JPH02151045A - Connection structure of electronic component and connection and formation of electronic component - Google Patents

Abstract

PURPOSE:To contrive the improvement of the reliability of a connection to a high-density packaging by a method wherein parts having a conductivity and parts having insulation properties are formed simply and selectively in a resin layer to be used for the connection. CONSTITUTION:A resin layer 5 having hardenability to both of light and heat is applied on a substrate 1 and light 7 is directed on this substrate 1 from the rear of the substrate 1. Regions 6, which are irradiated with the light and are hardened, and regions 5, which become selectively unhardened regions as the light is unirradiated, are generated in the resin layer and a metal constituting electrodes 2 discharges the role of a photomask to the resin layer. Then, conductive particles 8 are adhered on the upper parts of the regions 5 on the upper parts of the electrodes 2 and leads 3 on a carrier 4 are aligned and are pressure-welded from the upper part of the carrier 4 to perform the electrical connection between the leads 3 and the electrodes 2. After that, a heating is performed to harden completely the resin layer 5 at the unhardened regions and a connection of an electronic component is completed. Thereby, a highly reliable connection is made possible even in a high-density packaging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a connection structure for electronic components and a method for forming connections for electronic components, and in particular, the present invention relates to a connection structure for electronic components and a method for forming connections for electronic components, and in particular, the connection portions are electrically connected with conductive particles and are insulated. The present invention relates to a connection structure and a connection formation method suitable for a structure adhesively fixed with a synthetic resin.

[Conventional technology]

In recent years, with the increasing density of electronic components, high-density mounting
Highly reliable electrical connections are required to connect various electronic components. For example, in recently developed flat display devices such as liquid crystal display devices and plasma display devices,
Since a driving IC is required for each pixel, needs are increasing as the number of pixels increases and the resolution becomes higher.

Recently, the mainstream electrical connection method for electrically connecting the electrodes on the flat display substrate to external active circuits is to use a conductive anisotropic adhesive in which gold particles are dispersed in a heat-melting adhesive tape. It has become. Although this method is effective in terms of ease of operation and low cost, insufficient consideration has been given to the reliability of inter-electrode insulation and misalignment due to high density.

As a means to solve this problem, for example, Japanese Patent Laid-Open No. 62-1
As described in No. 54746, a method has been proposed in which a conductive part of a hot-melt resin mixed with conductive particles and an insulating part of only a hot-melt resin mixed with nothing are formed in two steps. ing. In this method, a hot-melt paste mixed with conductive particles is printed only on the electrodes, and after drying, a hot-melt insulating adhesive is applied to the connection area, and the Parts or leads are overlapped and bonded under heat and pressure.

[Problem to be solved by the invention]

As in the above-mentioned conventional technology, a connection technology in which a heat-melting conductive paste is formed on an electrode by printing, and then the entire surface including the conductive paste is coated with resin is a connection method using a conductive anisotropic adhesive. more reliable and valid. However, as the distance between the connection terminals becomes shorter (higher density),
There was a problem in terms of reliability because no consideration was given to the fact that the conductive paste flows out when heated and melted, causing adjacent electrode patterns to become dotted and electrically short-circuited.

The purpose of the present invention is to solve this problem, and the first purpose is to provide an improved connection structure for electronic components that enables highly reliable connection even in high-density packaging; The purpose of No. 2 is to provide a method for forming connections between electronic components.

[Means to solve the problem]

The first object is to provide a connection structure for an electronic component, in which a terminal of an electronic component and a terminal portion on a substrate surface are electrically connected using conductive particles and are adhesively fixed using an insulating resin layer. The insulating resin layer is made of a heat- or radiation-curable resin and is formed on the entire surface of the substrate including the terminal portions, and the conductive particles are selectively formed only on the terminal connection portions. This is achieved by a connection structure for electronic components.

As a typical application example, the substrate surface is constituted by a display plate in which a flat display element is formed on the main surface and a drive electrode group is arranged around the periphery, and the drive electrode A connection structure for electronic components, characterized in that the electronic component connected to the group is constituted by a component in which a drive unit incorporating an external drive circuit for driving the display element and a group of electrode terminals thereof are arranged. Accomplished by the body.

