JP2010135513A - Package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package capable of expanding usability of an optical device while keeping low-cost and high reliability. <P>SOLUTION: The package A has the optical device 10 mounted in a flip-chip state over a mother substrate 1. First and second interconnect pads 5 and 6 are provided on an upper surface of the mother substrate 1, and an opening 1a is formed in the mother substrate 1. On a principal surface side of the optical device 10, a p-type electrode 15 and an n-type electrode 16 are provided. Between the optical device 10 and mother substrate 1, an ACF 30 is interposed which has chain metallic particles 31 dispersed in light-transmissive resin. The p-type electrode 15 and n-type electrode 16, and the first and second interconnect pads 5 and 6 are electrically connected to each other by the chain metallic particles 31 in the ACF 30. The ACF 30 having the chain metallic particles dispersed functions as a path for light in addition to a chip bonding function and an electric connection function. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mounting body on which an optical device including an optical device is mounted, and particularly relates to a measure for improving reliability.

As a method for mounting a semiconductor chip, a method of separately performing chip bonding such as silver paste or solder and electrode connection by wire bonding is generally used.
FIG. 12A shows a procedure of a method using wire bonding as a general mounting method. In the method shown in FIG. 12A, the silver paste 102 is applied on the mother substrate 101, and the semiconductor chip 110 is mounted thereon. In this example, the semiconductor chip 110 is a vertical direction resonant semiconductor laser. The semiconductor chip 110 is provided with an n contact region 112, a mesa region 114 including an active region, a p-type electrode 115, and an n-type electrode 116. After annealing, an electric machine (not shown) on the mother substrate 101 is connected to the p-type electrode 115 and the n-type electrode 116 by bonding wires 121 and 122, respectively.
However, in the above method, there are many steps, and there is a certain limit in reducing the manufacturing cost.

In order to reduce the cost, there is a flip chip mounting method in which chip bonding and electrode connection are performed at once. FIG. 12B shows the procedure of the bare flip chip method. First, a semiconductor chip 110 similar to the semiconductor chip 110 shown in FIG. Then, stud bumps 123 and 124 are provided on the p-type electrode 115 and the n-type electrode 116 of the semiconductor chip 110, respectively. Next, the semiconductor chip 110 is inverted and mounted on the mother substrate 101 in a so-called flip chip state. And each electrode 115,116 and the electrode of the mother board | substrate 101 are joined via stud bump 123,124 by ultrasonic crimping | compression-bonding. This method corresponds to a structure in which the underfill shown in FIG.
This flip chip mounting method has spread mainly in electronic devices such as ICs. However, as described later, the bare flip chip mounting method has a problem in reliability.

FIG. 12C shows a procedure of a flip chip mounting method using underfill (see FIG. 4 of Non-Patent Document 1). First, stud bumps 123 and 124 are provided on a p-type electrode 115 and an n-type electrode 116 of a semiconductor chip 110 similar to the bare flip chip method, respectively. Next, an underfill resin 130 is applied on the mother substrate 101. Next, the semiconductor chip 110 is inverted and mounted on the underfill resin 130 in a so-called flip chip state. And each electrode 115,116 and the electrode of the mother board | substrate 101 are joined via stud bump 123,124 by ultrasonic crimping | compression-bonding. At this time, the underfill resin 130 fills the space between the chip and the mother board including the connection portion.
By interposing the underfill, the difficulty of the bare flip chip method has been solved, and recently, the adoption of this method is being expanded.
Development of flip chip connection technology for consumer products (FIND Vol.20 No.2 / No.3 002 p.6-10) JP 2003-331951 A

By the way, if the flip chip mounting technique is applied to an optical device as it is, various problems occur.
In the case of the bare flip chip shown in FIG. 12 (b), there is a possibility that the active region in the chip is adversely affected by the ultrasonic waves during the pressure bonding. In addition, since the joint portion is only a portion crushed by the pressure bonding of the bump surface, there is a difficulty that the die shear strength against the stress in the lateral direction is weak. This is because there is no member that fills the space between the chip and the mother substrate like silver paste. Also, the electrode having an important function or the chip surface comes into contact with the substrate side member at the time of mounting, and scratches occur. There is a risk of functional deterioration due to oxidation.

