JPH0714625A - Wiring structure and manufacture thereof - Google Patents

Abstract

PURPOSE:To stabilize connection over a long period of time by arranging electrode terminals formed respectively on two wiring boards opposite to each other, and connecting both electrode terminals electrically to each other by an UV light transmissive conductive member dispersed in an UV light-curing adhesive. CONSTITUTION:An electrode terminal 2 formed on an electric circuit board 1 and an electrode terminal 4 formed on an electric circuit board 3 are arranged opposite to each other, and the electrode terminals 2 and 4 are adhered together by an UV light-curing adhesive 6 in which an UV light transmissive conductive member 5 is dispersed. Thereby, when UV light is radiated, since the conductive member 5 passes the UV light, the adhesive 6 can be all hardened firmly, and the terminals 2 and 4 are connected electrucally to each other by the conductive member 5. Thereby, connecting reliability between the electrode terminals is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure and a method for manufacturing the same, and more particularly, to an electric circuit component (wiring board) such as an external circuit such as a TAB used in a liquid crystal display.
The present invention relates to a wiring structure that can be applied to the connection technology of (1) and can stabilize the connection reliability between conductive particles and electrode terminals for a long period of time, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a method of manufacturing a wiring structure is as follows.
For example, there is one reported in Japanese Patent Application Laid-Open No. 60-262430, in which a metal bump of a semiconductor element and a wiring pattern of a circuit board which opposes the metal bump are connected by a curing shrinkage force of a photocurable resin. With such a configuration, there is an advantage that strain due to expansion of the circuit board due to temperature and mechanical strain can be made difficult to directly act on the semiconductor element itself.

In the method of interconnecting electrode terminals reported in Japanese Patent Laid-Open No. 3-289070, for example, conductive terminals are selectively arranged on electrode terminals on which an adhesive is formed to obtain a connection. Specifically, the electrode terminals of the first electric circuit substrate and the electrode terminals of the second electric circuit substrate are electrically connected to each other through conductive fine particles, and the electrode terminals are held and fixed by an adhesive. In the method, an adhesive is formed on the electrode terminals protruding from the surface of at least one of the electric circuit substrates, and conductive fine particles are adhered to the adhesive, and then the first electric circuit substrate and the second electric circuit substrate. By using an insulative adhesive for pressure contact and connection, it is possible to connect the electrode terminals arranged in high density while maintaining the electrical insulation of the adjacent electrode terminals.

In the conventional metal bump structure, since the substrate and the electrode terminal are easily damaged, elastic conductive particles are placed on the electrode terminal and the periphery thereof is bonded with a UV adhesive to connect the electric circuit board. Was there. The process will be described below with reference to the drawings. First, as shown in FIGS. 4A and 4B, in order to selectively dispose the UV curable adhesive 33 on the electrode terminals 32 of the electric circuit board 31, the UV curable adhesive is adhered on the flat substrate 34. After applying the agent 33 uniformly, the circuit board 31 and the flat board 34 are pressed so that the electrode terminals 32 are pressed against the UV curable adhesive 33.
4C, the circuit board 31 is peeled off from the flat board 34, and the UV curable adhesive 33 is transferred onto the electrode terminals 32 of the circuit board 31, as shown in FIG. 4C. Then, as shown in FIG. 4D, the conductive particles 36 are two-dimensionally regularly arranged on another flat substrate 35. At this time, if the conductive particles 36 are not individually arranged, it is not preferable because it may cause a leak between the electrodes after connection, so the conductive particles 36 are adjusted so as to be arranged individually.

Next, as shown in FIG. 5A, a flat substrate
Electrode terminals 32 of circuit board 31 on conductive particles 36 arranged on 35
The UV curable adhesive 33 on the upper side is pressed, and UV is applied while pressing the circuit board 31 so that the electrode terminals 32 and the conductive particles 36 contact each other.
By irradiating light from the back surface of the transparent flat substrate 35 to cure the UV curable adhesive 33 with the electrode terminals 32 and the conductive particles 36 in contact with each other, the circuit substrate 31 is peeled off from the flat substrate 35. As shown in FIG. 5B, the conductive particles 36 are arranged and fixed on the electrode terminals 32 of the circuit board 31 by the UV curable adhesive 33.

