JP2023046305A - Manufacturing method of connection structure - Google Patents

Abstract

To connect a fine electronic component and a substrate using a conductive particle containing film.SOLUTION: A manufacturing method of a connection structure 40 in which a fine electronic component 1 having a length of a longest side of 600 μm or less or an area of each electrode of 1000 μm2 or less is electrically connected with a substrate 20 including an electrode 21 corresponding to an electrode 2 of the electronic component 1 includes: an overlapping step of overlapping the electronic component 1 and the substrate 20 via a conductive particle containing film 10 in which conductive particles 11 are held in an insulating resin layer 12; and a pressurizing and curing step of curing the insulating resin layer 12 of the conductive particle containing film while pressurizing the electronic component and the substrate which overlap via the conductive particle containing film. Regarding curing characteristics of the conductive particle containing film 10, in a case where the conductive particle containing film 10 is heated from 40°C to 80°C, a time from heating start to curing start of the insulating resin layer 12 is 10 minutes or more.SELECTED DRAWING: Figure 8

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a connection structure for reliably electrically connecting fine electronic components that are difficult to handle manually to a substrate.

Fine electronic components have been developed for display applications, for example (Patent Documents 1 and 2). Such minute electronic components are generally manufactured by being separated from a wafer using a dicing tool, and mounted by wire bonding or the like on a glass substrate on which a driver circuit is formed.

On the other hand, when connecting an electronic component such as an IC chip to a substrate, a conductive particle-containing film in which conductive particles are held in an insulating resin layer is used. When an electronic component and a substrate are connected through this conductive particle-containing film, the conductive particle-containing film exhibits conductivity only in the film thickness direction, and is therefore also called an anisotropic conductive film. In recent years, the miniaturization of electronic components has progressed, and in order to adapt the conductive particle-containing film to the miniaturization of electronic components, the ratio of the thickness of the insulating resin layer and the particle size of the conductive particles in the conductive particle-containing film is specified. Or by arranging the conductive particles regularly, or by laminating a resin layer with a high adhesiveness and low hardness to the resin layer containing the conductive particles on the resin layer containing the conductive particles. is performed (Patent Document 3, Patent Document 4). As a result, even micro-sized electronic parts having an electrode area of about 1000 μm ² (eg, 100×10 μm) in electrode rows such as bumps formed on the electronic parts, and even micro-sized semiconductor electrodes can be used. Even if there is, it can be connected to the substrate using a film containing conductive particles.

Japanese Patent Publication No. 2017-521859 Japanese Patent Publication No. 2014-533890 Japanese Patent Application Laid-Open No. 2018-81906 Japanese Patent No. 6688374

The roles required of electronic components are diversifying, and in addition to fine semiconductor elements that were conventionally mounted by wire bonding, etc., it is possible to connect even finer electronic components to substrates using conductive particle-containing films. is needed and the associated issues arise.

For example, conventionally, in an anisotropic conductive connection using a conductive particle-containing film, the number of conductive particles captured in one electrode is 3 or more, preferably 10 or more, from the viewpoint of the stability of electrical properties. is required. However, for example, in the case of anisotropically conductively connecting fine electronic components each having an area of 1000 μm ² or less or a length of the longest side of the electronic component of 600 μm or less, the electrodes themselves are miniaturized. There are situations where it is necessary to be able to do things that are not possible with conventional anisotropic conductive connection specifications, such as 1-3 trapped conductive particles per electrode.

In addition, as the electronic components become extremely small, the number of electronic components connected to the substrate also increases. (Also referred to as a laminating step), a step of stacking electronic components on a conductive particle-containing film provided on a substrate, pressing the electronic component against the substrate through the conductive particle-containing film, and adding an insulating resin layer of the conductive particle-containing film. The difficulty of the connection process, which consists of a curing process that completes the connection of electronic components by pressure curing or heat and pressure curing, increases the difficulty, requires a long time for precise connection, and prevents insulation before the connection is completed. There is a concern that curing of the resin layer may progress unnecessarily.

Accordingly, the present invention provides a film containing conductive particles so that fine electronic parts having an area of each electrode of 1000 μm ² or less or a length of the longest side of the electronic part of 600 μm or less and a substrate can be precisely and reliably connected. The task is to

The present inventor provides a conductive particle-containing film on a substrate, superimposes a fine electronic component and a substrate via the conductive particle-containing film, and pressurizes the superimposed electronic component and the substrate while insulating the conductive particle-containing film. When the resin layer is cured and connected, if the insulating resin layer of the conductive particle-containing film is heated from 40 ° C. to 80 ° C., it takes 10 minutes or more from the start of heating to the start of curing. The inventors have found that the insulating resin layer can be prevented from starting to harden unnecessarily during the period from attachment to connection, and the electronic component and the substrate can be connected precisely and reliably, thereby completing the present invention.

That is, the present invention provides a method for manufacturing a connection structure in which a fine electronic component and corresponding electrodes of a substrate having electrodes corresponding to the electrodes of the electronic component are electrically connected to each other,
A superposition step of superimposing the electronic component and the substrate via a conductive particle-containing film in which the conductive particles are held on the insulating resin layer,
A pressure curing step of curing the insulating resin layer of the conductive particle-containing film while pressing the electronic component and the substrate superimposed via the conductive particle-containing film,
has
The curing property of the conductive particle-containing film provides a production method in which the time from the start of heating to the start of curing of the insulating resin layer when the conductive particle-containing film is heated from 40° C. to 80° C. is 10 minutes or more. .

Further, according to the present invention, a fine electronic component and a substrate having electrodes corresponding to the electrodes of the electronic component are adhered with an insulating resin, and the corresponding electrodes of the electronic component and the substrate are sandwiched between them. Provided is a connection structure electrically connected by one or more but less than three conductive particles.