When the underfill shown in FIG. 12C is used, since the space is filled with resin, the die shear strength can be maintained. In addition, since the underfill 130 is interposed, damage due to contact with the substrate-side member can be avoided.
However, there is still a possibility that the ultrasonic waves during the crimping may adversely affect the elements in the chip.
In the case of an optical device in a flip-chip state, an opening serving as an optical path is usually provided in the mother substrate 101 for light transmission / reception. Then, the underfill 130 that requires fluidity may flow into the opening and cause trouble. That is, the resin flowing into the opening blocks the opening, thereby causing various problems such as a decrease in light transmission.

  An object of the present invention is to provide a mounting body capable of expanding the usability of an optical device while maintaining low cost and high reliability equivalent to those of a conventional flip chip mounting method.

The mounting body of the present invention is a mounting body in which an optical device having a chip-side conductor in part is mounted on a mounting base having a base-side conductor in part. The optical device is disposed so as to face the mounting substrate and have the chip-side conductor positioned above the substrate-side conductor.
Between the optical device and the mounting substrate, there is an anisotropic conductive film that electrically connects the chip-side conductor and the substrate-side conductor and serves as a light path for entering and exiting the optical device.
The anisotropic conductive film is abbreviated as ACF (Anisotropic Conductive Film). The anisotropic conductive film has no conductivity in the film surface direction (lateral direction) and has conductivity in a direction (vertical direction) substantially perpendicular to the film surface. In general, the anisotropic conductive film is obtained by dispersing conductive particles in an insulating resin.

With this structure, it is possible to emit light generated by the optical device in the direction of the substrate or to enter the optical device from the opposite direction. Conventionally, ACF has been applied to connection of electronic devices unrelated to light and wiring boards. However, since conductive particles (metal particles) are present, the transparency is generally poor, and therefore it has not been considered to transmit light from an optical device using ACF.
On the other hand, the present inventors pay attention to the fact that some anisotropically conductive films have good light transmission properties, and in addition to chip bonding and electrical connection, the anisotropically conductive film has a light transmitting property. I thought of giving the new function of the passage. In other words, it opens up new uses in the field of packaging.
The optical device may be in a flip chip state or may not be in a flip chip state. This is because the mounting body of the present invention can provide a new function of light transmission / reception in addition to chip bonding and electrical connection, which are advantages of the flip chip mounting method, even if it is not flip chip mounting. In the case of an optical device using a transparent wide bandgap semiconductor, it is possible to emit light from the back side.
Unlike the underfill, the anisotropic conductive film is easy to adjust the viscosity to be relatively high. Therefore, even if there is an opening on the mounting substrate side, it is easy to prevent the opening from being blocked. Further, since the connection is performed by thermocompression bonding or ultraviolet irradiation without using ultrasonic waves, the optical device is hardly damaged during mounting.
In addition, since a simple connection method such as thermocompression bonding or ultraviolet irradiation can be employed, the manufacturing cost can be reduced. Further, since the space between the optical device and the mounting substrate is filled with the anisotropic conductive film, the die shear strength can be ensured.
From the above, according to the mounting body of the present invention, it is possible to improve the usability of the optical device while maintaining low cost and high reliability when mounting the optical device.

The anisotropic conductive film preferably has a light transmittance of 60% or more with respect to the used light. According to the experiments by the inventors, it has been found that if the light transmittance is 60% or more, it is easy to use the anisotropic conductive film as a light path.
The light used is generally in the range from visible light to near infrared, that is, about 400 to 1600 nm.

  In particular, the anisotropic conductive film is preferably one in which chain metal particles obtained by chaining metal particles in the vertical direction are dispersed in a translucent resin. As described in Patent Document 1, this is suitable for electrode connection with a narrow pitch, but the light transmittance in the vertical direction is very high because the metal particles are chained in the vertical direction. I understood.

