectric conversion, and an output signal is output from the light receiving element 12.

  A current flows through the heating element 16 through the lead frames 13b and 13c. Thereby, the heat generating element 16 generates heat, and the heat of the heat generating element 15 is transmitted to the silicone resin 18 through the lead frame 13a, and the silicone resin 18 is heated.

  Such heating of the silicone resin 18 is performed when the temperature of the usage environment of the optical coupling device is extremely low. Thereby, the temperature of the silicone resin 18 can be adjusted to be higher than the curing temperature of the silicone resin 18, the curing and shrinkage of the silicone resin 18 is prevented, and a large stress is applied to the light emitting element 18 covered with the silicone resin 18. Thus, deterioration of characteristics and breakage of the light emitting element 18 can be prevented.

  For example, when an elastomer type resin that cures at about −40 ° C. is used as the silicone resin 18, the temperature of the usage environment of the optical coupling device is detected by a temperature sensor or the like, and the detected temperature is around −40 ° C. When the temperature decreases to the value, a current is supplied to the heat generating element 16 to cause the heat generating element 16 to generate heat, and the temperature of the silicone resin 18 is increased. Alternatively, when the detected temperature decreases to around −40 ° C., the amount of current flowing through the heating element 16 is increased or decreased according to the detected temperature to adjust the amount of heat generated by the heating element 16, and the silicone resin 18. Is maintained at a substantially constant temperature higher than −40 ° C. Thereby, hardening and shrinkage | contraction of the silicone resin 18 can be prevented.

  Even if the connection of the light emitting element 11 and the heat generating element 16 is changed as shown in FIG. 4, the light emission of the light emitting element 11 and the heat generation of the heat generating element 16 can be performed.

  Moreover, you may change the connection of the light emitting element 11 and the heat generating element 16 as shown to Fig.5 (a), (b). However, when the current path Ir of the heat generating element 16 is set as indicated by a dotted arrow, a reverse voltage may be applied to the light emitting element 11 and the light emitting element 11 may be destroyed. For this reason, the resistance value of the heating element 16 is made lower than the reverse resistance value of the light emitting element 11. As a result, a current easily flows through the heat generating element 16 and a reverse current hardly flows through the light emitting element 11, thereby preventing the light emitting element 11 from being broken by the reverse current.

  Of course, a pair of lead frames may be assigned to the light emitting element 11 and another pair of lead frames may be assigned to the heat generating element 16 so that the light emitting element 11 and the heat generating element 16 are completely connected.

  FIG. 6 is an enlarged view showing the light emitting element 11, the lead frame 13, the heating element 16 and the like in the second embodiment of the optical coupling device of the present invention as seen from the front. In FIG. 6, the same reference numerals are given to portions that perform the same operations as in FIG. 2, and the description will be simplified.

In this embodiment, a heat conductive material 21 having insulating properties and good heat conductivity is mixed in the silicone resin 18 covering the light emitting element 11. The heat conducting material 21 is a granular material made of C, Al, Si, Al ₂ O ₃ , ZrO ₂ or the like having a specific gravity heavier than that of the silicone resin 18, for example.

  When the heat conductive material 21 is mixed in the silicone resin 18 in this way, the heat conductivity of the silicone resin 18 itself is improved, so that the heat of the heat generating element 16 is transferred from the lead frame 13a to the silicone resin 18 in a good manner. The temperature of the entire silicone resin 18 rises quickly.

  FIG. 7 is an enlarged view showing the light emitting element 11, the lead frame 13, the heating element 16 and the like in the third embodiment of the optical coupling device of the present invention when viewed from the front. In FIG. 7, the same reference numerals are given to portions that perform the same operation as in FIG. 2, and the description will be simplified.

  In the present embodiment, the light emitting element 11 is mounted and connected to the back surface of the central lead frame 13 a via a conductive paste, and is connected to the left lead frame 13 b via an Au wire 17. Further, both ends of the heating element 16 are connected to the back surface of the central lead frame 13a and the back surface of the right lead frame 13c. Accordingly, one end of the light emitting element 11 is connected to the left lead frame 13b, the other end of the light emitting element 11 and one end of the heating element 16 are commonly connected to the central lead frame 13a, and the other end of the heating element 16 is connected to the right lead. Connected to the frame 13c.

  Even in such a configuration, the connection of the light emitting element 11 and the heating element 16 by the lead frames 13a, 13b, and 13c can be set to any of FIGS. 3, 4, 5A, and 5B.

  When the light emitting element 11 and the heat generating element 16 are provided on the back surface of the lead frame 13 as described above, the light emitting element 11 and the heat generating element 16 do not overlap as shown in FIG. Can be thinned. For this reason, the thickness of the optical coupling device can also be reduced.

  The present invention is not limited to the above embodiments, and can be variously modified. For example, the arrangement position, number, type, and the like of the heating elements may be changed.

  Further, the present invention includes not only an optical coupling device but also an electronic device including the optical coupling device. This electronic device is a power source, a vehicle control device, a factory automation (FA), a programmable controller (PLC), a communication device, etc., as long as it includes a circuit that insulates input and output and transmits signals. It does not matter if it is of a kind.

It is sectional drawing which shows Example 1 of the optical coupling device of this invention seeing from a side. FIG. 2 is an enlarged view showing a light emitting element, a lead frame, a heating element, and the like in the optical coupling device of FIG. 1 as viewed from the front. It is a circuit diagram which shows the connection of the light emitting element and light receiving element by each lead frame in the optical coupling device of FIG. It is a circuit diagram which shows the modification of the connection of the light emitting element and light receiving element by each lead frame. (A) And (b) is a circuit diagram which shows each other modification of the connection of the light emitting element and light receiving element by each lead frame. It is an enlarged view which shows the light emitting element in the Example 2 of the optical coupling device of this invention, a lead frame, a heat generating element, etc. seeing from the front. It is an enlarged view which shows the light emitting element in Example 3 of the optical coupling device of this invention, a lead frame, a heat generating element, etc. seeing from the front. It is sectional drawing which shows the conventional optical coupling device seeing from the side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light emitting element 12 Light receiving element 13, 14 Lead frame 15 Insulating layer 16 Heating element 17 Au wire 18 Silicone resin 19 Translucent resin 20 Light-shielding resin 21 Thermal conductive material

Claims (7)

An optical coupling comprising: a light emitting element that emits light upon receiving an input signal; and a light receiving element that receives light from the light emitting element and outputs an output signal, wherein at least one of the light emitting element and the light receiving element is coated with a stress relaxation resin. In the device
An optical coupling device comprising temperature adjusting means for heating a resin for stress relaxation.   2. The optical coupling device according to claim 1, wherein the temperature adjusting means is a heat generating element that generates heat when an electric current is applied.   The optical coupling device according to claim 2, wherein the heat generating element has a resistance value lower than a reverse resistance value of the light emitting element.   The light emitting element is mounted on one surface of the lead frame, the temperature adjusting means is mounted on the other surface of the lead frame, and the light emitting element and the temperature adjusting means are overlapped via the lead frame. 2. The optical coupling device according to 1.   2. The optical coupling device according to claim 1, wherein the light emitting element and the temperature adjusting means are mounted close to one surface of the lead frame.   The optical coupling device according to claim 1, wherein the stress relaxation resin includes an insulating heat conductive material.   An electronic apparatus using the optical coupling device according to claim 1.

Images