CN100454588C - Optics Housing Construction - Google Patents

Abstract

Mount the LED (6) on the mounting portion (5) of the lead frame with its light-emitting portion facing the aperture (5a). The wires (9) for connecting the LED (6) to the lead part (3) of the lead frame are located on the side where the LED (6) is mounted. The light-transmitting resin (8) transmits the light emitted by the LED (6), and is located on the side opposite to the side where the LED (6) is mounted on the lead frame. A low stress resin (2) for sealing the LED (6) and wires (9) is located on the side of the lead frame where the LED (6) is mounted. The anti-crack structure is composed of a bent part (31), a low-stress resin part (21) and an end part (81) of the light-transmitting resin in contact with the low-stress resin part (21), and the bent part (31) is located at the lead wire At the portion (3) and bent towards the side where the LED (6) is mounted, the low stress resin portion (21) is located on the side opposite to the side where the LED (6) is mounted relative to the bent portion (31).

Description

Optics Housing Construction

technical field

The present invention relates to optical device housing structures used in relatively harsh temperature environments such as optical communications, lighting, and automobiles.

Background technique

Conventionally, there has been an optical device housing structure in which an optical device such as a CCD (Charge Coupled Device) is mounted on a device mounting portion of a lead frame, the optical device and the lead portion of the lead frame are connected by wires, and are sealed with a light-transmitting resin. Encapsulation of optics, wires and lead frame (see JP2000-173947A). The light-transmitting resin is formed approximately in the shape of a rectangular parallelepiped, the material of which has satisfactory transmission characteristics with respect to light incident on the optical device. A lens is integrally formed with the upper surface of the light-transmitting resin so that light is incident on the optical device through the lens. In addition, lead portions of the lead frame protrude from the side of the light-transmitting resin, and the optical device housing is connected to prescribed electrodes through the lead portions.

However, in the conventional optical device housing structure, in order to obtain the light-transmitting properties of the light-transmitting resin, any filler is not mixed with the light-transmitting resin in order to reduce the linear expansion coefficient. Therefore, the linear expansion coefficient of the light-transmitting resin is several times that of the respective materials of the optical device and the wire. As a result, there is a problem that when the optical device housing structure is used in a severe temperature environment (for example, the temperature varies in the range of -40 degrees Celsius to 105 degrees Celsius), the wires may be broken due to thermal stress in the light-transmitting resin and damage to optics. Another problem is that light-transmitting resins can crack.

The object of the present invention is to prevent breakage of wires and destruction of optical devices, and to prevent cracking of light-transmitting resin associated with the housing structure of optical devices.

Contents of the invention

An optics housing structure according to an aspect of the present invention includes:

optical instrument;

a lead frame having a mounting portion on which an optical device is mounted and a lead portion electrically connected to the optical device;

a wire located on the side of the lead frame on which the optical device is mounted and electrically connected to the optical device by the lead portion;

a light-transmitting first resin, through which the light incident on the optical device or the light emitted from the optical device passes;

A second resin, at least part of which is located on the side of the lead frame on which the optical device is mounted, seals the optical device and the wires and has a lower coefficient of linear expansion than the first resin.

According to this structure, in the optical device housing structure, the second resin for sealing the optical device and the wiring has a lower linear expansion coefficient than the first resin. Therefore, even if the structure is used in an environment where temperature changes are relatively large, thermal stress applied to optical devices and wires can be effectively reduced. Therefore, the problem of the optical device being destroyed and the problem of the breakage of the wire can be effectively prevented.

In various embodiments, the optical device housing structure further includes an anti-crack structure for preventing the first resin from cracking. In this case, the crack prevention structure makes it difficult for cracks to occur in the first resin regardless of whether the linear expansion coefficient of the first resin is larger than that of the lead frame or the like. Therefore, even if the structure is used in an environment where temperature changes are relatively large, it is possible to effectively prevent the problem of cracks occurring in the first resin.

In one embodiment of the optics housing structure, the shatter resistant structure comprises:

a bent portion, which is located at the lead portion of the lead frame and is bent toward the side on which the optical device is mounted;

a portion of the second resin on the side opposite to the side on which the optical device is mounted with respect to the curved portion; and

The end portion of the first resin that is in contact with the portion of the second resin.

According to the present embodiment, in the crack prevention structure, the bent portion is located at the lead portion of the lead frame and is bent toward the side where the optical device is mounted. A portion of the second resin is located on the side opposite to the side where the optical device is mounted with respect to the bent portion. An end portion of the first resin is in contact with a portion of the second resin. With this arrangement, the shear stress generated in the end portion of the first resin can be effectively reduced. As a result, even if the structure is used in an environment where temperature changes are relatively large, the problem of cracking in the first resin can be effectively prevented.

In one embodiment of the optics housing structure, the shatter resistant structure comprises:

a recessed portion located at the lead portion of the lead frame and having a cavity on the side opposite to the side on which the optical device is mounted;

a portion of the second resin that is located within the recessed portion; and

The end portion of the first resin that is in contact with the portion of the second resin.

According to the present embodiment, in the crack prevention structure, the recessed portion is located at the lead portion of the lead frame and has a cavity located on the side opposite to the side where the optical device is mounted. A portion of the second resin is located inside the recessed portion. An end of the first resin is in contact with a portion of the second resin. With this arrangement, the shear stress generated in the end portion of the first resin can be effectively reduced. As a result, even if the structure is used in an environment where temperature changes are relatively large, the problem of cracking in the first resin can be effectively prevented.

In one embodiment of the optics housing structure, the shatter resistant structure comprises:

a bent portion positioned at the lead portion of the lead frame and bent toward the side on which the optical device is mounted; and

The end portion of the first resin, the end surface of which is aligned with the edge of the curved portion.