  Further, it has been found that Ni particles are preferable as the metal particles constituting the chain metal particles. By using Ni particles, chain metal particles that are easy to produce chain metal particles and have high functional properties such as high oxidation resistance can be obtained.

  In general, the optical device is preferably arranged in a flip chip state. A light emitting diode (LED), a laser diode (LD) including a vertical cavity surface emitting laser (VCSEL), a photodiode (PD), a solar cell (SC), and the like have a p-electrode and n on the main surface side having an active region. It is often provided with an electrode. Therefore, usually, light is often exchanged from the main surface side of the optical device, and flip-chip mounting with the main surface facing the mounting substrate side is suitable.

  Since the light transmission part with the optical waveguide member is formed in a region located below the optical device on the mounting substrate, the light utilization is further expanded.

  When the light transmission part is an opening, it is preferable to insert an end of an optical fiber as an optical waveguide member into the opening. This makes it easy to exchange light with various external devices. That is, the use expansion as an optical interconnection can be expected.

  According to the mount assembly of the present invention, it is possible to expand the usability of the optical device while maintaining low cost and high reliability.

(Embodiment)
FIG. 1 is a cross-sectional view showing a structure of a mounting body A according to the embodiment.
The mounting body A according to the present embodiment is obtained by mounting the optical device 10 in a flip chip state above the mother board 1 that is a mounting base. On the upper surface of the mother board 1, a first wiring pad 5 and a second wiring pad 6 which are board-side conductors are provided. The mother substrate 1 has an opening 1a for allowing light to pass therethrough.

  On the main surface side of the optical device 10, an operation region 11 including an active region and a cladding layer, a light guide region 12, an oxidized constricting layer 13 sandwiching the light guide region 12 from both sides, and a p contact region 14 are provided. ing. Further, a pair of p-type electrode 15 and n-type electrode 16, which are chip-side conductors, are provided on the main surface side of the optical device 10. Note that the region immediately below the n-type electrode 16 is an n-contact region.

Here, the feature of this embodiment is that an ACF (anisotropic conductive film) 30 is interposed between the optical device 10 and the mother substrate 1. In the present embodiment, the ACF 30 is obtained by dispersing chain metal particles 31 in a light transmissive resin.
The p-type electrode 15 and the first wiring pad 5 are electrically connected by the chain metal particles 31 in the ACF 30, and the n-type electrode 16 and the second wiring pad 6 are electrically connected.

An epoxy resin, an acrylic resin, a polyimide resin, a polyurethane resin, a silicone resin, or the like is used as the light transmissive resin of ACF30. In the case of using an epoxy resin, there are a type that is cured by heating, a type that is cured by light irradiation, and the like.
The chain metal particles 31 in the ACF 30 of the present embodiment are elongated in a string shape and are made of a good conductor metal (Ni). The current flows smoothly in the longitudinal direction of the string-like chain metal particles 31. For this reason, the conductivity between the electrodes 15 and 16 and the pads 5 and 6 can be maintained high. A method for manufacturing the ACF 30 will be described in detail later.
The metal constituting the chain metal particles 30 is not limited to Ni (nickel), but is preferably a magnetic material such as Fe (iron), Co (cobalt), and alloys thereof. However, noble metals such as Au (gold), Ag (silver), Cu (copper), Pd (palladium), and Rh (rhodium) may be used.

The ACF 30 of the present embodiment is characterized in that the light transmittance of the ACF 30 is very high because the chain metal particles 31 that are formed in the vertical direction are dispersed. Therefore, the light generated by the optical device 10 passes through the ACF 30 and exits from the opening 1a of the mother substrate 1 as indicated by an arrow in the figure. Further, the light incident from the opening 1 a passes through the ACF 30 and reaches the optical device 10. That is, the ACF 30 is a light path.
As described above, the ACF 30 functions as a light path in addition to the chip bonding function and the electrical connection function.