Then, the transparent electrode 37 facing the circuit board 31.
After the UV adhesive is applied to the circuit board 38 (or the electric circuit board with the conductive particles or the like) on which the conductive particles 36 are fixed, the conductive particles 36 fixed to the electrode terminals 32 of the circuit board 31 are on the transparent electrode 37 of the circuit board 38. The circuit board 31 and the circuit board 38 while aligning them with each other, and irradiating UV light from the rear surface of the transparent circuit board 38 to cure the UV adhesive 39 to cure the circuit board 31 and the circuit board 38. A wiring structure as shown in FIG. 5C can be obtained by connecting the wirings.

[0007]

However, in the conventional wiring structure as described above, since the conductive particles are metal particles such as Ni or carbon particles, or particles obtained by applying a metal coating to plastic particles, light is reflected. Alternatively, since it is absorbed, when UV light is applied to the UV curable adhesive 33 from the back surface of the transparent flat substrate 35 in the step of FIG. It was easy for the UV curable adhesive 33 between the conductive particles 36 and the conductive particles 36 to become uncured. More specifically, as shown in the enlarged view of FIG.
Since the light is radiated from the direction perpendicular to the surface of the electrode terminal 32, the shadow of the conductive particles 36 is not radiated, and the UV curable adhesive is used.
The uncured portion 33b of 33 is left. Therefore, in the initial stage or under a certain environment, as shown in FIG. 6B, the conductive particles 36 float and a non-contact portion A with the surface of the electrode terminal 32 is generated.
There has been a problem that the connection resistance value between the electrode terminal 32 and the electrode terminal 32 rises or is opened.

As described above, in the conventional wiring structure, since the conductive particles 36 are made of a material that hardly transmits UV light, the conductive particles 36 and the electrode terminals 32 are formed as shown in FIG. 5A. When UV light is applied while applying pressure,
As shown in (a), there is no conductive particles 36,
The portion irradiated with the V-curable adhesive 33 is cured to be the cured portion 33a. As described above, since the conductive particles 36 hardly transmit UV light, the portion of the conductive particle 36 which is not irradiated with UV light. Is not cured and becomes an uncured portion 33b.

Therefore, since the electrode terminal 32 and the conductive particle 36 are connected by the uncured portion 33b, the adhesive strength is weak and the electrode terminal 32 and the conductive particle 36 are easily peeled off as shown in A of FIG. There was a problem in terms. Specifically, if thermal stress, mechanical stress, or the like is applied after the bonding, the connection between the electrode terminal 32 and the conductive particles 36 becomes unstable and the resistance value rises, or in the worst case, as shown in FIG. ), The conductive particles 36 may be peeled off from the electrode terminal 32 and broken.

Therefore, according to the present invention, the UV adhesive between the conductive particles and the electrode terminals can be hardened to firmly bond the conductive particles and the electrode terminals, and even if thermal stress or mechanical stress is applied, It is an object of the present invention to provide a wiring structure and a manufacturing method thereof, which can make an electrode terminal difficult to peel off for a long period of time and can stabilize the connection reliability between a conductive particle and an electrode terminal for a long period of time.

[0011]

The invention according to claim 1 is
The first electrode terminal formed on the first wiring board and the second electrode terminal formed on the second wiring board are arranged to face each other, and the first electrode terminal and the second electrode terminal are arranged. UV with electrode terminals
The UV light transmissive conductive member is adhered by a dispersed UV photo-curable adhesive, and the first electrode terminal and the second electrode terminal are dispersed in the UV light transmissive conductive member. It is characterized by being electrically connected by a conductive member.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the UV light transmissive conductive member is fine particles. The invention according to claim 3 is the same as the invention according to claims 1 and 2, wherein the UV
The light-transmitting conductive member is characterized by being made of a metal oxide having transparent conductivity.