The second object is to provide a connection forming method for an electronic component in which a terminal of an electronic component and a terminal portion on a substrate surface are electrically connected using conductive particles and are adhesively fixed using an insulating resin layer. a step of coating and forming an insulating resin layer on the surface of the substrate on which an electrode pattern connecting the electrodes is formed; and a step of coating and forming an insulating resin layer on the substrate except for the area on the electrode pattern of the substrate. a step of selectively curing the layer, and then a step of scattering conductive particles on the substrate to selectively deposit the conductive particles only on the uncured #@marginal resin layer on the electrode pattern. and then, a step of relatively aligning the electronic component so that the connection lead of the electronic component is aligned with the electrode pattern of the substrate, overlapping the electronic component on the substrate, and curing the uncured resin layer under pressure bonding. By a method for forming a connection for an electronic component, the method comprises:
achieved.

As the insulating resin, a known thermosetting or radiation curing resin that is cured by heat or radiation including light can be used. Further, as a method of selective curing, by exposing to heat or light using a mask pattern that blocks heat rays or radiation, selective curing can be performed while leaving an uncured portion corresponding to a predetermined electrode pattern.

If the substrate on which the electrode pattern is formed is made of a light-transmitting insulating material, such as glass or transparent ceramic, and the electrode pattern is made of an opaque conductor, this electrode pattern can be used as a mask. By combining and exposing from its back.

Predetermined selective curing can be achieved in a self-aligned manner without using a special mask. However, if the electrode pattern is made of a transparent conductive layer such as tin oxide or indium oxide, a special mask is naturally required.

Furthermore, in connection between fine electrode patterns, such as in LSI bonding, a highly accurate selective curing technique is required, and it is necessary to realize an uncured area that is faithful to the shape of the mask pattern.

For this purpose, preferably an insulating heat or light absorbing agent (for example a dye or a pigment) is preliminarily added to the resin.
It is effective to dissolve or disperse the liquid to prevent reflection from the substrate, electrode pattern, etc. This can prevent light from going around into the resin on the electrode pattern and shrinking the uncured area, making it possible to achieve highly reliable connections.

As a method for depositing conductive particles on the uncured area of the resin, conductive particle fine powder may be sprinkled by a method such as dusting. It is preferable to carry out the process while the adhesiveness is maintained.

The conductive particles may be any powder with good conductivity, metal powder or conductive oxide powder such as tin oxide or indium oxide, and other materials such as the surface of an insulating material such as a resin ball. So-called microcapsules coated with a conductive substance can also be used.

Note that in applying the insulating resin, any known application method may be used as long as it provides a uniform film thickness, but spin coating or the like is preferred. The thickness of the resin coating must be at least equivalent to the height of the electrode formed on the substrate surface, and preferably, the thickness on the electrode should be approximately equivalent to the average particle diameter of the conductive particles. It is to form. The reason for this is that the uncured areas on the electrodes achieved through selective curing hold the conductive particles, and in the subsequent resin curing process under pressure bonding, serve to bond and fix the two connecting electrode parts. It is.

In other words, it is sufficient to have a sufficient amount of uncured resin to adhesively fix the surface-connected electrode parts.

Conductive particles are sprinkled on the resin in this uncured area, and the two terminals to be connected are aligned, and the uncured resin is cured under pressure and crimping to complete the terminal connection. However, as a resin curing method,
The same curing method as the selective curing process is used. Especially when heated.

If the electrically conductive particles are metal particles and are expected to be oxidized during heating and thereby increase the electrical resistance, the atmosphere in the curing process of the uncured resin should be treated as a non-oxidizing gas atmosphere such as nitrogen gas. This is desirable.

However, when the conductive particles are made of an oxide such as the above-mentioned tin oxide or indium oxide, such consideration is not necessary and normal treatment in air is sufficient.

[For production]

In order to selectively mix the conductive particles only into the resin above the electrode, one method is to selectively harden the resin other than the resin above the electrode, and then mix the conductive particles only into the resin above the electrode in an uncured state.