FIGS. 3A and 3B are cross-sectional views showing the assembly procedure of the mounting body A according to the present embodiment.
First, as shown in FIG. 3A, the optical device 10 is disposed in a flip chip state above the mother substrate 1, and the ACF 30 is interposed therebetween. At this time, a solid sheet is used as the ACF 30. However, liquid ACF 30 may be applied.
Next, the resin of the ACF 30 is cured by applying a pressing force between the optical device 10 and the mother substrate 1 or by irradiating with ultraviolet rays. Thereby, each electrode 15 and 16 and each pad 5 and 6 will be in a conduction state. When the substrate of the optical device 10 is made of a material that transmits ultraviolet rays, such as sapphire and bulk GaN, an ultraviolet irradiation type can be used.
Through the above steps, the mounting body A shown in FIG. 3B is obtained. The mounting body A is as already described.

According to the present embodiment, the following effects can be exhibited.
In this embodiment, the ACF 30 functions as a light path in addition to the chip bonding function and the electrical connection function. Of these, the chip bonding function and the electrical connection function are satisfied even in the conventional flip chip mounting method. Therefore, a comparison between the conventional flip chip mounting method and the mounting method of the present embodiment is as follows.
As described above, the mounting process of the present embodiment is very simple. Therefore, like the conventional flip chip mounting, the manufacturing cost can be kept low. Moreover, since the space between the optical device 10 and the mounting substrate 1 is filled with the ACF 30, die shear strength can be ensured. Further, since the connection is performed by thermocompression bonding or ultraviolet irradiation without using ultrasonic waves, the optical device 10 is hardly damaged during mounting.
The above points are equivalent to the conventional flip chip mounting method using the underfill. That is, it has an advantage over the bare flip chip mounting method.

  On the other hand, when an underfill is used in the conventional flip chip mounting method, there is a risk of damaging the device by using a gold stud bump and performing ultrasonic bonding. On the other hand, when the ACF 30 of the present embodiment is used, it is only necessary to perform pressure application and thermal curing or curing by ultraviolet irradiation. That is, since the application of ultrasonic waves is unnecessary, the damage wave of the device hardly occurs.

In addition, if the underfill in the conventional flip chip mounting method is to function as a light path, problems such as blocking the opening 1a of the mounting substrate 1 occur.
On the other hand, the ACF 30 is a solid sheet, so that even if the mounting substrate 1 has the opening 1a, the opening 1a is not blocked. Therefore, as will be described later, it is also easy to insert and receive light from an external device by inserting an optical fiber into the opening 1a. Therefore, the conventional problems can be solved.

  From the above, the mounting body A using the ACF 30 can improve the usability of the optical device 10 while maintaining low cost and high reliability when mounting the optical device 10.

  Further, by using the ACF 30, it is possible to eliminate bumps necessary for normal flip chip mounting (see FIGS. 1 and 3). Therefore, the manufacturing cost can be further reduced by eliminating the bumps.

  In particular, in this embodiment, ACF 30 in which chain metal particles are dispersed is used. With this configuration, the light transmittance is drastically improved as compared with the case where commonly used metal particles are dispersed in a resin. Therefore, the ACF 30 of the present embodiment can exhibit a particularly high function as a light path.

In this embodiment, a vertical cavity surface emitting laser (VCSEL) is used as the optical device 10, but the optical device is not limited to this. The optical device may be a light receiving element such as a semiconductor laser having another structure or a photodiode (PD).
However, a light emitting diode (LED), a laser diode (LD) photodiode (PD) including a vertical cavity surface emitting laser (VCSEL), a solar cell (SC), and the like have a p-electrode on the main surface side having an active region. Since it often includes an n-electrode, it is particularly suitable for the present invention.