The invention according to claim 4 is the same as claim 1 or claim 2.
In the invention described above, the UV light transmissive conductive member is made of an organic material having transparent conductivity. The invention according to claim 5 is the first wiring board,
Forming an uncured first UV photo-curable adhesive in which the UV light-transmissive conductive member is selectively dispersed only on the electrode terminals of, and then the uncured first UV photo-curable adhesive The step of irradiating the adhesive with UV light to cure the adhesive and adhering it to the first electrode terminal, and then the first UV light adhered onto the first electrode terminal of the first wiring board. The curable adhesive is brought into contact with the second electrode terminal of the second wiring substrate coated with the uncured second UV light curable adhesive, and UV light is applied to the uncured UV light curable adhesive. It is characterized by including a step of adhering the first wiring board and the second wiring board by irradiation and curing.

[0014]

According to the first aspect of the present invention, the UV in which the first electrode terminal on the first wiring board and the second electrode terminal on the second wiring board are dispersed in the UV photocurable adhesive agent. It is configured to be electrically connected by a light-transmissive conductive member. Therefore, when the UV light is irradiated, the UV light transmissive conductive member dispersed in the UV light curable adhesive can transmit the UV light. , All the UV photo-curable adhesive between the second electrode terminals can be firmly cured, and the UV light-transmissive conductive member and the first and second electrode terminals are firmly adhered by the UV photo-curable adhesive. Can be made. Moreover, the elasticity of the UV light curable adhesive itself can prevent the substrate and the electrode terminals from being damaged during pressure connection. Therefore, even if thermal stress or mechanical stress is applied, it is possible to prevent the conductive particles and the electrode terminals from peeling off for a long period of time, and it is possible to prevent defective resistance values from occurring. Can be stabilized over a long period of time.

According to a second aspect of the present invention, in the above-mentioned first aspect of the invention, since the UV light transmissive conductive member is composed of fine particles, the UV light that passes through the UV light transmissive conductive member.
It is possible to efficiently suppress light attenuation. Therefore, U
It is possible to shorten the curing time of the V-light curable adhesive, to completely cure the UV-curable adhesive, and to increase the number of points and areas in contact with the electrode terminals. Therefore, a low resistance and stable connection structure can be obtained.

According to a third aspect of the invention, the first and second aspects are
In the invention of 2, the UV light transmissive conductive member is made of a metal oxide having transparent conductivity, so that the conductive member is an inorganic substance, so that the volume resistivity can be lowered and a low connection resistance value can be efficiently obtained. be able to. According to a fourth aspect of the present invention, in the first and second aspects of the invention, since the UV light transmissive conductive member is made of an organic material having transparent conductivity, the conductive member is an organic material. The elasticity can effectively reduce damage to the substrate and the electrode terminals during pressurization, and stable electrical connection can be obtained.

According to a fifth aspect of the present invention, the uncured first UV light curable adhesive in which the UV light transparent conductive member is selectively dispersed only on the first electrode terminals of the first wiring board. And then irradiating the uncured first UV light-curable adhesive with UV light to cure the first UV light-curable adhesive and bond it to the first electrode terminal. Contacting the first UV photo-curable adhesive adhered on the electrode terminal with the second electrode terminal of the second wiring board coated with the uncured second UV photo-curable adhesive, UV to the uncured UV photocurable adhesive
The first wiring board and the second wiring board are bonded to each other by irradiating light and curing. Therefore, in addition to being able to obtain the effect of the invention described in claim 1, an uncured UV light curable adhesive in which the UV light transmissive conductive member is dispersed is simply applied to the electrode terminals in a short time. can do.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a view showing an electrode structure of an electric circuit board according to Embodiment 1 of the present invention and an enlarged portion of an electrode terminal.
FIG. 2 is a diagram showing a structure in which electric circuit boards are connected according to the second embodiment of the present invention and an enlarged portion of the connection structure. 1 (b) shows the enlarged portion X of FIG. 1 (a), and FIG. 2 (b) shows the enlarged portion Y of FIG. 2 (a). In the present embodiment, as shown in FIGS. 1 and 2, the electrode terminal 2 formed on the electric circuit board 1 and the electrode terminal 4 formed on the electric circuit board 3 are arranged so as to face each other. 4 is bonded with a UV light curable adhesive 6 in which a UV light transparent conductive member 5 is dispersed, and the electrode terminal 2 and the electrode terminal 4 are dispersed in the UV light curable adhesive 6 The electrical circuit board 1 and the electrical circuit board 3 are electrically connected to each other by means of 5, and the insulating UV photo-curable adhesive 7 is used to bond them.