As the resin for this purpose, a thermosetting resin or a resin that is curable against radiation including light or both radiation and heat is used. When using a thermosetting resin, selective curing is performed using a heat spot such as infrared rays, and when the latter resin is used, light such as ultraviolet rays, other radiation spots such as X-rays and electron beams, or a photomask is used. Especially in the case of a display element such as a liquid crystal display where the element is formed on a glass substrate and the electrodes are made of a light-opaque material such as metal, a photomask etc. By irradiating ultraviolet rays from the back side, only the resin between the electrodes is irradiated with light, and selective curing can be easily achieved.

In this case, since the shape of the electrode itself serves as a mask, curing can be performed in a self-aligned manner without error, without requiring minute alignment.

After that, conductive particles are mixed into the uncured resin on the electrode,
Electronic components or terminals such as leads are pressed together and the entire resin is cured. For curing of this uncured resin, if there are terminals such as leads or electrodes in the connecting portion, and it is impossible or insufficient to irradiate them with radiation such as light, it is preferable to cure the uncured resin with heat. This will cure all parts of the resin and complete the connection.

In the present invention, the electrical connection between the terminals is carried out by conductive particles, and the terminals are fixed by adhesion and fixation of resin. When fixing the connection between these terminals, conductive particles are selectively mixed only into the uncured resin on the electrodes, so even if the pitch between the electrodes is shortened, the subsequent curing process will not be as easy as before. There is very little risk that the electrodes will leak into each other and cause a short circuit between adjacent electrodes. The reason for this is that the resin used in the present invention is not a heat-melting type as in the past, but a thermosetting or radiation-curing resin. In other words,
While conventional connections are made by heating and melting a hardened resin (containing conductive particles) while applying pressure during bonding, the present invention does the exact opposite.
! This is because the areas between the electrodes that are in contact with each other have already been selectively cured and a well-insulated state has been achieved, and the uncured resin on the electrodes is cured (not melted) by heating.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

Example 1 FIGS. 1(a) to 1(f) show process diagrams of the electrical connection method of the present invention.

FIG. 1(a) shows a cross-sectional view of a substrate having electrodes and a group of leads facing each other before connection. As the substrate 1, a glass substrate with a thickness of 1.1 mm was used. After forming a film of about 1100 nm of chromium thereon by direct current sputtering, electrode patterns 2 are formed at a pitch of about 150 p through photolithography and etching steps.

Other well-known conductive metals such as aluminum and copper may be used as the material for the electrode 2, and the film formation method may also be a plating method.

As a lead group, a copper foil layer of approximately 35 mm thick is adhered onto a polyimide tape carrier 4 of approximately 125 mm thick, and its surface is further plated for approximately 5 tIms, and photolithography and etching are performed in the same manner as the electrode 2 above. The leads 3 were formed at the same pitch as the substrate-side electrodes 2 through a process.

FIG. 1(b) is a diagram showing a state in which a resin 5 having curability against both light and heat is applied onto this substrate.

Acrylic resin was used as the resin. The composition is a mixture of hydroxybutyl methacrylate and dicyclopentadiene diacrylate as the main ingredient, 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photopolymerization initiator, and tertiary as a thermosetting catalyst. Several percent of butyl perbenzoate was added to each.

Other resins include, for example, an acrylic resin as a main ingredient, a mixture of 1,1O decanediol dimethacrylate and 2-hydroxyethyl methacrylate, a photopolymerization initiator, 2-hydroxycyclohexylphenyl ketone, and a thermosetting catalyst. , methyl ethyl ketone peroxide, cumene hydroperoxide, etc. can be used.

The coating method uses the spin code method, and the resin thickness is approximately 2-
It was applied so that At this time, if it is made too thick, the difference in thermal expansion with the substrate will cause misalignment during heat cycles, leading to problems such as increased connection resistance. In consideration of this, it is desirable that the thickness be approximately close to the sum of the thickness of the electrode 2 and the average particle size of the particles.