-Modification of the embodiment-
FIG. 2 is a cross-sectional view illustrating a structure of a mounting body A according to a modified example of the embodiment.
In FIG. 2, members having the same functions as those in FIG. In this modification, the structures of the optical device 10 and the mounting substrate 1 are the same as those in the embodiment, and only the structure of the ACF 30 is different.
In this modification, the ACF 30 is obtained by dispersing spherical metal particles 32 in a resin having optical transparency. While applying a pressing force between the optical device 10 and the mother substrate 1, the resin of the ACF 30 is cured by heating or irradiating with ultraviolet rays. Then, the metal particles 32 existing between the electrodes 15 and 16 and the pads 5 and 6 are connected. Thereby, each electrode 15 and 16 and each pad 5 and 6 will be in a conduction state.

  Also according to this modification, the same effect as the embodiment can be obtained if the light transmittance of the ACF 30 is sufficiently high. However, the metal particle 32 having a considerable size in the lateral direction has a higher light blocking ratio than the chain metal particle 31 in the embodiment. Moreover, like the metal particle 32a shown in FIG. 2, the metal particle 32a crushed between the electrode and the wiring pad greatly spreads in the lateral direction. Therefore, the transmittance of the ACF 30 of this modification is lower than that of the embodiment.

4A and 4B are diagrams showing the relationship between the concentration of the chain Ni particles as the chain metal particles 31 and the light transmittance (visible region) of the ACF 30, and the wavelength dependence of the light transmittance. FIG. In the experiments by the inventors, the reliability of electrical connection can be ensured even when the chain Ni concentration is about several percent. Further, it has been found that if the light transmittance is 60% or more, the operation of the optical device or the optical device can be secured.
As shown in FIG. 4A, in the case of the ACF containing the chain Ni particles of the present embodiment, the particle concentration-permeation rate characteristic as shown by the solid line Lnc is shown. When the transmittance is limited to a range of 60% and the solid line Lnc is approximated to a linear characteristic line, a broken line Lni is obtained.
FIG. 4B evaluates the wavelength dependence of the non-cultivation transmittance when an ACF having a transmittance of 80% in which chain Ni particles are dispersed is thermally cured. As can be seen from the figure, sufficient transmission characteristics are shown in a wide wavelength range from visible light to near infrared light.
On the other hand, in the case of ACF containing metal particles currently on the market, the particle concentration is unknown, but the light transmittance is a little over 30% (see dotted line Lpa). However, the dotted line Lpa does not mean that the light transmittance is constant even if the particle concentration increases.
Therefore, even in the above-described modification example, by adjusting the material, shape, dispersibility, etc. of the metal particles so that the light transmittance is 60% or more within the range in which the electrical connection can ensure electrical connection. You can get the basic effect of form.

As Example 1, the characteristics of a surface emitting laser (VCSEL) and a light receiving optical device on an optical fiber connecting ferrule were examined. 5A to 5C are plan views showing the structures of the optical device, the mounting substrate (mounting base), and the light receiving PD used in Example 1 in order.
As shown in FIG. 5A, the optical device is a vertical cavity surface emitting laser (GaAs VCSEL) having a light emitting portion, a p electrode, and an n electrode on the main surface side.
As shown in FIG. 5B, the mounting substrate has an opening for inserting a multimode optical fiber (120 μm diameter). The mounting board includes a p-electrode and an n-electrode having a pitch of 125 μm and the same width.

On the mounting substrate, a chain Ni particle-dispersed ACF (transparent epoxy base material) was pasted so that the entire surface of the optical device was covered (the pasting area was larger than the dotted line). The ACF is adjusted to have a thickness of 15 μm and a transmittance of 80% in the infrared region (near 850 nm). Next, the optical device was mounted on a mounting substrate in a flip chip state so that the electrode patterns face each other. Then, while heating to 190 ° C. and applying a pressure of 0.3 N and holding for 30 seconds, the optical device was strongly bonded to the substrate. Further, an optical fiber was inserted from the lower surface side of the mounting substrate, and current was injected into the optical device through the electrode pattern of the mounting substrate.
6A and 6B are diagrams showing ILV measurement and optical output-wavelength characteristics in Example 1. FIG. As shown in FIG. 6A, a light output of 1 mW was observed at the output end of the optical fiber when a current of 8 mA was applied. Further, as shown in FIG. 6B, the wavelength showing the maximum peak of the optical output is in the vicinity of 850 nm.
The die shear strength was recorded as 100 g or more.