Next, FIG. 3 is a diagram showing a method of connecting electric circuit boards according to the first embodiment of the present invention. First, FIG.
As shown in FIG. 3A, a UV photocurable adhesive 6 in which a UV light transmissive conductive member 5 made of transparent conductive fine particles is dispersed is evenly applied on a flat substrate 11, and then shown in FIG. As described above, the electric circuit board 1 is attached to the flat board 11 so that the electrode terminals 2 are on the side of the UV light curable adhesive 6.

Next, as shown in FIG. 3C, after peeling the electric circuit board 1 from the flat substrate 11 and transferring the UV photocurable adhesive 6 only onto the electrode terminals 2 of the electric circuit board 1, ,
As shown in FIG. 3D, the UV photocurable adhesive 6 of the electrode terminal 2 is irradiated with UV light to cure the UV photocurable adhesive 6 and the UV photocurable adhesive 6 is applied to the electrode terminal 2. Glue.

Then, an insulating UV light curable adhesive 7 is applied onto the electric circuit board 3 (or the electric circuit board with conductive particles or the like) on which the transparent electrode terminals 4 facing the electric circuit board 1 are formed. After that, the electrode terminals 2 of the electric circuit board 1 and the electrode terminals 4 of the electric circuit board 3 are aligned so that they are aligned with each other, and pressure is applied from the back surface of the electric circuit board 1 so that the U
The V photo-curable adhesive 6 and the electrode terminal 4 are brought into contact with each other, and the insulating UV photo-curable adhesive 7 is applied to the insulating UV photo-curable adhesive 7 from the rear surface of the transparent electric circuit board 3 by U.
By irradiating V light and curing it to bond the electric circuit board 1 and the electric circuit board 3 to each other, a wiring structure as shown in FIG. 3E can be obtained. At this time, since the UV light curable adhesive 6 on the electrode terminal 2 portion of the electric circuit board 1 has already been cured, the insulating U applied to the upper portion of the electrode terminal 4 at the time of pressurization.
The V photo-curable adhesive 7 is pushed away and is in contact with the electrode terminals 4 of the transparent electric circuit board 3.

In this embodiment, metal oxide can be used as the UV light transmissive conductive member 5 made of transparent conductive fine particles, for example, ITO, In2O3, SnO.
2, SnO2 (Pb), SnO2 (F), ZnO, Zn
O (In), ZnO (Al), ZnO (Si), CdI
A metal oxide such as n2O4, Cd2SnO4 or Cd2SnO4 can be used. Further, as the UV light transmissive conductive member 5 made of transparent conductive fine particles, an organic substance can be used, and for example, polyisothianaphthene or the like can be used. In addition, the UV light curable adhesive 6 and the insulating U
As the adhesive base material of the V light curable adhesive 7, polyacrylate, epoxy acrylate, urethane acrylate,
Adhesives such as polyester acrylate, polyether acrylate, melamine acrylate, and silicon acrylate can be used, and these are used for the electric circuit board 1.
It is preferable to select it appropriately according to the material of the transparent electrode terminal 4.

As described above, in this embodiment, the UV light transmissive conductive material in which the electrode terminals 2 on the electric circuit board 1 and the electrode terminals 4 on the electric circuit board 3 are dispersed in the UV light curable adhesive 6. The member 5 is configured to be electrically connected.
Therefore, when irradiated with UV light, the UV light curable adhesive 6
Since the UV light transmissive conductive member 5 dispersed therein can transmit UV light, all the UV light curable adhesive 6 between the conductive member and the electrode terminals, which could not be conventionally cured, is firmly cured. Therefore, the conductive member 5 and the electrode terminal 2 can be firmly adhered. Moreover, the elasticity of the UV light curable adhesive itself can prevent the substrate and the electrode terminals from being damaged during pressure connection. Therefore, even if a thermal stress or a mechanical stress is applied, the conductive particles 5 and the electrode terminals 2 are unlikely to be peeled off for a long period of time, and it is possible to prevent a defective resistance value from occurring. The connection reliability of can be stabilized over a long period of time.