Thereafter, light 7 is irradiated onto this substrate 1 from the back side.

A high-pressure mercury lamp was used as the light source, and ultraviolet light having a wavelength of 365 nm was used. Irradiation energy is approximately 2On+
It was held at J/aiT. As a result, as shown in FIG. 1(C), the resin has a region 6 that is irradiated with light and hardened, and a region 5 that is selectively uncured because it is not irradiated with light. In other words, by irradiating light from the back side, the metal forming the electrode 2 acts as a photomask against the resin.
Only the resin above the electrode 2 selectively becomes an uncured region.

FIG. 1(d) is a diagram showing a state in which conductive particles 8 are attached only to the upper part of the uncured region 5 above the electrode 2.

That is, as shown in FIG. 1(c), conductive particles 8 are sprinkled on the resin that has been selectively cured. In this example, Ni particles having an average diameter of about 2 Im were used as the conductive particles 8. In this case, in the conventional method, the diameter of the conductive particles was required to be the same as or larger than the resin thickness, but in the case of this example, conductive particles can be selectively mixed into the connection part without worrying about the insulation between the electrodes. So.

The diameter of the conductive particles may be small as long as the density is sufficient. If adhesion is insufficient, apply a little pressure at this stage to obtain sufficient adhesion. The conductive particles sprinkled on the hardened area 6 were removed by blowing with nitrogen or by vibrating it horizontally.

FIG. 1(e) and FIG. 1(f) respectively.

FIG. 3 is a diagram showing the alignment of the lead 3 and the electrode 2 and the state in which both are adhesively hardened under pressure. In other words.

As shown in FIG. 1(d), the leads 3 on the tape carrier 4 are aligned over the selectively arranged conductive particles 8, and the leads 3 and electrodes 2 are crimped from above. Make electrical connections, then heat the whole body to 150℃ while keeping it under pressure.
The resin 5 in the uncured area is completely cured by heating for about 60 minutes, and the connection is completed. Note that the pressure during curing was approximately 20 gf per lead.

Example 2 The second example uses antimony oxide-doped tin oxide particles of approximately 1-diameter diameter as the conductive particles, and the steps are the same as in Example 1. In this case, no deterioration in connection resistance due to surface oxidation of the conductive particles was observed even after heat treatment in air at 100°C for 100 hours after connection, and a stable and highly reliable connection was achieved. 6 Example 3 The third example is a case where a material that does not transmit light, such as glass epoxy or a Bakelite substrate, is used as the substrate 1. This will be explained according to the steps shown in FIG. In this case, since the substrate does not transmit light, the light 7 cannot be irradiated from the back surface.

FIG. 2(,) shows a state in which a resin 5 that is hardenable to both light and heat is applied so as to cover the electrode 2 on the substrate 1, as in Example 1. A Bakelite plate with a thickness of about 21 m was used as the substrate, and copper was coated with a thickness of about 10 m. Electrode 2 was formed by plating and patterning by lithography.

FIG. 2(b) is a diagram showing a method of selectively curing the resin 5 using a photomask 9. As the photomask, the chromium metal mask 9' used when forming the electrode 2 can be used as is.

The curing conditions were the same as in Example 1. By using a photomask in this way, even if the substrate is made of a material that does not transmit light, selective curing of the resin is possible as shown in Figure 2(c)6.
The following connection between the electrode 2 and the lead 3 is the same as in Example 1, and will therefore be omitted.

Example 4 The fourth example shows an example in which curing by light cannot be used for some reason, or the electrode is too uneven to use a photomask, and the same substrate as in Example 3 is used. I did it. Hereinafter, a detailed explanation will be given using the process diagram of FIG. 3.

The resin 5 is applied as shown in FIG. 3(a). A thermosetting epoxy resin was used as the resin 5. The resin was then selectively cured by direct writing using an infrared beam 10 from a laser light source (not shown) as shown in FIG. 3(b). In addition, if curing by light is available, selective curing of the resin can also be performed by direct writing with light using a method using an ultraviolet beam. In this way, selective uncured regions 5 could be formed as shown in FIG. 3(c).