  Further, as Comparative Example 1, a mounting body was prepared on which flip chip mounting using a general-purpose ACF was performed. The basic structure of Comparative Example 1 is the same as that of the mounting body A shown in FIG. The ACF used in the comparative example is ACF (15 μm thickness, transmittance of about 30%) in which spherical fine metal particles are dispersed and mixed.

  Further, as Comparative Example 2, a mounting body by bare flip chip mounting was prepared. FIG. 7 is a cross-sectional view of the mounting body X according to Comparative Example 2. The mounting body X includes the optical device 10 and the mother board 1 similar to those in the first embodiment. However, ACF is not used, and a gold stud bump 34 having a diameter of 20 μm is formed on the optical device 10 side. And the gold stud bump 34 and the 1st, 2nd wiring pads 5 and 6 were joined by the ultrasonic wave directly in the state heated to 200 degreeC. And the optical fiber was inserted in the opening 1a and the electricity supply test was done. Thus, the structure in which the optical fiber is inserted into the opening is called a ferrule.

The measurement results for Comparative Examples 1 and 2 are as follows.
In Comparative Example 1, it was found that the fiber end output when the current of 8 mA was applied was 0.1 mW or less, and the necessary light output could not be obtained at all.
In Comparative Example 2, the fiber end output when the current of 8 mA was applied was 1.2 mW, which was almost the same as Example 1. However, it was found that the die shear strength is only 20 g, which is poor in reliability.

Furthermore, in Example 1, a photodiode (PD) having a light receiving portion, p-electrode, and n-electrode pattern as shown in FIG. 5C was prepared as an optical device. This PD is also mounted using a chain Ni-dispersed ACF. The ACF is adjusted to have a thickness of 15 μm and a transmittance of 80% in the infrared region (near 850 nm).
FIG. 8A is a diagram schematically showing a coupling unit in which the VCSEL mounting body of Example 1 and the PD mounting body are connected via an optical fiber. When this optical communication unit was operated, it succeeded in obtaining a sufficiently strong signal from the PD. This coupling unit can be said to be a highly reliable optical interconnection unit that is completely free of Wibon.
At this time, the optical fiber functions as an optical waveguide member. And the opening 1a of the mother board | substrate 1 is a light transmission part with an optical waveguide member.

FIG. 8B is a diagram illustrating a structure provided with an optical waveguide member in another example of the first embodiment. In this structure, an optical waveguide member 40 is provided on the upper surface of the mother substrate 1. The optical waveguide member 40 is a rod-shaped member made of, for example, PMMA (polymethyl methacrylate) resin. An inclined surface 41 is formed at the tip of the optical waveguide member 40 as a light transmission part that receives light emitted from the VCSEL.
Even with such a structure, optical communication between the external device and the VCSEL (optical device) can be performed via the optical waveguide member 40.

Next, Example 2 according to a mounting body in which an ultra-low profile device (LED) is provided on a printed board will be described.
FIGS. 9A to 9C are a plan view of the LED and the mounting board according to the second embodiment, and a cross-sectional view of the mounting body, respectively.
As shown to Fig.9 (a), LED of a present Example is a blue light emitting diode (GaN-type LED) which has p electrode and n electrode in the main surface side. The chip size is 300 μm square and the thickness is 60 μm, and a GaN layer epitaxially grown on a transparent sapphire substrate is used.
As shown in FIG. 9B, the mounting side substrate is an ultra-thin printed board having a p-electrode and an n-electrode and a thickness of 80 μm.