According to the present invention, as the conductive particle-containing film, a film in which the time from the start of heating to the start of curing of the insulating resin layer when the conductive particle-containing film is heated from 40° C. to 80° C. is 10 minutes or more is used. Therefore, the conductive particle-containing film is provided on the substrate, the fine electronic article is superimposed on the substrate through the conductive particle-containing film, and the insulating resin layer is cured under pressure. is prevented. Therefore, it is possible to accurately connect even minute electronic components with individual electrodes having an area of 1000 μm ² or less or having a longest side length of 600 μm or less to the substrate.

FIG. 1 is a cross-sectional view of a semiconductor component held on a semiconductor processing film. FIG. 2A is a plan view showing particle arrangement of a conductive particle-containing film. FIG. 2B is a cross-sectional view of a film containing conductive particles. FIG. 3A is a cross-sectional view showing a state in which a release film is attached to a semiconductor component on a semiconductor processing film. FIG. 3B is a cross-sectional view of a state in which the film for semiconductor processing is peeled off from the semiconductor component. FIG. 4 is a cross-sectional view showing a state in which the conductive particle-containing film arranged on the substrate is aligned with the semiconductor component attached to the release film. FIG. 5 is a cross-sectional view showing a state in which a semiconductor component and a substrate are overlaid with a conductive particle-containing film interposed therebetween, and the release film is peeled off. FIG. 6 is a cross-sectional view showing a state in which the semiconductor component and the substrate from which the release film has been peeled are pressed from the semiconductor component side with a pressure tool. FIG. 7 is a cross-sectional view of a state in which the conductive particles are sandwiched between the electrode of the semiconductor component and the electrode of the substrate by the first pressurization. FIG. 8 is a cross-sectional view of a state in which the electrode of the semiconductor component and the electrode of the substrate are electrically connected by the second pressurization.

Hereinafter, a method for manufacturing a connection structure according to the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code|symbol represents the same or equivalent component.

<Electronic parts>
Electronic components to be connected by the method of the present invention, for example, each electrode has an area of 1000 μm ² or less, 500 μm ² or less, further 200 μm ² or less, or the electronic component has a longest side length of 600 μm or less, 300 μm or less, or 150 μm. Below, it is a minute electronic component of 50 μm or less. Examples of such electronic parts include various ICs including general driver ICs, semiconductor parts such as optical semiconductor elements, thermoelectric conversion elements (Peltier elements), switching elements, piezoelectric elements, and resistors. Among them, as an optical semiconductor device, a mini-LED whose one side of the chip is about 50 to 200 μm and a μLED whose one side of the chip is less than 50 μm can be mentioned.

FIG. 1 is a cross-sectional view showing a state in which a plurality of semiconductor components are held by a semiconductor processing film 3 as an example of electronic components 1 connected by the method of the present invention. The semiconductor processing film 3 includes known dicing tapes, die bonding tapes, release films, and the like.

In the present invention, it is preferable that the plurality of electrodes on the electrode forming surface of the electronic component 1 have the same height when connecting to the electrodes of the substrate.

The electronic component 1 to be connected by the method of the present invention is fine, for example, the area of each electrode is 1000 μm ² or less, 500 μm ² or less, further 200 μm ² or less, or the length of the longest side of the electronic component 1 is 600 μm or less, 300 μm or less, 150 μm or less, or even 50 μm or less. The shortest side of the electronic component 1 must be of a size that ensures that at least one conductive particle is sandwiched between each electrode. is preferred. Therefore, it is preferable that the shortest side of the electronic component 1 connected by the method of the present invention is 5 μm or more.

The preferred thickness of the electronic component 1 to be connected by the method of the present invention varies depending on the material and strength of the electronic component 1, the height of the electrodes, connection conditions, etc. ² or less, or if the length of the longest side of the electronic component is 600 μm or less, the thickness can be 200 μm or less, or even 50 μm or less, and if the length of the longest side is 300 μm or less, the thickness can be 50 μm or less. When the length of the longest side is 150 μm or less, the thickness can be 30 μm or less; In particular, it can be 10 μm or less. This is because if the ratio of the length of the longest side to the thickness of the electronic component approaches a value of 1, there is a concern that the electronic component may be displaced laterally due to the pressing during connection. In this case, the thickness does not include the height of the electrodes used for electrical connection via the conductive particles.

The height of the electrodes 2 of the electronic component 1 may be substantially zero. The height of the electrode 2 is preferably higher than 1 times the average particle size of the conductive particles so that the conductive particles can be efficiently pushed into the electrodes by pressurization. On the other hand, if the height of the electrode 2 is excessively high, the amount of resin filled between the electrodes will be unnecessarily large. preferable. Alternatively, it is preferably 10 μm or less, more preferably 6 μm or less.

FIG. 1 shows an example in which the semiconductor component 1 held by the semiconductor processing film 3 is used as an example. It does not have to be held on the film for use.

<Substrate>
In the present invention, the substrate 20 for connecting the electronic component 1 may be a transparent substrate such as a glass substrate or a plastic substrate, or may be an opaque substrate. Moreover, as the substrate 20, known electronic components such as a ceramic substrate, a rigid resin substrate, and an FPC can be used.

<Film containing conductive particles>
FIG. 2A is a plan view of an example of the conductive particle-containing film 10 used in the present invention, and FIG. 2B is a cross-sectional view thereof. In the film 10 containing conductive particles, the conductive particles 11 are held by the insulating resin layer 12 .

(Conductive particles)
The conductive particles 11 held in the insulating resin layer 12 in the conductive particle-containing film 10 include metal particles such as nickel, cobalt, silver, copper, gold, and palladium; alloy particles such as solder; metal-coated resin particles; and metal-coated resin particles having insulating fine particles attached to them. Two or more types can also be used together. Among them, the metal-coated resin particles are preferable because the resin particles repel each other after being connected, thereby making it easy to maintain contact with the terminal and stabilizing the conduction performance. Moreover, the surface of the conductive particles may be subjected to an insulating treatment by a known technique so as not to interfere with the conductive properties.