According to the present embodiment, in the crack prevention structure, the bent portion is located at the lead portion of the lead frame and is bent toward the side where the optical device is mounted. An end portion of the first resin having an end surface is aligned with an edge of the bent portion. With this arrangement, the shear stress generated in the end portion of the first resin can be effectively reduced. As a result, even if the structure is used in an environment where temperature changes are relatively large, the problem of cracking in the first resin can be effectively prevented.

In one embodiment of the optical device housing structure, an end surface of the end portion of the first resin is substantially flush with a surface of a curved portion on a side opposite to a side on which the optical device is mounted.

According to the present embodiment, by making the end surface of the end portion of the first resin substantially flush with the surface of the bent portion at the lead portion of the lead frame, the shear resistance generated in the end portion of the first resin can be reduced. stress. Therefore, the problem of cracks occurring in the first resin can be effectively prevented.

In one embodiment of the optics housing structure, the second resin is formed by transfer molding.

According to the present embodiment, the second resin is formed by transfer molding. Therefore, residual stress generated in the optical device and the wires sealed with the second resin can be effectively reduced.

In one embodiment of the optics housing structure, the second resin does not contain any mold release agent.

According to the present embodiment, the second resin does not contain any release agent, and thus, the adhesion between the second resin and the first resin can be improved.

In one embodiment of the optical device housing structure, the first resin contains a filler for reducing the coefficient of linear expansion of the first resin.

According to the present embodiment, the coefficient of linear expansion of the first resin is reduced by the filler, and therefore, the difference in coefficient of linear expansion between the second resin and the lead frame can be reduced. Therefore, excessive thermal stress can be prevented from being generated in the first resin, and generation of cracks can be effectively prevented.

Note that the amount of the filler mixed into the first resin should preferably be such that the light transmittance of the first resin is not greatly reduced.

In one embodiment of the optical device housing structure, the anti-crack structure includes a first resin having a lens portion that collects light incident on or emitted from the optical device and a base portion , the base portion is connected to the lens portion, and the base portion has a thickness not greater than 0.5 mm.

According to the present embodiment, the stress concentrated to the base portion of the first resin is reduced. Therefore, generation of cracks in the first resin can be effectively prevented.

In one embodiment of the optical device housing structure, the anti-crack structure includes a first resin having a lens portion that collects light incident on or emitted from the optical device and a base portion, the lens portion collecting light incident on or emitted from the optical device, the The base portion is connected to the lens portion, and the first resin has an area smaller than that of the mounting portion of the lead frame when viewed from an emission or incidence direction of light. According to the present embodiment, the stress concentrated to the base portion of the first resin is reduced. Therefore, generation of cracks in the first resin can be effectively prevented.

In one embodiment of the optical device housing structure, the anti-crack structure includes a first resin having a lens portion that collects light incident on or emitted from the optical device and a base portion, the lens portion collecting light incident on or emitted from the optical device, the The base portion is connected with the lens portion, and the first resin has an area smaller than that of the mounting portion of the lead frame when viewed from an emission or incident direction of light, and the base portion has a thickness smaller than that of the lens portion .

According to the present embodiment, the stress concentrated to the base portion of the first resin is reduced. Therefore, generation of cracks in the first resin can be effectively prevented.

In one embodiment of the optical device housing structure, the second resin has a part located on the side opposite to the side of the lead frame on which the optical device is mounted, and the part of the second resin is located at least at a portion other than the part where the first resin is placed. part of a part other than the lead frame.

According to the present embodiment, the parts of the second resin are placed on the same side as the lead frame on which the first resin is mounted. Therefore, for example, by using the part of the second resin as a reference, the device can be mounted on other equipment or the like. Therefore, an optical device housing structure capable of aligning positions based on the external shape can be obtained.

In one embodiment of the optical device housing structure, the anti-crack structure includes a first resin having a lens portion that collects light incident on or emitted from the optical device and a base portion, The base portion is connected to the lens portion and bonded to at least the lead frame with an adhesive material.

According to the present embodiment, the first resin is formed separately from the lead frame without using, for example, insert molding, and the first resin is bonded to the lead frame with an adhesive material. Therefore, generation of stress due to molding shrinkage when the first resin is formed by, for example, insert molding can be prevented. As a result, generation of cracks in the first resin can be effectively prevented.

In one embodiment of the optics housing structure, the adhesive material comprises a resin having a glass transition point lower than the lowest storage temperature.

According to this embodiment, the adhesive material comprises a resin whose glass transition point is lower than the lowest storage temperature, therefore, the elasticity of the adhesive material is relatively large in the normal use environment of the optical device housing structure. Therefore, since the shear stress generated between the first resin and the lead frame can be reduced, cracks generated in the first resin can be effectively prevented. Note that the storage temperature means the ambient temperature range in which the resin can be preserved without applying an electric load, and is described in JIS-C7021-B10.

In one embodiment of the optics housing structure, the adhesive material comprises a resin having a cure point not lower than the lowest storage temperature and not higher than the highest storage temperature.

According to this embodiment, the adhesive material comprises a resin whose curing point is not lower than the lowest storage temperature and not higher than the highest storage temperature. Therefore, during the curing process of the adhesive material, the thermal stress caused by curing can be relatively reduced. Therefore, since the shear stress generated in the first resin can be reduced, it is also possible to effectively prevent cracks from being generated in the first resin.