An LED was mounted on the mounting substrate using a chain Ni-dispersed ACF (transparent silicone base material). The ACF is 10 μm thick and is adjusted so that the transmittance in the visible region (near 450 nm) is 80%.
The LED was flip-chip mounted, the electrodes were opposed to each other, and mounted on a mounting substrate with an ACF interposed therebetween. While heating at 190 ° C. and applying a pressure of 0.5 N and holding for 30 seconds, the LED was strongly bonded to the substrate.
Further, a silicone resin was poured over the entire surface of the LED by a potting method, resin sealing was performed, and the entire mounting substrate was cut to 1608 size.
FIG. 9C2 is a cross-sectional view of the completed mounting body. FIG. 9C1 is a cross-sectional view of the mounting body of the comparative example. In this comparative example, wire bonding is used and chip bonding is performed by underfill. FIG. 9 (c1) and FIG. 9 (c2) are shown on the same scale in order to compare the dimensions.

With the mounting body according to Example 2 shown in FIG. 9C2, the dimensions can be greatly reduced as compared with the mounting method using wire bonding.
In addition, since the transparent sapphire substrate is used, as shown by the arrow in FIG.9 (c2), the light emitted from both surfaces of LED can be utilized efficiently. That is, by providing a mirror film on the mother substrate, the light emitted from the LED to the main surface side can be reflected upward, and the light emitted from the LED to the back surface side can be emitted from the back surface as it is.

When a current was injected into the LED through the electrode pattern on the mounting board of the mounting body of this example, a total light output of 2 mW was observed with an integrating sphere when a current of 5 mA was applied.
The thickness of the mounting body according to the present example is only 0.16 mm. The 0.2 mm which was the minimum thickness record of the low-profile LED mounting body mounted using the silicone adhesive and wire bonding so far has been greatly updated.
In addition, the LED of this example, when combined with light extraction from the transparent sapphire substrate side, obtained a light output of 1.2 mW at a current of 5 mA. This updates the light output record of a conventional low profile LED.

(ACF manufacturing process)
Next, the manufacturing process of ACF in which chain metal particles are dispersed in the above embodiment will be described. FIG. 10 is a perspective view showing an ACF manufacturing process.
First, a resin liquid in which Ni particles are dispersed is applied on a base film. Then, the base film and the resin liquid are passed through a Ni particle aligner in which magnets are vertically arranged in a drying furnace. Thereby, magnetized Ni particles are connected to each other in a string shape, and chain Ni particles (chain metal particles) are formed.
By drying the resin liquid in the drying furnace, the resin is solidified, and the shape and position of the chain Ni particles are fixed in the resin. Thereby, ACF is formed.
Thereafter, the ACF is laminated from above and below through a film thickness inspection and an orientation inspection, and a resin sheet ACF is completed.

In the lower part of FIG. 10, SEM photographs before and after orientation of the Ni particles are displayed. Before orientation, fine Ni particles are densely dispersed. After the orientation, the Ni particles gather to form a chain of Ni particles, and the interval between the chain Ni particles is increased.
That is, before the orientation, the Ni particles are densely dispersed, so that the light transmittance of the resin film is not high. From this, it seems that the idea of making the conventional ACF function as a light path did not occur.
On the other hand, after the orientation, it can be seen that the light transmittance of the resin film is remarkably improved by increasing the interval between the chain Ni particles. The present inventors paid attention to this point.

  FIGS. 11A and 11B are a SEM photograph and a 3D-FIB diagram showing a structure before and after performing interelectrode connection of ACF in which chain Ni particles are dispersed. As shown in FIG. 11B, it can be seen that chain Ni particles are interposed between the upper electrode and the lower electrode, and both are electrically connected.

  As described above, the production process of ACF in which chain metal particles are dispersed is simple and does not require a particularly expensive apparatus. Therefore, the manufacturing cost is not so high as compared with the conventional ACF in which spherical metal particles are dispersed. Therefore, a low cost can be maintained as compared with the step of performing wire bonding.

