JPH0738241A - Electrode structure for printed wiring board and formation thereof - Google Patents

Abstract

PURPOSE:To provide means having high reliability and a low cost as a connecting electrode of a printed wiring board of the type to be electrically connected by contact. CONSTITUTION:Conductive particles 6 are disposed in a connecting part having a connecting electrode 11 coated with adhesive 5, so supported as to partly expose the particles 6 from a surface of the adhesive 5, and a printed wiring board 1 having the electrode 11 is effectively connected to an LCD board 2 having a connecting electrode 21 through a zebra connector 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure for a printed wiring board and a method for forming the printed wiring board and another printed wiring board or an electronic component by bringing them into electrical contact with each other.

[0002]

2. Description of the Related Art As a means for connecting a conventional printed wiring board 1 and a glass substrate (hereinafter referred to as an LCD substrate) 2 of an LCD by contact, a method shown in FIGS. 13 and 14 is generally adopted.

That is, the printed wiring board 1 is shown in FIG.
Connection electrodes 11 for connecting to the LCD substrate 2 as shown in (a) are formed.
As shown in (b), a connection electrode 21 corresponding to the connection electrode 11 is formed. Connection electrode 11 of printed wiring board 1
And the connection electrode 21 of the LCD substrate 2 are opposed to each other so as to overlap each other, and an anisotropic conductive rubber connector generally called a zebra connector 3 is interposed therebetween.

Then, as shown in FIG. 14, by sandwiching the printed wiring board 1 and the LCD substrate 2 from the outside by a bracket 4, the connection electrodes 1 of the printed wiring board 1 are connected.
1 and the connecting electrode 21 of the LCD substrate 2 are connected to the zebra connector 3
Is held in a conductive state via.

When the connection is made by such means, the zebra connector 3 and the connection electrode 11 of the printed wiring board 1 are only in contact with each other, and therefore the Cu foil which is the connection electrode 11 of the printed wiring board 1 is in contact. Is susceptible to oxidative corrosion and its reliability is reduced. Therefore, the Cu foil of the connection electrode 11 is subjected to surface treatment 11a by Au plating or the like.

In this case, in the surface treatment by Au plating or the like, the printed wiring board 1 is very expensive because the Au plating 11a and the like are applied even to unnecessary portions other than the connection electrodes 11 of the printed wiring board 1. Has become.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a connection electrode for a printed wiring board of the type which is electrically connected by contact.
It is an object of the present invention to provide an electrode connection structure and method for a printed wiring board which is highly reliable and can be obtained at low cost.

[0008]

In order to achieve the above object, the present invention provides a connection electrode for electrically connecting a first printed wiring board and a second printed wiring board or electronic parts by contacting each other. In, the conductive particles are arranged at the connection electrode coated with the adhesive or the joint portion including the connection electrode, and the conductive particles are fixed so that at least a part of the conductive particles is exposed from the surface of the adhesive. It is what

The present invention provides a method for forming an electrode of a printed wiring board, in which the first printed wiring board and the second printed wiring board or electronic parts are brought into contact to electrically connect to each other. An adhesive is applied to a joint portion including a connection electrode, and thereafter, conductive particles are arranged, and the adhesive is cured while the conductive particles are pressed onto the connection electrode. is there.

[0010]

According to the structure of the present invention, the conductive particles are arranged at the connection electrode or the joint portion including the connection electrode coated with the adhesive, and at least a part of the conductive particles is exposed from the surface of the adhesive. The conductive particles placed on the fixed connection electrodes of the printed wiring board enable protection and electrical connection of the connection electrodes, and the zebra connector is interposed between the connection electrodes of other printed wiring boards. When contacting with each other, the conventional A
Highly reliable conduction can be achieved at low cost as compared with the means using u plating.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a first embodiment relating to an electrode connection structure for a printed wiring board according to the present invention. In the first embodiment, the connection electrodes 11 are formed on the surface of the printed wiring board 1 at regular intervals as in the conventional case, and the connection electrodes 11 are connected to the connection electrodes 21 formed on the LCD substrate 2. It is the same as the conventional one in that it comes into contact with the bracket 4 via the zebra connector 3.

In the present invention, the conductive particles 6 and the conductive particles 6 are formed on the surface of the joint portion A of the printed wiring board 1 including the connection electrode 11 which faces the connection electrode 21 on the LCD substrate 2 side by the zebra connector 3. The adhesive 5 for fixing the permeable particles 6 is located. The conductive particles 6 are made of a conductive material such as Au or Pd, and the coating thickness of the adhesive and the size of the conductive particles 6 are selected so that a part of the conductive particles 6 is exposed from the surface of the adhesive 5. The conductive particles 6 are held by the adhesive 5 so as to come into contact with the connection electrodes 11.