In one embodiment of the optics housing structure, the ripstop structure includes a first resin, and

The first resin has a plurality of lens parts and a plurality of base parts, the lens parts collect light incident on the optical device or light emitted from the optical device, the base parts extend to the respective lens parts, and the plurality of lens parts and the base parts are combined separated from each other.

According to the present embodiment, a plurality of combined lens portions and base portions are separated from each other, and therefore, stress concentrated to the base portion of the first resin can be reduced. Therefore, generation of cracks in the first resin can be effectively prevented.

As described above, in the optical device housing structure of the present invention, the first resin transmits the light incident on the optical device or the light emitted from the optical device, the first resin is located on the mounting portion side of the lead frame, and the second resin A resin seals the optical device and the wires, the second resin is located on the other side of the mounting portion, and the second resin has a lower linear expansion coefficient than the first resin. Therefore, even if the optical device housing structure is used in an environment with relatively large temperature changes, thermal stress applied to the optical device and wires can be effectively reduced. Therefore, the problem of destruction of the optical device and the problem of wire breakage can be effectively prevented.

In addition, the problem of cracks occurring in the first resin can be effectively prevented by the crack prevention structure, regardless of whether the linear expansion coefficient of the first resin is larger than that of the lead frame or the like, and even if the structure is used in an environment where temperature changes are relatively large The same is true in .

Description of drawings

1A is a cross-sectional view showing the structure of an optical device housing of a first embodiment of the present invention;

1B is a plan view showing the structure of the optical device housing of the first embodiment;

2 is a cross-sectional view showing the structure of an optical device housing of a second embodiment;

3 is a cross-sectional view showing the structure of an optical device housing of a third embodiment;

4 is a cross-sectional view showing the structure of an optical device housing of a comparative example;

5 is a cross-sectional view showing the structure of an optical device housing of a fourth embodiment;

6 is a cross-sectional view showing the structure of an optical device housing of a fifth embodiment;

7 is a cross-sectional view showing the structure of an optical device housing of a sixth embodiment;

8 is a cross-sectional view showing the structure of an optical device housing of a seventh embodiment;

9 is a cross-sectional view showing the structure of an optical device housing of a modified example of the fifth embodiment;

Detailed description

The invention will now be described by way of a number of embodiments with reference to the accompanying drawings.

[First embodiment]

FIG. 1A is a cross-sectional view showing the structure of an optical device housing of a first embodiment of the present invention. FIG. 1B is a plan view showing the structure of the optical device housing of the first embodiment.

In the optical device package structure, an LED (Light Emitting Diode) 6 as an optical device is mounted on the lower surface side of the mounting portion 5 of the lead frame in FIG. 1 . The aperture 5a through which the light emitted by the LED6 is located at the mounting portion 5 of the lead frame, and the light-emitting portion of the LED 6 is facing the aperture 5a. The LED 6 is electrically connected to the lead portion 3 of the lead frame through a wire 9 . The wire 9 is located on the side of the lead frame in the mounting section (the side where the LED 6 is mounted). LED 6 and wire 9 are sealed with low stress resin 2 containing silicon dioxide as filler. The low stress resin 2 is located on the side of the lead frame in the mounting portion 5 (the side where the LED 6 is mounted). On the other hand, the light-transmitting resin 8 is located on the side opposite to the side where the LED 6 is mounted on the lead frame in the mounting portion 5, and is made of a material having light permeability for light emitted by the LED 6. The light-transmitting resin 8 is constituted by integrally forming a lens portion 8a that condenses light emitted from the LED 6 with a base portion 8b that supports the lens portion 8a. The cross section of the base portion 8b is trapezoidal and rectangular in plan. The low-stress resin 2 is provided by a resin whose linear expansion coefficient can be reduced as a whole by adding filler silica or the like having a small linear expansion coefficient to, for example, epoxy resin. The light-transmitting resin 8 is provided by, for example, transparent epoxy resin.

Optics housing construction is shatter resistant. The anti-crack structure is composed of the bent portion 31 at the lead portion 3 of the lead frame, the low stress resin portion 21 at the side opposite to the side where the LED 6 is mounted with respect to the bent portion 31, and the low stress resin portion 21. The end portion 81 of the light-transmitting resin that is in contact with each other is formed. The bent portion 31 of the lead part 3 of the lead frame is bent toward the side where the LED 6 is installed.

In the optical device housing structure of this structure, the LED 6 and the wire 9 are sealed with the low-stress resin 2, and the linear expansion coefficient of the low-stress resin 2 has an The linear expansion coefficient of the LED 6 and the linear expansion coefficient of the lead frame and the wire are close to the value. Therefore, even if the structure is used in an environment with relatively large temperature changes, it can effectively reduce the thermal stress applied to the LED 6 and the wire 9. As a result, the problem of destroying the LED 6 and the problem of breaking the wire 9 can be effectively prevented.

Furthermore, since the optical device housing structure has a crack-resistant structure, cracking of the light-transmitting resin 8 can be effectively prevented even when the structure is used in an environment where temperature changes are relatively large. That is, the light-transmitting resin 8 is not mixed with any filler to preserve satisfactory transmission characteristics for light from the LED 6, and therefore, the light-transmitting resin 8 has a linear expansion coefficient equal to that of the lead frame and the low-stress resin 2 Several times the coefficient of linear expansion. However, since the end portion 81 of the light-transmitting resin is in contact with the low-stress resin portion 21, the shear stress generated in the end portion 81 of the light-transmitting resin becomes stronger than, for example, the end portion in contact with the lead portion of the lead frame. Small. As a result, generation of cracks in the light-transmitting resin 8 can be effectively prevented.