(Other embodiments)
In the above embodiment and each example, the optical device is flip-chip mounted. However, the mount assembly of the present invention is not necessarily limited to the flip-chip mount. In a surface emitting laser or the like using bulk GaN, a p-electrode is provided on the main surface side of the substrate and an n-electrode is provided on the back surface side. Further, when using laser light emitted from the active region up and down, the flip chip mounting is not necessarily required. Even in such a case, since the ACF serves as a light path, the usability of the optical device is increased, and the number of wire bondings can be reduced only on one side. Furthermore, it is possible to draw out the upper surface electrode to the back surface side using a through hole. Even in such a case, if the optical device uses a transparent substrate, the ACF can function as a light path.
Therefore, the basic effect of the present invention of expanding the usability of the optical device while maintaining low cost and high reliability can be exhibited.

  The structure of the embodiment of the present invention disclosed above is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The mount assembly of the present invention can be used for mounting optical devices such as laser diodes, photodiodes, and solar cells.

It is sectional drawing which shows the structure of the mounting body which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the mounting body which concerns on the modification of embodiment of this invention. (A), (b) is sectional drawing which shows the assembly procedure of the mounting body which concerns on embodiment. (A), (b) is a figure which shows the relationship between the density | concentration of chain-like Ni particle-light transmittance (visible region), and the figure which shows the wavelength dependence of light transmittance. (A)-(c) is a top view which shows the structure of the optical device, the mounting board | substrate (mounting base | substrate), and light receiving PD which were used in Example 1 in order. (A), (b) is a figure which shows the ILV measurement in Example 1, and an optical output-wavelength characteristic. 6 is a cross-sectional view of a mounting body according to Comparative Example 2 of Example 1. FIG. (A), (b) is sectional drawing which shows the example of the mounting body provided with the optical waveguide member which concerns on Example 1 and its another example in order. (A)-(c2) is the top view of LED which concerns on Example 2, and a mounting board in order, and sectional drawing of a mounting body in order. It is a perspective view which shows an ACF manufacturing process with the orientation display photograph of Ni particle | grains. (A), (b) is a microscope picture figure which shows the structure before and behind performing the connection between electrodes of ACF which disperse | distributed chain | strand-shaped Ni particle | grains. (A)-(c) is sectional drawing which shows the procedure of the mounting method using wire bonding, the US flip chip mounting method, and the flip chip mounting method using an underfill in order.

Explanation of symbols

1 Mother board (mounting substrate)
1a Aperture (light transmission part)
DESCRIPTION OF SYMBOLS 5 1st wiring pad 6 2nd wiring pad 10 Optical device 11 Operation area | region 12 Optical guide area | region 13 Oxide constriction layer 14 p contact area | region 15 p-type electrode 16 n-type electrode 30 ACF (anisotropic conductive film)
31 Chain metal particles 32 Metal particles 34 Gold stud bump

Claims (7)

A mounting body in which an optical device having a chip-side conductor in part is mounted on a mounting base having a base-side conductor in part,
The optical device is disposed so as to face the mounting substrate, and the chip-side conductor is positioned above the substrate-side conductor,
Between the optical device and the mounting substrate, there is an anisotropic conductive film that electrically connects the chip-side conductor and the substrate-side conductor and serves as a path for light entering and exiting the optical device. An implementation body. The mounting body according to claim 1,
The anisotropic conductive film has a light transmittance of 60% or more with respect to used light. The mounting body according to claim 2,
The anisotropic conductive film is a mounting body in which chain metal particles formed by chaining metal particles in the vertical direction are dispersed in a translucent resin. The mounting body according to claim 3,
The mounting body, wherein the metal particles of the chain metal particles are Ni particles. In the mounting body according to any one of claims 1 to 4,
The optical device is a mounting body arranged in a flip chip state. In the mounting body according to any one of claims 1 to 5,
A mounting body in which a light transmission part with an optical waveguide member is provided in a region located below the optical device in the mounting substrate. The mounting body according to claim 6,
The light transmission part is an opening,
A mounting body in which an end of an optical fiber as the optical waveguide member is inserted into the opening.