(Particle size of conductive particles)
The particle size of the conductive particles 11 is set to less than 10 μm, preferably 4 μm or less, so that one or more conductive particles can be reliably captured by each electrode even if the electrodes are very small. On the other hand, the thickness is preferably 1 μm or more, more preferably 2.5 μm or more, from the viewpoint of increasing the precision with which the conductive particles 11 are pushed into the electrode. Here, the particle size means the average particle size. The average particle size of the conductive particles 11 in the conductive particle-containing film 10 can be obtained from a planar image or a cross-sectional image. The average particle size may be obtained by measuring the particle size of 200 or more particles by microscopic observation. Further, the average particle size of the conductive particles as raw material particles before being contained in the conductive particle-containing film can be determined using a wet flow type particle size/shape analyzer FPIA-3000 (Malvern). In addition, when fine particles such as insulating fine particles are attached to the conductive particles, the diameter not including the fine particles is defined as the particle diameter.

(Arrangement of conductive particles)
It is preferable that the conductive particles 11 are arranged regularly in the conductive particle-containing film 10 in order to ensure that one or more conductive particles are captured by each electrode of a fine electronic component. It is preferable that they are arranged in a lattice like the conductive particle-containing film described in Document 3. In particular, when the electronic component 1 is obtained by dicing from a wafer, electrodes are formed along the sides of the electronic component 1, so the array of the conductive particles 11 is desirably a rectangular lattice array. . In the conductive particle-containing film 10 shown in FIG. 2A, the conductive particles 11 are arranged in a square lattice.

On the other hand, as the conductive particle-containing film, a film in which conductive particles are evenly and randomly dispersed may be used.

The conductive particles 11 may be embedded in the insulating resin layer 12 or may be exposed. It is preferable that the positions of the conductive particles 11 in the film thickness direction are uniform, and that they are unevenly distributed on one side of the conductive particle-containing film. By being unevenly distributed on one side, pressing is performed evenly, and unexpected movement of particles can be suppressed.

(Number density of conductive particles)
The upper and lower limits of the number density of the conductive particles are not particularly limited because they change depending on the object to be connected. For example, the lower limit of the number density can be 30 pieces/mm ² or more, or 12000 pieces/mm ² or more, or 150000 pieces/mm ² or more, and the upper limit of the number density can be, for example, 500000 pieces/mm ² or less, or 350,000/mm ² or less, or 300,000/mm ² or less.

(Layer structure of insulating resin layer)
The insulating resin layer 12 forming the conductive particle-containing film 10 may be composed of a single insulating resin layer, or may be composed of a laminate of a plurality of insulating resin layers. For example, as the layer structure of the conductive particle-containing film 10, as shown in FIG. , and holding the conductive particles 11 in the high-viscosity resin layer 13 is preferable from the viewpoint of suppressing unnecessary flow of the conductive particles 11 . In this case, the minimum melt viscosity (A1) of the high-viscosity resin layer 13, the minimum melt viscosity (A2) of the low-viscosity resin layer 14, their ratio (A1/A2), and their layer thicknesses are as described in Japanese Patent No. 6,187,665. It can be the same as the known anisotropic conductive film described in JP-A-2018-81906.

(Layer thickness of insulating resin layer)
The lower limit of the layer thickness of the insulating resin layer 12 is preferably 1 time or more, more preferably 1.3 times or more, or 3 μm or more, as large as the particle diameter of the conductive particles. Moreover, the upper limit can be two times or less the particle diameter of the conductive particles or 20 μm or less. When the insulating resin layer 12 is composed of a laminate of a plurality of insulating resin layers, the thickness of the laminate is preferably within these ranges.

The layer thickness of the insulating resin layer 12 can be measured using a known micrometer or digital thickness gauge. In this case, for example, 10 or more points may be measured, and the average value may be taken as the layer thickness.

(Resin composition for insulating resin layer)
The resin composition that forms the insulating resin layer 12 is appropriately selected according to the types of the electronic component 1 and the substrate 20 to be connected by the conductive particle-containing film 10, and may be a thermoplastic resin composition or a high-viscosity adhesive resin composition. , can be formed from a curable resin composition. For example, a curable resin composition formed from a polymerizable compound and a polymerization initiator can be used in the same manner as the resin composition forming the insulating resin layer of the conductive particle-containing film described in Japanese Patent No. 6187665. . In this case, as the polymerization initiator, a thermal polymerization initiator may be used, a photopolymerization initiator may be used, or they may be used in combination. For example, a cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermally polymerizable compound, a photoradical polymerization initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. A thermal anionic polymerization initiator may be used as the thermal polymerization initiator. As the thermal anionic polymerization initiator, it is preferable to use a microcapsule-type latent curing agent comprising an imidazole-modified nucleus and a surface of the nucleus coated with polyurethane.

(Hardening start time of insulating resin layer at 40 to 80 ° C.)
In the conductive particle-containing film 10, the conductive particle-containing film 10 is heated from 40° C. to 80° C. by selecting the type of curable resin composition forming the insulating resin layer 12, adjusting the concentration of the polymerization initiator, and the like. In this case, the time from the start of heating to the start of curing of the insulating resin layer 12 is 10 minutes or more, 20 minutes or more, or further 25 minutes or more. This is because the time from when the insulating resin layer 12 of the conductive particle-containing film 10 is heated in the temperature range of 40° C. to 80° C. to when the insulating resin layer 12 starts to harden is 10 minutes or longer. means that

In addition, when the insulating resin layer 12 is composed of a plurality of insulating resin layers, the time until curing starts means the time until each insulating resin layer starts curing. As a result, after the conductive particle-containing film is provided on the substrate (after the temporary attachment process), even when a large number of fine electronic components are aligned and superimposed on the substrate at the same time and connected by heating and pressing at once, the electronic It is possible to secure 10 minutes or more as the time from the time when the components are stacked on the board, until the electronic components and the board are stacked repeatedly, and finally, the electronic components are stacked on the board and each electronic component is heated and pressurized. , the electronic component and the substrate can be connected precisely and reliably.