Furthermore, by separately forming the low-stress resin 2 and the light-transmitting resin 8 on the bottom side and the top side of the lead frame, respectively, the optical device housing structure can be easily produced. That is, the time and labor required for positioning, etc., of a lens made of glass are compared with, for example, a case where a lens made of glass and used for converging light emitted from an LED is formed by insert molding of a low-stress resin. Less, therefore, can easily generate the structure. Furthermore, since the low-stress resin 2 is located only on the side of the lead frame on which the LED 6 is mounted, the resin in the metal mold during the molding process is less likely than the conventional case where only light-transmitting resin is used to seal both sides of the lead frame. Mobility is more satisfactory. Therefore, the problem of discharge into the sealing resin can be prevented. Furthermore, the position of the gate of the metal mold for molding can be set with relatively few restrictions. Thus, optics housing structures can be produced relatively easily by co-injection molding in a cost-effective manner.

[Second Embodiment]

Fig. 2 is a sectional view showing the structure of an optical device housing of a second embodiment.

The optical device housing structure of the second embodiment is different from that of the first embodiment only in the configuration of the crack prevention structure. In the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and will not be described in detail.

The anti-crack structure possessed by the optical device housing structure of the second embodiment is formed by the recessed portion 32 located at the lead portion 3 of the lead frame, the low-stress resin portion 22 located in the recessed portion 32, and the contact with the low-stress resin portion 22. The end portion 81 of the light-transmitting resin is jointly constituted. The recessed portion 32 of the lead portion of the lead frame has a cavity at the side opposite to the side where the LED 6 is mounted.

Even when used in an environment with relatively large temperature changes, the optical device housing structure of this embodiment can effectively prevent the cracking of the light-transmitting resin 8 by virtue of the cracking prevention structure. That is, since the end portion 81 of the light-transmitting resin is in contact with the low-stress resin portion 22 in the crack prevention structure, the shear stress generated in the end portion 81 of the light-transmitting resin can be effectively reduced. Therefore, even though the resin has a coefficient of linear expansion several times that of the lead frame and the low-stress resin 2 , it is possible to effectively prevent cracks from being generated in the light-transmitting resin 8 .

[Third embodiment]

Fig. 3 is a sectional view showing the structure of an optical device housing of a third embodiment.

The optical device housing structure of the third embodiment is different from that of the first embodiment only in the configuration of the crack prevention structure. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and will not be described in detail.

The crack prevention structure possessed by the optical device housing structure of the third embodiment is constituted by the bent portion 33 located at the lead portion 3 of the lead frame and the end portion 81 of the light-transmitting resin having a connection with the bent portion 33. Edge-aligned end surfaces 83 . The bent portion 33 of the lead portion of the lead frame is bent toward the side where the LED 6 is mounted.

Even when used in an environment with relatively large temperature changes, the optical device housing structure of this embodiment can effectively prevent the cracking of the light-transmitting resin 8 by virtue of the cracking prevention structure. That is, in the case of a configuration in which the end portion 81 of the light-transmitting resin is in contact with the bent portion 33 of the lead portion and the end surface 83 at the end portion of the light-transmitting resin is aligned with the edge of the bent portion 33 in the crack prevention structure, effective The shear stress generated in the end portion 81 of the light-transmitting resin is reduced as much as possible. Therefore, even though the linear expansion coefficient of the light-transmitting resin 8 is several times that of the lead frame and the low-stress resin 2 , cracks in the light-transmitting resin 8 can be effectively prevented.

In each embodiment, the method of forming the light-transmitting resin 8 is not particularly limited. On the other hand, in order to reduce residual stress in these components, the low-stress resin 2 for sealing the LED 6, the wire 9, etc. should preferably be formed by transfer molding.

Furthermore, preferably, no release agent should be used for the low stress resin 2 . This is because if a release agent is used for low-stress resin, when the light-transmitting resin is formed after the low-stress resin is formed, the release agent sometimes seeps out from the low-stress resin and damages the low-stress resin. The adhesion between the light-transmitting resin and the light-transmitting resin is adversely affected.

In addition, it is acceptable to mix fillers such as silicon dioxide into the light-transmitting resin 8 in order to reduce the coefficient of linear expansion to such an extent that the light-transmitting characteristics (light transmittance) are not impaired. With this arrangement, the shear stress generated in the light-transmitting resin can be further reduced, and the generation of cracks in the light-transmitting resin can be more effectively prevented.

In addition, the LED 6 may be another optical device such as a CCD, VCSEL (Vertical Cavity Surface Emitting Laser), PD (Photodiode) or the like.

In addition, the shapes of the light-transmitting resin 8 and the low-stress resin 2 are not limited to the shape of a rectangular parallelepiped, but can be changed into other shapes as required.

In addition, the shape of the lead frame can be changed to another shape as needed. For example, the mounting portion 5 and the lead portion 3 may be integrally formed, and any number of lead portions 3 may be provided.

[example]

The optical device housing structures of the first to third embodiments were produced and tested in an environment with a temperature range of -40°C to 105°C. In addition, for the optical device housing structures of the first to third embodiments, simulations were performed by FEM (Finite Element Method) with a computer to calculate the shear stress generated under the test conditions. In addition, as a comparative example, an optical device housing structure without the rupturing prevention structure of the present invention was tested, and the calculation of the shear stress was performed.

FIG. 4 is a cross-sectional view showing the structure of an optical device housing of a comparative example. The optical device housing structure has some of the same components as the optical device housing structure of the first embodiment, except that the lead portion 103 of the lead frame protrudes laterally along the boundary line between the light-transmitting resin 8 and the low-stress resin 2 , and does not provide any breakage-resistant structure. In the example shown in FIG. 4, the same components as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals.