As shown in FIG. 1A, the conductive particles 6 held on the connection electrodes 11 by the adhesive 5 are connected to the LCD substrate 2 side via the zebra connector 3 as shown in FIG. 1B. Contact the connection electrode 21 of. Therefore, it is possible to obtain an inexpensive and highly reliable conductive structure by the conductive particles 6 without performing Au plating 11a on the connection electrode 11 as in the conventional case. In this conductive structure, when the printed wiring board 1 may be exposed to a high temperature atmosphere by a soldering process or the like, a thermosetting adhesive or a UV curing adhesive is used as the adhesive 5. The adhesive reliably supports the conductive particles on the connection electrode 11.

Next, a manufacturing process for obtaining the conductive structure will be described with reference to FIGS. 2 (a), 2 (b) and 2 (c). First, in the joint portion A of the printed wiring board 1 including the connection electrode 11,
The adhesive 5 is applied by a dispenser or the like (Fig. 2
(A)). At this time, the thickness of the adhesive 5 applied is smaller than the diameter of the conductive particles 6.

Next, as shown in FIG. 2B, the conductive particles 6 are sprinkled and arranged on the adhesive 5 applied to the joint portion A. At this time, the conductive particles 6 are arranged so as not to contact each other. Then, the conductive particles 6 scattered and arranged on the adhesive 5 are pressed against the pressing jig 7 from above toward the connection electrode 11 side, and the adhesive 6 is cured in this state, whereby the conductive particles 6 are connected. It is fixed by the adhesive 6 while being in contact with the electrode 11.

When a thermosetting adhesive is used as the adhesive 5, heating of the pressing jig 7, heating from the printed wiring board 1 side, heating with warm air, heating with light, or the above heating means. The heat-curable adhesive can be cured by the combined heating. When a UV curing type adhesive is used as the adhesive 5, UV irradiation is performed from the side surface of the pressure jig 7, or the pressure jig 7 is formed of a transparent material and added. UV by irradiating UV from the pressure jig 7 side, or by using both in combination
The curable adhesive can be cured.

According to the above method, the first aspect of the present invention
The electrode structure of the printed wiring board shown in the embodiment can be formed. The conductive particles used in the present invention include Au.
Alternatively, in addition to Pd conductive particles, conductive particles as shown in FIGS. 3 to 5 can be used.

FIG. 3 shows another embodiment relating to the conductive particles used in the present invention. The conductive particles 6A according to this embodiment are two layers of a core particle 61 made of a base metal such as Ni and a surface layer 62 that forms a thin layer on the surface of the core particle 61 by plating or the like made of Au or Pd. Composed of structure. Also in this embodiment, the same operational effect as in the case of the conductive particles made of Au or Pd can be obtained.

FIG. 4 shows another different embodiment of the conductive particles used in the present invention. The conductive particle 6B according to this embodiment has a two-layer structure including a core particle 63 made of a resin and a surface layer 62 that forms a thin layer on the surface of the core particle 63 by plating or the like made of Au or Pd. Become. Also in this embodiment, the same operational effect as in the case of the conductive particles made of Au or Pd can be obtained.

FIG. 5 shows another different embodiment of the conductive particles used in the present invention. The conductive particles 6C according to this embodiment include a core particle 64 made of ceramics,
It has a two-layer structure of a surface layer 62 which forms a thin layer on the surface of the core particle 64 by means of plating such as Au or Pd. Also in this embodiment, the Au or Pd is used.
It is possible to obtain the same operational effect as in the case of the conductive particles made of.

In the first embodiment of the present invention, the conductive particles 6 have been described as being sprayed on all parts of the adhesive 5 applied to the joint A, but in the second embodiment shown in FIG. The conductive particles 6 are the connection electrodes 1 of the printed wiring board 1.
The case where the elements are selectively arranged is shown only on the upper part. By disposing the conductive particles 6 only on the connection electrodes 11, even when the pitch of the connection electrodes 11 is fine, a short circuit can occur between the adjacent connection electrodes 11 via the conductive particles. The reliability as a connection electrode is improved.

In this case, the conductive particles 6 on the connection electrode 11 may be in contact with each other, and even if the diameter of the conductive particles 6 is increased, there is no risk of short circuit.
Even if the coating thickness of the adhesive 5 varies, the conductive particles 6 are not completely buried in the adhesive 5, and the contact area is increased, so that the reliability is improved.