In general, the superposing process is performed on the stage of a pressure device heated to about 40°C. Moreover, even when the superimposing process is not performed on the heated stage, there is a case where it is placed on the heated stage before the heating and pressurizing process. Therefore, if the curing start time of the resin composition is short when the conductive particle-containing film 10 is heated at 40 to 80° C., there is a possibility that the resin composition will start curing before the superposing step is completed. On the other hand, by setting the curing start time at 40 to 80° C. to 10 minutes or longer, even if the superimposition process is performed on the stage of the pressurizing device that is heated, the superimposition process can be performed before the start of curing. It is possible to complete.

The upper limit of the time from the start of heating to the start of curing of the insulating resin layer when the conductive particle-containing film 10 is heated from 40° C. to 80° C. is not particularly limited.

In addition, the time until the start of curing is originally set according to the time required for the superimposition process, so that the process of providing the conductive particle-containing film on the substrate and the superimposition process can be performed. It is preferable from the viewpoint of shortening the subsequent pressure curing process, but by setting this time to 10 minutes or more, the application of electronic parts is, for example, smartphones, large-sized televisions, public displays (digital signage), wearable displays. (smart watch), etc., it is possible to sufficiently secure the time necessary for the superimposition process. That is, in general, it takes several seconds to several tens of seconds to superimpose an electronic component such as an IC chip (driver IC) and a substrate via a film containing conductive particles. If there is, this superposition process becomes a precise work. Therefore, for example, fine electronic components such as μLEDs, in which the area of each electrode is 1000 μm ² or less, or the length of the longest side of the electronic component is 600 μm or less, are more difficult to stack than larger IC chips and the like. It is preferable to secure a long period of time. This is because the number of mounted parts increases due to the minute size. The time required for the superimposition process varies depending on conditions such as the method of mounting the components and the apparatus, but as an example, it can take 5 minutes or more, and in some cases 10 minutes or more.

The curing start time of the insulating resin layer 12 of the conductive particle-containing film 10 at 40° C. to 80° C. is 10 minutes or more, or the curing start time is sufficiently long with respect to the time required for the temporary bonding and superimposition steps. Whether it can be called time can be confirmed by, for example, the following (i), (ii), and (iii).

(i) Peeling test of release film In a constant temperature and humidity room with a humidity of 40% RH and a temperature of 30 ° C., a pair of release films are attached to both the front and back sides of the conductive particle-containing film. Remove, attach the surface to a glass plate, place the glass plate on a hot plate set at 45 ° C., press the conductive particle-containing film from the other surface, and correspond to the time required for the overlapping process After a predetermined time has passed, the laminate of the glass plate and the conductive particle-containing film is cooled, and when the release film attached to the conductive particle-containing film is pulled up, the conductive particle-containing film is peeled off from the glass plate. You should check whether Here, it can be seen that when the conductive particle-containing film is peeled off from the glass plate, curing does not proceed within a predetermined time corresponding to the superimposition process. Therefore, it is possible to perform highly accurate alignment between the electronic component and the substrate during this time.

(ii) Temperature measurement by differential scanning calorimeter The reaction start time may be measured from the peak temperature measured when the conductive particle-containing film 10 is heated using a differential scanning calorimeter (DSC). In this case, after processing under heat and pressure conditions (so-called temporary pressure bonding conditions, such as 60 to 80 ° C., 1 to 2 seconds, 0.5 to 2 MPa) in a general overlapping process, the temperature is changed by DSC. may be measured.

As more specific measurement conditions by DSC, the heating rate is set to 10° C./min, preferably 5° C./min, and after reaching 80° C., the holding time is set. The reaching temperature can also be 60°C. In this case, the temperature is raised from room temperature (25° C.±15° C.). The reaching temperature may be 40°C.

In the above measurement operation, it is preferable that the temperature peak (exothermic peak) indicating the initiation of curing between 40° C. and 80° C. does not occur for 10 minutes or longer, and more preferably does not occur for 20 minutes or longer. The term "10 minutes or more" means that when the temperature reaches the range of 40°C to 80°C by raising the temperature from room temperature, the time is 10 minutes or more after reaching 40°C. When it is heated, it means 10 minutes or more from the time when the temperature rise to 60°C starts. If 80°C is reached within 10 minutes, include the time held at 80°C. Simply, it can be tested as the time left in a constant temperature bath set at 80°C.

On the other hand, if this time is excessively long, the latent potential of the polymerization initiator is excessively high, and there is a possibility that the target temperature reduction or shortening time generally cannot be achieved in the curing step by thermocompression bonding. Therefore, the temperature and time for curing the insulating resin layer 12 may be appropriately adjusted according to the time required for the step of superimposing the electronic component and the substrate. In addition, the present invention prioritizes securing the time required for the preceding superposition step rather than achieving the curing step by thermocompression in a short time at a low temperature. It is different from the method of connecting electronic components using the inclusion film.

(iii) Curing Rate of Insulating Resin Layer The fact that the time from heating the conductive particle-containing film 10 to the temperature range of 40° C. to 80° C. to the start of curing is 10 minutes or more means that the conductive particle-containing film 10 is 40% cured. C. to 80.degree. C. 10 minutes after the curing rate of the insulating resin layer 12 is 25% or less, preferably 20% or less. Here, the curing rate can be obtained by measuring the height of a specific peak in the FT-IR chart of the curable resin composition, measuring the exothermic peak area of DSC, or the like.