Materials used in producing the optical device housing structures of the first to third embodiments and comparative examples are as follows. That is, EME6710 produced by Sumitomo Bakelite Co., Ltd. was used for the low-stress molding resin 2 . In addition, NT600 produced by Nitto Denko Co., Ltd. was used for the light-transmitting resin 8, and copper alloy KFC produced by Kobe Steel Co., Ltd. was used for the lead frame. Then, the low-stress resin 2 is formed to a thickness of 2 mm, the light-transmitting resin 8 is formed to a thickness of 1 mm, and the lead frame is formed to a thickness of 0.25 mm. Using these component parts, a housing structure with a housing size of 6 square millimeters was produced.

Table 1 shows the physical properties of the materials making up the parts.

Table 1

Coefficient of linear expansion (ppm/k) Young's modulus (GPa) Poisson's ratio GaAs 5.9 85.5 0.55 Si 2.8 187 0.25 Au 14.2 78 0.44 Cu alloy 17 128 0.35 Luminous resin 60-70 3-3.5 0.3 low stress resin 8-18 15-30 0.25-0.3

As shown in Table 1, since the filler is mixed, the low stress resin 102 has a linear expansion coefficient that is comparable to that of copper alloys for lead frames, gold for wires, and gallium arsenide and silicon for LEDs 6 The coefficient is close to the numerical value. On the other hand, the light-transmitting resin 108 is not mixed with any filler so as to avoid the reduction of the light-transmitting characteristic (this light-transmitting characteristic is for the light emitted by the LED 6), and it has a linearity that is several times that of other structural materials. Coefficient of expansion.

The optical device housing structures of the first to third embodiments and the comparative example were made of materials having the physical properties shown in Table 1. The housing structure is produced by insert molding a low stress resin 2 into the lead frame mounted with the LED 6 followed by molding of the light transmissive resin 108 . These optic housing structures are subjected to temperature cycling tests while placed in environments with temperatures ranging from -40°C to 105°C.

As a result, cracks were generated in the light-transmitting resin 8 of the comparative example. Specifically, in FIG. 4 , cracking occurs most frequently in those portions where the end portion 81 of the light-transmitting resin is in contact with the lead portion 103 of the lead frame and the low-stress resin 8 . Second, cracking occurs more often in those portions where the end portion 81 of the light-transmitting resin is in contact with the lead portion 103 of the lead frame. The occurrence of these cracks is presumably mainly attributable to the shear stress generated in the end portion 81 of the light-transmitting resin due to the difference in coefficient of linear expansion between the components in contact with each other.

On the other hand, in the optical device housing structures of the first to third embodiments, hardly any generation of cracks was observed at the end portion 81 of the light-transmitting resin. This is presumably attributable to the fact that the low-stress resin portions 21 and 22 in contact with the end portion 81 of the light-transmitting resin have a relatively small Young's modulus, although their linear expansion coefficients are different from those of the light-transmitting resins in the first and second embodiments. Photoresin 8, therefore, generates relatively little shear stress at the boundaries between these resins. Furthermore, in the second embodiment, by forming the terminal surface 83 at the light-transmitting resin terminal portion which is aligned with the edge of the bent portion 31 of the lead portion of the lead frame, the light-transmitting resin terminal portion 81 can be reduced in size. The shear stress at .

According to the test results, by forming the lead part 3 of the lead frame, the lead part protrudes only from the second resin, instead of protruding from the light-transmitting resin as the first resin and the second resin as the second resin as in the first and second embodiments. Protruding from the boundary between the low-stress resins of the resin presumably prevents excessive shear stress from being generated in the first resin. Furthermore, by forming the lead portion 3 of the lead frame so that the edge of the bent portion is located at the boundary between the light-transmitting resin as the first resin and the low-stress resin as the second resin in the second embodiment, it is possible to roughly prevent Excessive shear stress is generated in the first resin.

Table 2 shows the calculation results of the simulation with FEM for the optical device housing structures of the first to third embodiments and the comparative example. Regarding this simulation, since the glass transition point of the light-transmitting resin 8 is 120 degrees Celsius, by changing the temperature condition between -40 degrees Celsius and 105 degrees Celsius, at the same time the total stress of the shell structure will become zero at the set 120 degrees Celsius, A simulation corresponding to the temperature cycling test is performed.

Form 2

Shear stress at position A (MPa) Shear stress at position B (MPa) Comparison example 70 51 The first embodiment 35.8 28 Second embodiment 35.8 28 The third embodiment 45.8 40

In Table 2, position A is where the light-transmitting resin 8 is in contact with the lateral edges of the lead portions 3 and 103 of the lead frame and the low-stress resin 2 at or near the light-transmitting resin end portion 81. part. The position B is a portion where the light-transmitting resin 8 is in contact with the lateral centers of the lead parts 3 and 103 of the lead frame at or near the light-transmitting resin end portion 81 .

The simulated results in Table 2 correspond satisfactorily to those obtained from the temperature cycling tests with the real thing. NT600 produced by Nitto Denko and used to manufacture the light-transmitting resin 8 has a bending strength of 130 MPa. Since the shear stress of the resin is usually one-third of its bending strength, it can be estimated that the shear strength of the light-transmitting resin 8 is about 45 MPa. It can be judged that when the value of the shear stress calculated by simulation exceeds the shear stress of the light-transmitting resin, shear fracture will easily occur. Actually, in the comparative example, the shear stress obtained by the simulation calculation greatly exceeded 45 MPa at both positions A and B, and many cracks were generated in the end portion 81 of the light-transmitting resin during the temperature cycle test. On the other hand, according to the first and second embodiments, the shear stress obtained by the simulation calculation is lower than 45 MPa at the positions A and B, and in the temperature cycle test, no any damage occurs in the end portion 81 of the light-transmitting resin. rupture. Furthermore, although the shear stress obtained by simulation calculation at position A slightly exceeded 45 MPa in the third embodiment, no cracks were generated in the end portion 81 of the light-transmitting resin by the temperature cycle test.