The following connection between the electrode 2 and the lead 3 is the same as in Example 1, and will therefore be omitted.

Example 5 An azo dye was dissolved in advance as a light absorber in the resin layer 5 of Example 3 whose process diagram is shown in FIG. 2, and other treatments were carried out in the same manner as in Example 3. The resin was selectively cured with ultraviolet light having a wavelength of 365 nm using a mercury lamp as a light source. the result.

It was possible to form selectively cured regions 6 that left uncured regions 5 faithful to the mask pattern (corresponding to the electrode pattern). The effect of this light absorbing agent was more effective as the electrode pattern became finer, and it was possible to prevent light from going around to the resin on the electrode pattern due to reflection from the edges of the substrate and the electrode pattern. Note that quinoline-based, aminoketone-based, and anthraquinone-based dyes were also effective as this type of light absorber.

Embodiment 6 FIG. 5 shows an example in which the electronic component connection formation technology of the present invention is applied to a liquid crystal display element.

FIG. 5(a) is a plan view showing the external appearance with a partially broken surface.0 As is well known, a liquid crystal display element is a type of flat display element, and the liquid crystal in the corresponding part is driven by vertical and horizontal signal lines. , to display arbitrary figures, characters, etc. There are two types of liquid crystal driving methods: a simple matrix method that uses only the charging and discharging at the intersections of wiring, and an active matrix method that uses switching elements at the intersections.An example of the latter is shown below.

As a switching element, a liquid crystal is sealed between a substrate 1 on which thin film transistors 11 are formed in a matrix, and an upper plate 12. A scanning line 13 for driving the thin film transistor 11. The signal NjA14 is extracted in three directions of the substrate 1. A printed circuit board 15 is fixed so as to surround these three directions. A film carrier 4 on which a driving LS 116 is mounted is placed across the substrate 1 and the printed circuit board 15, and the leads are connected to the substrate 1 and the printed circuit board 1.
5, respectively.

FIG. 5(b) shows an enlarged view of the main part of the thin film transistor matrix.
9!14 to the electrodes. The electrodes are chromium 200nn+ and transparent conductive film (ITO) 100r+ from the bottom.
+w configuration. Further, the electrode pitch is at least 150-.

FIG. 5(c) shows an enlarged cross-sectional view taken along line A' to the connecting portion in FIG. 5(a). A liquid crystal 17 is sealed between a substrate 1 having an electrode 2 connected to a thin film transistor 11 and an upper plate 12, and the gap is sealed with a sealant I8. On the other hand, the film carrier 4 connected to the printed circuit board 15
The driving LS116 is mounted on top. The connection between the board 3 on the film carrier 4 and the electrode 2 is made by the electrical connection forming method of the present invention.A photothermosetting resin similar to that in Example 1 is coated on the electrode 2 to a thickness of about 2 mm. do. After that, 365 Na+ ultraviolet light is irradiated from the back side to selectively harden the resin other than the terminal part, and then conductive particles 8 with a diameter of about 2
- gold-plated styrene balls were sprinkled. In addition, microcapsules having the same structure can also be used. Excess conductive particles were removed by a method such as turning the zero-order substrate upside down and tapping it lightly, or removing it with an air blower.

Then, the leads 3 of the film carrier 4 and the electrodes 2 were aligned and cured at 100'C for 60 minutes while being pressed together. Furthermore, the entire joint was coated with silicone resin 19 for the purpose of increasing the mechanical strength of the joint and corrosion resistance of the joint.

In addition, the method for forming connections for electronic components according to the present invention can also be used for connecting the board 3 on the film carrier 4 and the electrodes on the printed circuit board 15, or for connecting the mount 20 with the driving LS 116.

[Effects of the Invention] According to the present invention, a conductive portion and an insulating portion can be selectively and easily formed in a resin layer used for connection. This formation can be performed after applying the resin to match the electrode pitch, so it can be applied to any electrode shape or electrode pitch, and is effective in terms of workability.