Regarding the time until the start of curing in the temperature range of 40 ° C. to 80 ° C., the conductive particle-containing film is pre-divided according to the size and arrangement of the μLED on the electrode of the electronic component or the electrode of the substrate by the laser lift-off method. In the case of transferring by using a conductive particle-containing film, the reaction rate after transfer of the curable resin composition constituting the insulating resin layer of the conductive particle-containing film is preferably 25% or less, more preferably 20% or less, and still more preferably 15% or less. and it is preferable to select the type of resin of the curable resin composition, adjust the concentration of the polymerization initiator, etc. so that this is satisfied. When the individual pieces are small, the reaction rate may be measured from the remaining portion of the original film from which the individual pieces were obtained (the edge near the processed portion, etc.).

In addition, the reaction rate (curing rate) of the curable resin composition after 10 minutes from heating the transfer of the conductive particle-containing film by the laser lift-off method from 40 ° C. to 80 ° C. is preferably 25% or less, more preferably. is 20% or less, more preferably 15% or less, so that there is time to place and connect a large number of minute parts, so that the manufacturing conditions are relaxed, contributing to stable productivity. There is expected.

The reaction rate after transfer of the conductive particle-containing film is, for example, using FT-IR, before and after laser irradiation in the laser lift-off method, epoxy group (near 914 cm ^-1 ), (meth) acryloyl group (near 1635 cm ^-1 ), etc. By measuring the peak heights A and a of the reactive group of , and the peak heights B and b of a control such as a methyl group (around 2930 cm ^-1 ), the reduction rate of the reactive group can be obtained by the following equation.

Reaction rate (%) = {1-(a/b)/(A/B)}×100
In the formula, A is the peak height of the reactive group before laser irradiation, B is the peak height of the control before laser irradiation, a is the peak height of the reactive group after laser irradiation, and b is the control peak after laser irradiation. Height.

In the FT-IR measurement, it is preferable to set the sample to an IR detector with a film thickness of 10 μm or less, sandwiched between diamond cells. Moreover, in order to improve the detection sensitivity, it is preferable to cool the IR detector in advance with liquid nitrogen for about 30 minutes. FT-IR measurement conditions are, for example, as follows.
Measurement method: Transmission type Measurement temperature: 25°C
Measurement humidity: 60% or less Measurement time: 12 sec
Spectral range of detector: 4000-700 cm ^-1

When the peak of the reactive group overlaps with another peak, the peak height of the reactive group of the completely cured sample (100% reaction rate) may be set to 0%.

In addition, when the peak height of the reactive group is small, or when the curable resin composition has an alicyclic epoxy group or an oxetanyl group, the reaction rate is calculated by the following formula using HPLC (High Performance Liquid Chromatography). may

Reaction rate (%) = {1-c/C} x 100
In the formula, C is the peak height or area of the reactive component before laser irradiation, and c is the peak height or area of the reactive component after laser irradiation.

In HPLC measurement, it is preferable to extract a sample with a solvent such as acetonitrile and perform gradient elution in which the eluent is continuously changed from X (water/acetonitrile=9:1) to Y (acetonitrile).

By suppressing the reaction rate after the conductive particle-containing film is singulated and transferred to the electrode of the electronic component or the electrode of the substrate as described above, other electronic components can be transferred to the conductive particle-containing film that has been singulated after transfer. It becomes possible to thermocompress the electrodes or the electrodes of the substrate. In addition, singulation may be performed by laser ablation, a laser lift-off method (laser lift method), or other known methods.

(Adhesiveness of film containing conductive particles)
As shown in FIG. 1 , when the electronic component 1 connected to the substrate is adhered to the semiconductor processing film 3 , the adhesive force of the conductive particle-containing film 10 to the electronic component 1 is determined by the semiconductor processing film 3 to the electronic component 1 . Even when the electronic component 1 is adhered to the film 3 for semiconductor processing by increasing the adhesive force of the film 3, the electronic component 1 and the substrate 20 can be temporarily pressure-bonded via the conductive particle-containing film 10.例文帳に追加(FIGS. 4-6).

The adhesive strength of the conductive particle-containing film 10 is determined, for example, by sticking a small piece of the conductive particle-containing film (for example, 0.3 to 1.0 mm wide and 2 cm long) having a release film on one side to the glass substrate. It can be measured by performing a peeling test in which the edge of the peeling film is picked up with tweezers and removed. In this peeling test, when the conductive particle-containing film remains adhered to the glass as success, the n number is 20 or more, preferably 30 or more, and the success rate is preferably 75% or more, preferably 80%. 90% or more is more preferable, and 95% or more is particularly preferable. Since the adhesive force is maintained with high accuracy, the surface of the conductive particle-containing film maintains the holding force necessary for mounting microelectronic parts.

This adhesive force is preferably maintained during the temporary attachment step and the overlapping step.

Further, the adhesive strength can be measured according to JIS Z 0237, as described in JP-A-2019-214714, and by a probe method according to JIS Z 3284-3 or ASTM D 2979-01. It can also be measured as tack force by

Whether the conductive particle-containing film 10 has a high-viscosity resin layer 13 and a low-viscosity resin layer 14 as the insulating resin layer 12 or has a single layer of insulating resin, a probe method for each surface of the conductive particle-containing film For example, the tack force is measured at a probe pressing speed of 30 mm / min, a pressure of 196.25 gf, a pressure time of 1.0 sec, a peeling speed of 120 mm / min, and a measurement temperature of 23 ° C ± 5 ° C. In addition, at least one of the front and back surfaces can be 1.0 kPa (0.1 N/cm ² ) or more, preferably 1.5 kPa (0.15 N/cm ² ) or more, and 3 kPa (0.3 N). /cm ² ) is more preferred.