According to these results, the cracks generated in the light-transmitting resin 8 are presumably attributable to the generation of extremely large shear stresses at the portion where the end portion 81 of the light-transmitting resin is in contact with the lead portion 103 of the lead frame, especially It is generated at those portions which are located at both lateral ends of the lead portion 103 and which are also in contact with the low-stress resin 2 . In this case, according to the optical device housing structure of the present invention, it can effectively reduce the shear stress at the end portion 81 of the light-transmitting resin by means of the anti-crack structure, and presumably can effectively prevent the light-transmitting resin 8 from breaking. rupture.

[Fourth Embodiment]

Fig. 5 is a sectional view showing the structure of an optical device housing of a fourth embodiment.

The optical device housing structure of the fourth embodiment is different from that of the first embodiment only in the configuration of the crack prevention structure. In the fourth embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and will not be described in detail.

By setting the thickness of the base portion 8b of the light-transmitting resin 8 to a prescribed thickness, the crack prevention structure possessed by the optical device housing structure of this embodiment is provided. Note that the base portion 8 b refers to the portion for supporting the lens 8 a of the light-transmitting resin 8 . The thermal stress generated in the light-transmitting resin 8 is mainly caused by the difference in the linear expansion coefficient and Young's modulus of the lead frames 3 and 5 . In particular, the thicker the thickness of the base portion 8b of the light-transmitting resin 8, the greater the shear stress generated between the lead frames 3 and 5 and the light-transmitting resin 8, thereby easily causing Stress concentrates and cracks.

In this case, by setting the thickness of the base portion 8b of the light-transmitting resin 8 to 0.5 mm or less, the shear stress generated in the end portion 81 of the light-transmitting resin can be effectively reduced. That is, although the light-transmitting resin 8 has a linear expansion coefficient several times that of the lead frames 3 and 5 and the low-stress resin 2, by using the crack prevention structure, it is possible to effectively prevent cracks from being generated in the light-transmitting resin 8 .

From the viewpoint of crack prevention, preferably, the thickness of the base portion 8b of the light-transmitting resin 8 should be as thin as possible. However, the lower limit should preferably be set at about 0.3 mm in consideration of flowability of the resin during molding.

[Fifth Embodiment]

Fig. 6 is a sectional view showing the structure of an optical device housing of a fifth embodiment.

The optical device housing structure of the fifth embodiment is different from that of the first embodiment only in the configuration of the crack prevention structure. In the fifth embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and will not be described in detail.

By making the area of the light-transmitting resin 8 smaller than the area of the mounting portion 5 of the lead frame when viewed from the light emitting direction of the LED 6, the anti-crack structure possessed by the optical device housing structure of the present embodiment is provided. Note that the light-transmitting resin 8 is composed of the lens portion 8a and the base portion 8b supporting the lens portion 8a, and the light-transmitting resin 8 has the same area as the base portion 8b. The thermal stress generated in the light-transmitting resin 8 is mainly caused by the difference in linear expansion coefficient and Young's modulus between those of the lead frames 3 and 5 . In particular, the larger the area of the light-transmitting resin 8, the greater the shear stress generated between the resin and the lead frames 3 and 5 near the end portion of the light-transmitting resin 8, so that Stress concentration is caused at the end portion and cracks are generated.

In this case, by making the area of the light-transmitting resin 8 smaller than the area of the mounting portion 5 of the lead frame viewed from the light-emitting direction of the LED 6, the shear stress generated in the end portion 81 of the light-transmitting resin can be effectively reduced. That is, even though the light-transmitting resin 8 has a linear expansion coefficient several times that of the lead frames 3 and 5 and the low-stress resin 2 , generation of cracks in the light-transmitting resin 8 can be effectively prevented by using the crack prevention structure.

Furthermore, by reducing the thickness and area of the light-transmitting resin 8 by combining the fourth embodiment and the fifth embodiment, it is possible to more effectively prevent cracks from being generated in the light-transmitting resin 8 . In addition, as shown in FIG. 9, when the light-transmitting resin 8 is composed of a plurality of lens parts 8a, 8a... and a plurality of base parts 8b, 8b... A combined lens portion 8a and base portion 8b can more effectively prevent cracks in the light-transmitting resin 8 .

[Sixth Embodiment]

Fig. 7 is a sectional view showing the structure of an optical device housing of a sixth embodiment.

The optical device housing structure of the sixth embodiment is different from that of the first embodiment only in the configuration of the crack prevention structure. In the sixth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and will not be described in detail again.

The optical device housing structure of this embodiment has a crack prevention structure similar to that of the optical device housing structure of the fifth embodiment. That is, the light-transmitting resin 8 is made of the lens portion 8a and the base portion 8b supporting the lens portion 8a, and the area of the base portion 8b or the area of the light-transmitting resin 8 is smaller than that of the lead frame when viewed from the light emitting direction of the LED 6. Mounting area of part 5. In this case, since the light-transmitting resin 8 is formed with a necessary minimum size so as to transmit the light of the LED 6, there are cases where the housing structure cannot be aligned by using the surface of the light-transmitting resin 8.