Furthermore, compared to conventional conductive anisotropic adhesives in which conductive particles are uniformly mixed into the resin, the present invention has a higher density of conductive particles at the top of the electrodes, and Since a density distribution is formed in which conductive particles hardly intervene, the conductivity on the electrodes increases and the insulation resistance between the electrodes also increases.

Therefore, it is effective in improving connection reliability for high-density packaging.

Furthermore, heat-melting conductive paste and II! ! Compared to the conventional method in which the conductive particles are applied over the edge resin, since the present invention uses a thermosetting resin or radiation-curable resin, the conductive particles can be fixed on the electrode under pressure bonding. This can be done accurately, and unlike conventional heat-melting resins, there is an extremely low possibility of short-circuiting between adjacent electrodes due to outflow of molten resin during connection. Therefore, high reliability can be achieved in connection between terminals in high-density packaging.

[Brief explanation of the drawing]

FIGS. 1(a) to (f) are cross-sectional views showing the process of connecting electronic components according to an embodiment of the present invention, and FIGS. 2(a) to (c) are sectional views showing the process of connecting electronic components according to another embodiment of the present invention. 3(a) to 3(c) are sectional views showing steps of further different embodiments of the present invention, and FIG. 4(a) is a partially broken external appearance of a liquid crystal display device to which the present invention is applied. A plan view, FIG. 4(b) is an enlarged view of the main part of the thin film transistor matrix incorporated in the liquid crystal display element, and FIG. 4(c) is an A-A' in FIG. 4(a).
FIG. 1... Substrate 2... Electrode 3... Lead 4... Film carrier 5... Resin (uncured area) 6... Resin (cured area) 7... Light 8... Conductive particles 9...Photomask 10...Infrared beam 11...Thin film transistor 12...Top plate 13...Scanning line
14...Signal line 15...Printed circuit board 16
...Drive LS117...Liquid crystal 18
...Sealant 19...Silicone resin 20...
・Mount part 1 Figure 1-111 base plate 2-111 electrode 3-11-lead' 4-----film carrier 5----, )6------
On the right is Rb (Added Ti1) 8--11 lead 1 small particle ↓ No. ↓ No. 7 1--Basic 2--1 electrode 5-1--mfl (Tokyo 4 Otsu) 6----O abandonment R (already rejected) 7----Light 9-1--7 Otomask (α) Fig. 4 Infrared σ-m No. 4

Claims (1)

[Scope of Claims] 1. A connection structure for an electronic component in which a terminal of an electronic component and a terminal portion on a substrate surface are electrically connected by conductive particles and fixed by adhesive with an insulating resin layer, The insulating resin layer is made of a heat- or radiation-curable resin and is formed on the entire surface of the substrate including the terminal portions, and the conductive particles are selectively formed only on the terminal connection portions. Connection structure for electronic components. 2. The substrate surface is constituted by a display plate having a flat display element formed on its main surface and a driving electrode group arranged around its periphery, and the electronic component connected to the driving electrode group. 2. The electronic component connection structure according to claim 1, wherein the electronic component connection structure is constituted by a component in which a drive section incorporating an external drive circuit for driving the display element and a group of electrode terminals thereof are disposed. 3. In an electronic component connection forming method in which the terminal of the electronic component and the terminal portion on the board surface are electrically connected using conductive particles and adhesively fixed with an insulating resin layer, the electrode pattern for connecting the electronic component is formed in advance. A step of coating and forming an insulating resin layer on the surface of the substrate formed on the surface, and selectively curing the insulating resin layer coated and formed on the substrate except for the area on the electrode pattern of the substrate. a step of dispersing conductive particles onto the substrate to selectively deposit the conductive particles only on the uncured insulating resin layer on the electrode pattern; The electronic component is relatively aligned so that the connection leads of the electronic component match, the electronic component is stacked on the board, and the uncured resin layer is cured under pressure bonding. Method of forming connections for electronic components. 4. Connection formation of electronic components according to claim 3, characterized in that in the step of coating and forming the insulating resin layer, an insulating radiation absorbing agent or heat absorbing agent containing light is contained in the resin in advance. Method.