The adhesive strength of the conductive particle-containing film 10 can also be determined according to the adhesive strength test described in JP-A-2017-48358. In this adhesive strength test, for example, a conductive particle-containing film is sandwiched between two glass plates, one glass plate is fixed, and the other glass plate is peeled off at a peeling speed of 10 mm / min and a test temperature of 50 ° C. In this case, by strengthening the adhesive state between the fixed glass plate and the conductive particle-containing film, the adhesion between the glass plate to be peeled off and the surface of the conductive particle-containing film bonded to the glass plate is increased. measurement becomes possible. The adhesive strength thus measured can be preferably 10 kPa (1 N/cm ² ) or more, more preferably 100 kPa (10 N/cm ² ) or more.

Since the conductive particle-containing film 10 has the adhesive strength described above, the electronic component 1 to be thermocompressed is, for example, smaller than a general IC chip in length of the longest side of 600 μm or less, or an area of each electrode of 1000 μm ² or less. can minimize the problem of misalignment in temporary press-bonding in the superimposition process even for electronic components of .

The production method of the conductive particle-containing film 10 itself is not particularly limited, and can be obtained, for example, by the method described in Japanese Patent No. 6,187,665.

<Connection process between electronic components and substrate>
The production method of the present invention generally includes a temporary attachment step of attaching a conductive particle-containing film 10 to a substrate 20, an electrode 2 of a fine electronic component 1, and a substrate 20 having an electrode corresponding to the electrode 2 of the electronic component 1. A step of superimposing via the conductive particle-containing film 10 (superposition step), while pressing the electronic component 1 and the substrate 20 superimposed via the conductive particle-containing film 10, curing the insulating resin of the conductive particle-containing film 10. It has a step of curing (pressure curing step). In the connection structure obtained by this manufacturing method, the number of electrodes of the electronic component 1 may be one or plural. It can be appropriately determined according to the use of the connection structure.

In addition, between the stacking step and the pressure curing step, if necessary, the electronic component 1 and the substrate 20 stacked with the conductive particle-containing film 10 interposed therebetween are applied with a pressure smaller than that in the pressure curing step. A pre-pressurizing step may be provided in which the conductive particles are sandwiched between the electrodes of the electronic component 1 and the electrodes of the substrate 20 by applying pressure. Hereinafter, the pressurization in the pre-pressurization step will be referred to as first pressurization, and the pressurization in the pressurization and curing step will be referred to as second pressurization.

Moreover, the production method of the present invention can have preliminary or additional steps as necessary.

3A to 8, a manufacturing method according to an embodiment of the present invention including a temporary bonding process, a superimposing process, a pre-pressing process and a pressure curing process will be described. A case of connecting the attached semiconductor component to the substrate 20 will be described. The dicing tape 3 may be replaced with a stamp material for transfer, an adhesive film, a base film with an adhesive layer, or the like.

(1) Alignment process and its preparation process In the method of the present invention, a plurality of electronic components can be connected at once, and as will be described later, the first pressurization and the second pressurization are performed using a pressurization device. However, it is preferable to adjust the number of electronic components to be connected at one time and to align the electronic components so as not to exceed the thrust limit of the pressurizing device.

In order to align the electrodes 2 of the electronic component 1 and the electrodes 21 of the substrate 20, first, as shown in FIG. Then, the dicing tape 3 is separated from the electronic component 1 to expose the electrodes 2 of the electronic component 1 as shown in FIG. 3B. As the release film 4 , it is preferable to use a film having an adhesive force to the electronic component 1 that is smaller than the adhesive force of the conductive particle-containing film 10 to the electronic component 1 .

In this embodiment, an example is shown in which a plurality of electronic components 1 are connected to the substrate 20 at the same time. You don't have to. It may be connected individually, may be selectively connected in multiple pieces in the whole, or may be connected as a whole.

On the other hand, as shown in FIG. 4, the conductive particle-containing film 10 is placed on the surface of the substrate 20 on which the electrodes 21 are to be formed on the stage 31 and is temporarily adhered. In this embodiment, the insulating resin layer 12 as the conductive particle-containing film 10 is a thermosetting high-viscosity resin layer 13 holding the conductive particles 11 and a low-viscosity resin layer laminated on the high-viscosity resin layer 13. 14 of two-layer construction is used. Further, in the film 10 containing conductive particles shown in FIG. Although they also protrude on the viscosity resin layer 13 side, the amount of protrusion on the low-viscosity resin layer 14 side is smaller than the amount of protrusion on the high-viscosity resin layer 13 side, and the conductive particles 11 are substantially held by the high-viscosity resin layer 13 . I am using what I have.

In placing the conductive particle-containing film 10 on the substrate 20 , the description of JP-A-2017-098126 may be applied to selectively place the non-defective portion of the conductive particle-containing film 10 on the substrate 20 .

After the conductive particle-containing film 10 is placed on the substrate 20 and temporarily attached, the electrodes 2 of the electronic component 1 and the electrodes 21 of the substrate 20 are aligned. A known technique can be used as the alignment method, and there is no particular limitation. In the present invention, the insulating resin layer 12 does not start curing before the alignment is completed, so it is possible to perform the alignment precisely.