Therefore, the part 2a of the low-stress resin is located on the surfaces of the lead frames 3 and 5 (the side where the light-transmitting resin 8 is located), and at least in a portion other than that where the light-transmitting resin 8 is located. By using the surface of the part 2a of low stress resin, the housing structure can be aligned with the equipment to which the housing structure is to be mounted. When the low-stress resin 2 is molded to the lead frames 3 and 5, it is appropriate to block the low-stress resin material by placing a pin or the like in a position serving as the portion of the light path in which the light-transmitting resin 8 is to be placed. inflow.

When the base portion 8b of the light-transmitting resin 8 is formed with a reduced thickness, the parts 2a of the low-stress resin can be formed on the surfaces of the lead frames 3 and 5 on the side where the light-transmitting resin 8 is placed. Even when alignment cannot be achieved with the base portion 8b of the light-transmitting resin 8 having a reduced thickness, alignment of the housing structure can be achieved by the surface of the member 2a of the low-stress resin.

[Seventh embodiment]

Fig. 8 is a sectional view showing the structure of an optical device housing of a seventh embodiment.

The optical device housing structure of the seventh embodiment is different from that of the sixth embodiment only in the configuration of the crack prevention structure. In the seventh embodiment, the same components as those in the sixth embodiment are denoted by the same reference numerals and will not be described in detail again.

Except that the area of the light-transmitting resin 8 is smaller than the area of the mounting portion 5 of the lead frame when viewed from the light emitting direction of the LED 6, the light-transmitting resin 8 is bonded at least to the mounting portion 5 of the lead frame with an adhesive, thereby constituting the second The anti-crack structure possessed by the housing structure of the optical device in the seventh embodiment. The light-transmitting resin 8 is composed of a lens portion 8a and a base portion 8b supporting the lens portion 8a, and at least the bottom of the base portion 8b is bonded to the mounting portion 5 of the lead frame with an adhesive material.

If the light-transmitting resin 8 is integrally composed of the lead frames 3 and 5 through insert molding, residual stress, thermal stress, etc. are generated in the light-transmitting resin 8, and the residual stress can be attributed to the stress caused by molding shrinkage, The thermal stress is attributed to the temperature difference between the temperature at the time when the curing of the light-transmitting resin starts and the ambient temperature. The residual stress becomes a cause of cracks in the light-transmitting resin 8 .

In this case, according to the present embodiment, the light-transmitting resin 8 is formed separately from the lead frames 3 and 5, and the light-transmitting resin 8 is fixed to at least the mounting portion 5 of the lead frame with the adhesive material 10. In this arrangement, only thermal stress (due to the temperature difference between the temperature at the time when the curing of the light-transmitting resin starts and the ambient temperature) becomes a cause of residual stress, and therefore, the generation of stress in the light-transmitting resin 8 can be reduced. possibility of rupture. Furthermore, by making the adhesive material 10 act as a stress buffer, it is possible to effectively prevent cracks from being generated in the light-transmitting resin 8 .

In particular, a material with a glass transition point lower than the lowest storage temperature of the optics housing should preferably be used as the adhesive material 10 . In this arrangement, the adhesive material 10 can form a rubbery state in the normal environment in which the optics housing is used. In this arrangement, the Young's modulus of the adhesive material 10 can be reduced, and therefore, the stress difference between the lead frames 3 and 5 and the light-transmitting resin 8 fixed by the adhesive material 10 can be weakened. Therefore, by effectively preventing the stress from being concentrated on the light-transmitting resin 8, the occurrence of cracks can be effectively prevented.

Furthermore, by using an adhesive material 10 whose curing point is not lower than the lowest storage temperature and not higher than the highest storage temperature of the optics housing, during the curing process of the adhesive material 10, the difference between the curing point and the surrounding area can be reduced. The temperature difference between. Therefore, thermal stress generated when the adhesive material 10 is cured can be reduced, and generation of cracks in the light-transmitting resin 8 can be effectively prevented. The curing point of the adhesive material 10 should preferably have a value which is the arithmetic mean of the values of the lowest storage temperature and the highest storage temperature of the optics housing.

In the fourth to seventh embodiments, the method of forming the light-transmitting resin 8 is not particularly limited. On the other hand, since the low-stress resin 2 seals the LED 6, wires 9, etc., transfer molding should preferably be used in order to reduce residual stress in these parts.

Also, for low stress resin 2, it is best not to use any release agent. This is because if a release agent is used for the low stress resin, when the light-transmitting resin is formed after the low-stress resin is formed, the release agent may seep out of the low-stress resin and cause damage to the low-stress resin and the transparent resin. Bonding between photoresins can be detrimental.

In addition, LED 6 can be another optical device, such as CCD, VCSEL or PD.

In addition, the shapes of the light-transmitting resin 8 and the low-stress resin 2 are not limited to the shape of a rectangular parallelepiped, but can be changed to other shapes as required.

In addition, the shape of the lead frame can also be changed to another shape as needed. For example, the mounting portion 5 and the lead portion 3 may be integrally formed, and any number of lead portions 3 may be provided.

Table 3 shows the calculation of the maximum shear stress generated in the light-transmitting resin end portion 81 (at the same position as the position B of Table 2) by FEM simulation for the optical device housing structures of the fourth, fifth and seventh embodiments The resulting calculation results. Under the same conditions as the FEM simulation through which the results of Table 2 were obtained, the FEM simulation was performed by calculation. Note that the fifth embodiment has a plurality of lenses 8a and a base portion 8b, and calculations are also performed for the luminous resin 8 such that the plurality of lenses 8a and the base portion 8b are separated from each other. In addition, the calculation is also performed for one of the light-transmitting resins 8 having a thickness of 0.5 mm in the fifth embodiment. Furthermore, calculations were performed for the case where a silicone resin was used as the resin contained in the adhesive 10 in the seventh embodiment and the case where the curing point was 75 degrees Celsius. For comparison, Table 3 also shows the calculation results of the first embodiment.