Further, in this embodiment, since the UV light transmissive conductive member 5 is composed of fine particles, U which passes through the conductive member 5 is used.
The attenuation of V light can be efficiently suppressed. For this reason,
The curing time of the UV light curable adhesive 6 can be shortened, the UV curable adhesive 6 can be completely cured, and points and areas in contact with the electrode terminals 2 can be increased. Therefore, a low resistance and stable wiring structure can be obtained.

Further, in this embodiment, since the UV light transmissive conductive member 5 can be made of a metal oxide having a transparent conductivity, the conductive member 5 is an inorganic material, so that the volume resistivity can be lowered. It is possible to efficiently obtain a low connection resistance value. Further, in this embodiment, since the UV light transmissive conductive member 5 can be made of an organic material having transparent conductivity, since the conductive member 5 is an organic material, the elasticity of the conductive material 5 made of an organic material causes a substrate or Damage to the electrode terminals can be efficiently reduced, and stable electrical connection can be obtained. (Embodiment 2) The process of connecting the electric circuit board according to this embodiment is basically the same as that of the embodiment 1 of FIG. 3, and will be described with reference to FIG. First, as shown in FIG.
After applying a UV photo-curable adhesive 6 made of a modified epoxy acrylate-based adhesive in which a UV light-transmissive conductive member 5 made of ITO fine particles having an average particle diameter of 500 Å is dispersed to a thickness of 10 μm on a glass substrate 11, Figure 3 (b)
As shown in, TAB electric circuit board 1 for liquid crystal driver
The electrode terminal 2 portion of is bonded to the electrode terminal 2 of the flat substrate 11.

Next, as shown in FIG. 3C, the TAB electric circuit board 1 is peeled off from the glass substrate 11 and the UV light curable adhesive 6 is transferred only onto the electrode terminals 2 of the electric circuit board 1. After that, as shown in FIG. 3D, UV on the electrode terminal 2
The photo-curable adhesive 6 is irradiated with UV light to be cured and the UV-curable adhesive 6 is adhered onto the electrode terminals 2. And IT
1-PET on which transparent electrode terminal 4 made of O is formed
After the insulating UV photocurable adhesive 7 made of a modified epoxy acrylate adhesive is applied to the transparent electric circuit board 3 made of a film to a thickness of 15 μm, the electric circuit board 1 is arranged so that the electrode terminals 2 and the electrode terminals 4 are aligned. And the electric circuit board 3 are aligned with each other, and the electric circuit board 1 is pressed from the rear surface of the electric circuit board 1 so that the UV photo-curable adhesive 6 of the electrode terminal 2 is brought into contact with the electrode terminal 4, and the rear surface of the electric circuit board 3 By irradiating the insulating UV light curable adhesive 7 with UV light to cure the adhesive, the electric circuit board 1 and the electric circuit board 3 are adhered to each other.
The wiring structure as shown in (e) can be obtained. At this time, in the connection portion between the TAB electric circuit board 1 and the transparent electric circuit board 3, the conductive adhesive portion and the insulating adhesive portion are filled in the electrode portion and the gap portion, respectively, as in the case of the first embodiment. I was able to get the status. (Embodiment 3) The electric circuit board connection process according to this embodiment is basically the same as that of Embodiment 1 shown in FIG.
Will be explained. First, as shown in FIG. 3 (a), a UV light curable adhesive made of a modified urethane acrylate adhesive in which a UV light transmissive conductive member 5 made of SnO 2 (Pb) fine particles having an average particle diameter of 100 Å is dispersed. After applying 6 to the glass substrate 11 to a thickness of 10 μm, the electrode terminal 2 part of the electric circuit substrate 1 made of the TAB for liquid crystal driver is bonded to the flat substrate 11 by the UV light curable adhesive as shown in FIG. 3B. Stick on Agent 6.