Next, FIGS. 7 (a), (b), (c),
A manufacturing process for obtaining the structure of the second embodiment will be described with reference to FIG. First, the connection electrode 11 of the printed wiring board 1
The adhesive 5 is applied to the joint portion A including the adhesive by a dispenser or the like (FIG. 7A). At this time, the thickness of the adhesive 5 applied is smaller than the diameter of the conductive particles 6.

Next, the arrangement jig 8 for conductive particles has a shape corresponding to the arrangement of the connection electrodes. When the conductive particles 6 are supplied onto the arrangement jig 8, the conductive particles 6 are connected. It is located on the array jig 8 corresponding to the arrangement of the electrodes (see FIG. 7).
Therefore, by transferring the conductive particles 6 to the transfer jig 9 as shown in FIG. 7C, the conductive particles 6 of the transfer jig 9 are transferred and transferred onto the connection electrode 11 as shown in FIG. , The conductive particles 6 can be located only on the connection electrode 11 (FIG. 7D).

FIGS. 8 to 12 show specific examples of the case where an array jig, a transfer jig, and a mask are used to array the conductive particles at the positions corresponding to the connection electrodes of the printed wiring board. . In the specific example of FIG. 8, the arrangement jig 8 for arranging the conductive particles 6 has a connection electrode 11 on its surface.
The concave portion 81 is formed in a portion corresponding to the position of the concave portion 81. Therefore, after the conductive particles 6 are scattered on the arrangement jig 8, the conductive jig 6 is tilted by a means such as tilting the conductive jig 6 other than the concave portion 81. The particles 6 are removed. As a result, the conductive particles 6 corresponding to the connection electrodes 11 remain on the array jig 8.

The conductive particles 6 remaining on the array jig 8
Is transferred onto the connection electrode 11 of the printed wiring board 1 by the same means as the transfer jig 9 of FIG. 7C, whereby the conductive particles 6 can be positioned only on the connection electrode 11.

In the specific example of FIG. 9, the entire conductive particles 6 or the core particles 61 are made of a magnetic material, and the array jig 8 is provided with a position corresponding to the connection electrode 11 from the S pole or the N pole. The magnetized portion 82 is formed. With this configuration,
When the conductive particles 6 are moved onto the arrangement jig 8, the conductive particles 6 can be located only in the magnetized portion 82. The conductive particles 6 remaining on the array jig 8 are connected to the connection electrodes 11 of the printed wiring board 1 by the same means as the transfer jig 9 of FIG. 7C.
The transfer to the upper side allows the conductive particles 6 to be positioned only on the connection electrode 11.

Further, FIG. 10 shows a specific example for arranging the conductive particles by using a transfer jig having a magnetized portion. In this case, all of the conductive particles 6 are made of a magnetic material or the core particles 61 of the conductive particles are made of a magnetic material, and the conductive particles 6 are scattered on the front surface of the arrangement jig 8 (FIG. 1).
0 (a)). Then, as shown in FIG. 10B, a magnetized portion 91 magnetized so as to correspond to the arrangement of the connection electrodes 11.
When the transfer jig 9 having the above is used and the transfer jig 9 is pressed against the array jig 8, the magnetized portion 91 of the transfer jig 9 is
The conductive particles 6 on the array jig 8 are transferred. By transferring the conductive particles 6 located on the magnetized portion 91 onto the connection electrode 11 of the printed wiring board 1, the conductive particles 6 can be located only on the connection electrode 11.

FIG. 11 shows a specific example for arranging conductive particles by using a mask having through holes. In this specific example, a mask 10 having through holes 10a formed at positions corresponding to connection electrodes of a printed wiring board is used. Joint A including connection electrode 11 of printed wiring board 1
Then, after applying the adhesive 5, the positions of the through holes 10a formed in the mask 10 are matched with the positions of the connecting electrodes 11, and the conductive particles 6 are provided on the connecting electrodes 11 from above the mask 10 through the through holes 10a. Can be supplied to. 20 is a mask 10
Is a squeegee for supplying the conductive particles 6 located on the upper side of the above to the connection electrode 11 through the through hole 10a. In the drawing, the mask 10 is arranged directly on the connection electrode 11 of the printed wiring board 1, but a mask is arranged on the arrangement jig 8 and conductive particles are arranged on the arrangement jig, It is also possible to transfer to the connection electrode 11 of the printed wiring board 1.