Form 3

Maximum shear stress (MPa) The first embodiment 28 Fourth embodiment twenty three Fifth embodiment (each lens and base part are separated) twenty two Fifth embodiment 25 The fifth embodiment (thin type) 20 The seventh embodiment (silicone resin) 2 The seventh embodiment (curing point: 75°C) 14

It can be clearly seen from Table 3 that compared with the first embodiment, the optical device housing structures of the fourth, fifth and seventh embodiments can further reduce the shear stress of the light-transmitting resin 8 . Therefore, it can be said that the generation of cracks in the light-transmitting resin 8 can be more effectively prevented.

Claims (17)

1. An optical device housing structure, comprising: optics (6); a lead frame having a mounting portion (5) on which the optical device (6) is mounted and a lead portion (3) electrically connected to the optical device (6); a wire (9) located on the side of the lead frame on which the optical device (6) is mounted and electrically connected to the optical device (6) having the lead portion (3); The light-transmitting first resin (8), the light incident on the optical device (6) or the light emitted from the optical device (6) passes through the first resin (8), and the first resin is located in the same position as the optical device (6). The side opposite to the side where the optical device (6) is installed on the lead frame; A second resin (2), at least a part of which is located on the side of the lead frame on which the optical device (6) is mounted, the second resin seals the optical device (6) and the wire (9) and has a smaller coefficient of linear expansion than said first resin; and A crack prevention structure for preventing the first resin from cracking. 2. The optical device housing structure as claimed in claim 1, wherein The anti-crack structure includes: a bent portion (31) positioned at the lead portion (3) of the lead frame and bent toward the side on which the optical device (6) is mounted; A portion (21) of the second resin located on the side opposite to the side on which the optical device (6) is mounted relative to the curved portion (31); and An end portion (81) of the first resin that is in contact with said portion (21) of said second resin on the side opposite to the side where the optical device (6) is mounted. 3. The optical device housing structure as claimed in claim 1, wherein The anti-crack structure includes: a recessed portion (32) located at the lead portion (3) of said lead frame and having a cavity on the side opposite to the side where the optical device (6) is mounted; a portion (22) of said second resin located within the recessed portion (32); and An end portion (81) of the first resin in contact with said portion (22) of said second resin located in the recessed portion (32). 4. The optical device housing structure as claimed in claim 1, wherein The anti-crack structure includes: a bent portion (31) located at the lead portion (3) of said lead frame and bent toward the side on which the optical device (6) is mounted; and An end portion (81) of the first resin with an end surface (83) aligned with the edge of said curved portion. 5. The optical device housing structure according to claim 4, wherein: The end surface (83) of the end portion of the first resin is approximately flush with the surface of the bent portion (31) on the side opposite to the side where the optical device is mounted. 6. The optical device housing structure according to claim 1, wherein: The second resin (2) is formed by transfer molding. 7. The optical device housing structure according to claim 1, wherein: The second resin (2) does not contain any release agent. 8. The optical device housing structure according to claim 1, wherein: The first resin (8) contains a filler for reducing the coefficient of linear expansion of the first resin. 9. The optical device housing structure of claim 1, wherein: said anti-rupture structure comprises said first resin (8), The first resin (8) has a lens portion (8a) for collecting light incident on or emitted from the optical device and a base portion (8b). , the base portion (8b) is connected to the lens portion (8a), and Said base portion (8b) has a thickness not greater than 0.5 mm. 10. The optical device housing structure as claimed in claim 1, wherein said rupturing-resistant structure comprises said first resin (8), and The first resin (8) has a lens portion (8a) for collecting light incident on the optical device (6) or emitted from the optical device (6) and a lens portion extending to the lens portion (8a) of the base portion (8b), and has an area smaller than that of the mounting portion (5) of the lead frame viewed from the emission or incidence direction of the light. 11. The optical device housing structure of claim 10, wherein: The base portion (8b) has a thickness smaller than that of the lens portion (8a). 12. The optical device housing structure according to claim 10 or 11, characterized in that, The second resin (2) has a part located on a side opposite to the side of the lead frame on which the optical device (6) is mounted, and the part (2a) of the second resin is located at least other than the lead frame Place part of the part other than that part of the first resin (8). 13. The optical device housing structure of claim 1, wherein said rupturing-resistant structure comprises said first resin (8), and The first resin (8) has a lens portion (8a) for collecting light incident on the optical device (6) or emitted from the optical device (6) and is connected with the lens portion ( 8a) An associated base portion (8b), and bonding said first resin (8) to at least said lead frame with an adhesive material (10). 14. The optical device housing structure of claim 13, wherein: The binder material (10) comprises a resin having a glass transition point below a minimum storage temperature. 15. The optical device housing structure of claim 13, wherein: The binder material (10) comprises a resin having a curing point not lower than the lowest storage temperature and not higher than the highest storage temperature. 16. The optical device housing structure of claim 1, wherein: said rupture-resistant structure comprises said lower resin (8), and The first resin (8) has a plurality of lens portions (8a) for collecting light incident on the optical device (6) or emitted from the optical device (6) and with respective lens A plurality of base parts (8b) in which the part (8a) is connected, and a plurality of combined parts constituted by the lens part (8a) and the base part (8b) are separated from each other. 17. The optical device housing structure according to any one of claims 1-4, 9, 10, 13 and 16, wherein The mounting portion of the lead frame has an aperture (5a) through which light incident on the optical device or emitted from the optical device passes.

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