Also, a method of arranging the conductive particle-containing film 10 on the electrode 21 of the substrate 20, and aligning and arranging the electrode 2 of the electronic component 1 on the conductive particle-containing film 10 arranged on the electrode 21 of the substrate 20 As a method, for example, a known laser lift-off method (for example, JP-A-2017-157724) or according thereto, the conductive particle-containing film 10 is irradiated with a laser beam, and the conductive particle-containing film 10 corresponds to the electrode 21. A piece-like film having an area may be detached and landed on the electrodes 21 , and the electronic components 1 formed vertically and horizontally on the translucent substrate may be irradiated with a laser beam so that the electronic components 1 are connected to the electrodes of the substrate 20 . The droplets may be landed on the conductive particle-containing film on 21 while being aligned. The laser lift-off method can be performed using a commercially available laser lift-off device (for example, Shin-Etsu Chemical Co., Ltd. laser lift-off device, trade name “Invisi LUM-XTR”).

Alternatively, the conductive particle-containing film 10 may be transferred to the electrode 2 of the electronic component 1 or the electrode 21 of the substrate 20 by a transfer method using a known stamp material (eg, JP-A-2021-141160).

(2) Overlapping step Aligned electronic component 1 and substrate 20 are superimposed and placed via conductive particle-containing film 10 according to a known method, for example, as shown in FIG. Then, if necessary, the release film 4 is peeled off. The conductive particle-containing film 10 may be separated into individual pieces in advance.

Although details are not shown, individual pieces of the conductive particle-containing film may be landed on the substrate by the laser lift-off method described above, and μLED may be landed on the conductive particle-containing film. In this case, the size of the individual piece of the conductive particle-containing film is appropriately determined according to the size of the μLED and the electrode. It is also possible to connect several μLEDs in one piece.

In the case where an electronic component such as a μLED is landed on the conductive particle-containing film 10 by a laser lift-off method, the substrate may have a silicone rubber layer, for example, in order to suppress deformation, destruction, displacement of the landing position, etc. of the electronic component. You may The conductive particle-containing film may be singulated and the silicone rubber layer may be polydimethylsiloxane (PDMS).

A conductive particle-containing film or electronic components such as μLEDs are provided or arranged on a silicone sheet such as a polydimethylsiloxane (PDMS) sheet by a laser lift-off method, and transferred to be placed on a substrate. That is, by transferring the state in which the conductive particle-containing film and the electronic component are provided on the silicone sheet to the substrate, the electronic component and the substrate can be superimposed. In other words, even when a conductive particle-containing film is provided or arranged on a substrate using a silicone sheet such as a polydimethylsiloxane (PDMS) sheet by the laser lift-off method, the silicone sheet can be used by the laser lift-off method. Even when electronic components such as μLEDs are provided or arranged on the conductive particle-containing film, the electronic components such as μLEDs on the silicone sheet or the individualized conductive particle-containing film may be transferred. That is, the electronic parts and the substrate can be superimposed by transferring the electronic parts or the individually-divided conductive particle-containing film on the silicone sheet to the substrate. The conductive particle-containing film may be individualized. The laser lift-off method can be used in various modes in carrying out the superimposing process.

In addition, the insulating resin layer 12 constituting the conductive particle-containing film 10 is blended with an inorganic filler such as a cushioning rubber material, silica, talc, titanium oxide, calcium carbonate, magnesium oxide, or the like. The rubber hardness (according to JIS K 6253) by durometer A is preferably 20 to 40, more preferably 20 to 35, still more preferably 20 to 30, and a dynamic viscoelasticity test using an indentation device at a temperature of 30 ° C. , the storage elastic modulus at a frequency of 200 Hz is preferably 60 MPa or less. This is because if the storage elastic modulus is too high, the insulating resin layer of the conductive particle-containing film cannot absorb the impact of the electronic component ejected at high speed by laser irradiation, and the transfer rate of the electronic component tends to decrease.

On the other hand, the storage elastic modulus of the insulating resin layer after laser irradiation at a temperature of 30° C. and a frequency of 200 Hz is preferably 100 MPa or more, more preferably 2000 MPa or more. If the storage elastic modulus is too low, good electrical conductivity cannot be obtained, and connection reliability tends to decrease. The storage elastic modulus at a temperature of 30 ° C. conforms to JIS K7244, in a tensile mode using a viscoelasticity tester (Vibron, A&D Co., Ltd.), for example, at a frequency of 11 Hz and a heating rate of 3 ° C./min. It can be measured under the measurement conditions.

(3) Pre-pressurization step (first pressurization)
In the pre-pressurizing step, as shown in FIG. 6, the electronic component 1 and the substrate 20, which are superimposed with the conductive particle-containing film 10 interposed therebetween, are pressurized from the electronic component 1 side using a pressurizing tool 30. FIG. This first pressurization is performed until the conductive particles 11 contained in the conductive particle-containing film 10 are sandwiched between the electrodes 2 of the electronic component 1 and the electrodes 21 of the substrate 20, as shown in FIG. . It can also be said that the first pressurization holds the conductive particles between the electrodes so that they do not move unnecessarily. By the first pressurization, the distance between the electrode 2 of the electronic component 1 and the electrode 21 of the substrate 20 can be set to 70% or more and 100% or less of the initial particle diameter of the conductive particles 11 sandwiched therebetween. preferable.

The pressurizing force in the first pressing can be, for example, 0.5 to 15 MPa, preferably 2 to 8 MPa. This is appropriately adjusted according to the size of the conductive particles, compressibility (hardness), repulsive force, thickness of the resin layer, and the like.

The temperature at the time of the first pressurization may be heated if necessary, but it is preferably below the starting temperature of the curing reaction of the conductive particle-containing film 10, usually 80 ° C. or below, preferably 55 ° C. or below, It is more preferable to set the temperature to 40° C. or less. There is no particular lower limit, and only pressure may be applied at room temperature (25° C.±15° C.). That is, the temperature during the first pressurization can be the environmental temperature. This pre-pressurization step (first pressurization) may be omitted in some cases.