As a third embodiment of the present invention, FIG. 12 shows a case where the adhesive 5 is applied only on the connection electrodes 11 of the printed wiring board 1 and the conductive particles 6 are arranged thereon.
In this embodiment, since the adhesive 5 is applied only on the connection electrodes 11 of the printed wiring board 1, even if the conductive particles 6 are sprinkled all over the connection portion A, the conductive particles 6 are not sticky. It will be arranged only on the part where the certain adhesive 5 is applied. In order to form the conductive particles 6 on the connection electrodes 11 of the printed wiring board 1, the arrangement means as shown in FIGS. 8 to 11 can be used.

[0031]

According to the structure of the present invention, even if the surface of the connecting electrode is not subjected to expensive Au plating as in the prior art, the conductive particles held by the adhesive can be used to conduct electricity by contact with the zebra connector. Be reliable,
Moreover, it has an effect that can be achieved at low cost, and when the conductive particles are arranged only on the connection electrodes, even if the pitch of the connection electrodes becomes small, there is no fear of short-circuiting, and the conductive particles can be provided to the connection electrodes. Since the size can be increased, the contact area can be increased and the reliability is improved.

[Brief description of drawings]

FIG. 1 shows a first embodiment relating to an electrode connection structure of a printed wiring board according to the present invention, (a) is a schematic sectional view of an electrode structure of a printed wiring board to be connected, and (b) is (a) FIG. 3 is a schematic cross-sectional view showing a connection structure between the electrode structure of the printed wiring board and the electrode structure of the LCD substrate of FIG.

2A and 2B are views for explaining a manufacturing process according to the first embodiment of the present invention shown in FIG. 1, in which FIG.
(B) shows a conductive particle distributing step, and (c) shows a conductive particle pressing and adhesive curing step.

FIG. 3 is a drawing showing an example of conductive particles used in the present invention.

FIG. 4 is a view showing another example of conductive particles used in the present invention.

FIG. 5 is a view showing another example of conductive particles used in the present invention.

FIG. 6 is a schematic sectional view showing a second embodiment relating to the electrode connection structure of the printed wiring board in the present invention.

FIG. 7 is a view for explaining the manufacturing process according to the second embodiment of the present invention shown in FIG. 6, where (a) is an adhesive applying step,
(B) is a conductive particle arranging step in the arranging jig, (c)
Shows a transfer process to a transfer jig, and (d) shows a transfer process onto a connection electrode of a printed wiring board.

FIG. 8 is a diagram for explaining a specific example for arranging conductive particles at a predetermined position on an arranging jig.

FIG. 9 is a drawing for explaining a specific example for arranging conductive particles at a predetermined position on an arranging jig.

FIG. 10 is a diagram showing a specific example for arranging conductive particles at a predetermined position by a transfer jig having a magnetized portion,
(A) is a state in which conductive particles having a magnetic material are dispersed on the array jig, and (b) is a state in which the conductive particles on the array jig are moved to a transfer jig having a magnetized portion formed at a predetermined position. The respective states are shown.

FIG. 11 is a view showing a specific example for arranging conductive particles with a mask having through holes.

FIG. 12 is a schematic sectional view showing a third embodiment relating to the electrode connection structure of the printed wiring board in the present invention.

FIG. 13 shows an electrode structure used for an electrode connection structure,
(A) is a printed wiring board, (b) is an LCD substrate.

FIG. 14 is a schematic cross-sectional view of a conventional contact type electrode connection structure for a printed wiring board.

[Explanation of symbols]

 A joint part 1 printed wiring board 11 connection electrode 2 LCD substrate 21 connection electrode 3 zebra connector 4 bracket 5 adhesive 6 conductive particles 7 pressure jig 8 array jig 9 transfer jig

Claims (3)

[Claims] 1. A connection electrode for connecting a first printed wiring board and a second printed wiring board or an electronic component to make an electrical connection, and a connection electrode coated with an adhesive or a joint portion including the connection electrode. An electrode structure of a printed wiring board, characterized in that conductive particles are arranged on the surface of the adhesive, and the conductive particles are fixed so that at least a part of the surface of the adhesive is exposed. 2. The electrode structure of a printed wiring board according to claim 1, wherein the coating thickness of the adhesive is smaller than the diameter of the conductive particles. 3. An adhesive agent is applied to a connection electrode or a joint portion including the connection electrode in a connection electrode for electrically connecting by contacting the first printed wiring board and the second printed wiring board or an electronic component. Then, after that, conductive particles are arranged, and the adhesive is cured in a state in which the conductive particles are pressed onto the connection electrode, and the method for forming an electrode of a printed wiring board.