Next, as shown in FIG. 3C, the TAB electric circuit board 1 is peeled off from the glass substrate 11 to remove the electrode terminals 2.
After transferring the UV light curable adhesive 6 only on the top, FIG.
As shown in (d), the UV light curable adhesive 6 on the electrode terminal 2 is irradiated with UV light to be cured, and the UV light curable adhesive 6 is adhered on the electrode terminal 2. Then, the transparent UV-curable adhesive 7 made of modified urethane acrylate adhesive is applied to the transparent electrode 4 made of ITO formed on the transparent electric circuit board 3 made of the composite-coated PES film to a thickness of 15 μm. After that, the electric circuit board 1 and the electric circuit board 3 are aligned so that the electrode terminal 2 and the electrode terminal 4 are aligned, and the electric circuit board 1 is pressed from the rear surface of the electric circuit board 1 to emit UV light on the electrode terminal 2. The curable adhesive 6 is brought into contact with the electrode terminals 4, and the insulating UV photo-curable adhesive 7 is irradiated with UV light from the back surface of the electric circuit board 3 to be cured to bond the electric circuit board 1 and the electric circuit board 3 together. By doing so, FIG. 3 (e)
A wiring structure as shown in can be obtained. Also in this example, a good connection state could be obtained as in Examples 1 and 2.

[0028]

According to the present invention, the UV adhesive between the conductive particles and the electrode terminals can be hardened to firmly bond the conductive particles and the electrode terminals, and even if thermal stress and mechanical stress are applied. There is an effect that the conductive particles and the electrode terminals can be made difficult to separate for a long period of time, and the connection reliability between the conductive particles and the electrode terminals can be stabilized for a long period of time.

[Brief description of drawings]

FIG. 1 is a diagram showing an electrode structure of an electric circuit board and an enlarged portion of an electrode terminal according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure in which electric circuit boards are connected according to the first embodiment of the present invention and an enlarged portion of the connection structure.

FIG. 3 is a diagram showing a method of connecting electric circuit boards according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a conventional method of connecting electric circuit boards.

FIG. 5 is a diagram showing a conventional method for connecting electric circuit boards.

FIG. 6 is a diagram showing a problem of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric circuit board 2 Electrode terminal 3 Electric circuit board 4 Electrode terminal 5 UV light transmissive conductive member 6 UV light curable adhesive 7 Insulating UV light curable adhesive 11 Flat substrate

Claims (5)

[Claims] 1. A first electrode terminal formed on a first wiring board and a second electrode terminal formed on a second wiring board are arranged so as to face each other, and the first electrode terminal is arranged. And the second electrode terminal are adhered to each other with a UV photo-curable adhesive in which a UV light-transmissive conductive member is dispersed, and the first electrode terminal and the second electrode terminal are connected to the UV light-transmissive conductive member. The U dispersed in
A wiring structure characterized by being electrically connected by a V light transmissive conductive member. 2. The wiring structure according to claim 1, wherein the UV light transmissive conductive member is fine particles. 3. The UV transparent conductive member is made of a metal oxide having transparent conductivity.
2. The wiring structure described in 2. 4. The UV transparent conductive member is made of an organic material having transparent conductivity.
The wiring structure shown. 5. A step of forming an uncured first UV light curable adhesive in which a UV light transparent conductive member is selectively dispersed only on the first electrode terminal of the first wiring board, Next, a step of irradiating the uncured first UV light curable adhesive with UV light to cure it and adhering it to the first electrode terminal, and then,
A second wiring board to which the uncured second UV photocurable adhesive is applied, on which the first UV photocurable adhesive adhered onto the first electrode terminal of the first wiring board is applied. A step of adhering the first wiring board and the second wiring board by contacting the second electrode terminals of the above and irradiating the uncured UV photocurable adhesive with UV light to cure the adhesive. And a wiring structure manufacturing method.