(4) Pressure curing step (second pressure)
In the pressurization curing step, the second pressurization is performed at a pressure higher than the first pressurization without reducing the pressurization force from the first pressurization. The applied pressure at this time can be 30 to 120 MPa, preferably 60 to 80 MPa. This pressure is adjusted according to the size of the conductive particles, compressibility (hardness), repulsive force, thickness of the resin layer, and the like. As a result, as shown in FIG. 8, the conductive particles 11 sandwiched between the electrodes 2 of the electronic component 1 and the electrodes 21 of the substrate 20 are pressed and flattened, and the electrical connection between these electrodes 2 and 21 is ensured. .

In the pressure curing step, the insulating resin layer 12 is cured to fix the conductive particles 11 sandwiched between the electrodes 2 of the electronic component 1 and the electrodes 21 of the substrate 20, thereby obtaining the connection structure 40 of the present invention. Therefore, when the insulating resin layer 12 is formed of a thermosetting resin, the temperature is raised in the pressure curing step. In this case, the heating is preferably performed in a short time using a pulse heater or the like. The rate of temperature rise is appropriately determined according to the curing characteristics of the insulating resin layer 12. For example, the temperature reached is 100° C. or higher, preferably 120° C. or higher, more preferably 150° C. or higher, and the time to press out is 4 seconds or longer. , preferably 7 seconds or more, more preferably 10 seconds or more. In addition, when the conductive particles are solder, the pressure curing process can be replaced with a reflow process.

Thus obtained connection structure 40 shown in FIG ^. The substrate 20 having the electrodes 21 corresponding to the electrodes 2 of is bonded with the cured product of the insulating resin layer 12 of the conductive particle-containing film 10, and the electrodes 2 of the electronic component 1 and the electrodes 21 of the substrate 20 are They are electrically connected by the conductive particles 11 sandwiched between them.

In the present invention, the number of the conductive particles 11 sandwiched between the electrode 2 of the electronic component 1 and the electrode 21 of the substrate 20 is set to a pair of electrodes 2, 21 facing each other like a general anisotropic connection. The number may be 3 or more, but may be less than 3 or may be 1 as the conductive particles 11 positioned on the pair of electrodes 2 and 21 facing each other reliably contribute to conduction. Therefore, the number density of the conductive particles 11 in the conductive particle-containing film 10 is preferably a number density of 3 or more conductive particles 11 for the pair of electrodes 2 and 12 facing each other. Both less than 3 and 3 or more can be practically used as long as there is no short circuit.

In the above example, the conductive particle-containing film 10 is first placed on the substrate 20 in the alignment step, but in the present invention, the conductive particle-containing film 10 may be placed first on the electronic component 1 .

Although the embodiment in which a semiconductor component is connected to a substrate as the electronic component 1 has been described above based on the drawings, the present invention can be applied to the case of connecting various fine electronic components 1 to a substrate.

1 semiconductor component, electronic component 2 electronic component electrode 3 semiconductor processing film, dicing tape 4 release film 10 conductive particle-containing film 11 conductive particle 12 insulating resin layer 13 high viscosity resin layer 14 low viscosity resin layer 20 substrate 21 substrate Electrode 30 Pressure tool 31 Stage 40 Connection structure

Claims (12)

A method for manufacturing a connection structure in which fine electronic components and corresponding electrodes of a substrate having electrodes corresponding to the electrodes of the electronic components are electrically connected to each other,
A superposition step of superimposing the electronic component and the substrate via a conductive particle-containing film in which the conductive particles are held on the insulating resin layer,
A pressure curing step of curing the insulating resin layer of the conductive particle-containing film while pressing the electronic component and the substrate superimposed via the conductive particle-containing film,
has
The curing property of the conductive particle-containing film is a production method in which the time from the start of heating to the start of curing of the insulating resin layer when the conductive particle-containing film is heated from 40° C. to 80° C. is 10 minutes or more. Between the superposition step and the pressure curing step, the electronic component and the substrate superimposed via the conductive particle-containing film are pressed with a pressure smaller than the pressure force in the pressure curing step, whereby the electronic component is cured. 2. The manufacturing method according to claim 1, further comprising a pre-pressurizing step of sandwiching the conductive particles between the electrode and the electrode of the substrate. 3. The manufacturing method according to claim 1, wherein the conductive particle-containing film is held on the electronic component or substrate by a laser lift-off method. 3. The manufacturing method according to claim 1, wherein the electronic parts are laminated on the substrate by a laser lift-off method. The time from the start of heating to the start of curing of the insulating resin layer when the conductive particle-containing film is heated from 40° C. to 80° C. is adjusted according to the time required for the step of superimposing the electronic component and the substrate. Or the production method according to 2. 3. The production method according to claim 1, wherein the conductive particles are arranged regularly in the conductive particle-containing film. 3. The production method according to claim 1, wherein the conductive particles in the conductive particle-containing film have a particle density such that one or more but less than three conductive particles are captured by each electrode. 3. The manufacturing method according to claim 1, wherein the insulating resin layer is formed of a laminate of two insulating resin layers having different minimum melt viscosities. 3. The manufacturing method according to claim 1, wherein the electronic component is a semiconductor component. 10. The manufacturing method according to claim 9, wherein the semiconductor component to be superimposed on the substrate is adhered to the semiconductor processing film via the conductive particle-containing film. 11. The manufacturing method according to claim 10, wherein the adhesion of the conductive particle-containing film to the semiconductor parts is greater than the adhesion of the semiconductor processing film to the semiconductor parts. An electronic component having a longest side length of 600 μm or less or an electronic component having an individual electrode area of 1000 μm ² or less, and a substrate having electrodes corresponding to the electrodes of the electronic component are bonded with an insulating resin, and the electronic component and A connection structure in which corresponding electrodes of a substrate are electrically connected by one or more but less than three conductive particles sandwiched therebetween.

Images