JPH0736348B2 - Low pitch heat seal connector and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pitch heat seal connector used for connecting electric and electronic parts to each other and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional heat seal connector has a wiring pattern formed on an insulating base material, usually an insulating flexible base material, by a method such as printing or etching, and then insulating
An anisotropic conductive adhesive layer in which conductive particles are randomly dispersed and mixed in the adhesive, or a connection terminal electrode of the circuit board to be exposed exposed from the insulating adhesive layer formed at the connection part during heat sealing in order to obtain electrical conduction between, it was something like that contains conductive particles for connection in the wiring <br/> pattern. However, with the recent miniaturization and refinement of electric and electronic devices, the pitch of conductive lines in a wiring pattern has become finer, and the connection pitch is required to be as low as 0.05 to 0.4 mm pitch. Came. Along with this
There, narrow the pitch conductive particles between the wiring pattern is present, it is difficult to maintain insulation between the conductive lines, reducing the number of conductive particles as a countermeasure, increasing the connection resistance
Big deal In addition, the wiring pattern can be
When the over down to try to screen printing, generate screen clogging by the conductive particles, which since the cause of disconnection of the wiring pattern, it is necessary to increase the mesh of the screen, as a result of the low pitch the amount of the paste is increased to pass through the screen in the printing, who printed line widths than the screen of the setting line width increases, the so-called "sagging" because of easy Ri to put a leak occurs, and particularly 0.05 In the production of a low-pitch heat seal connector having a pitch of up to 0.4 mm, there were problems that the yield was very poor and that line formation was not possible at all.

[0003]

Therefore, the object of the present invention is to provide a low pitch conductor such as 0.05 to 0.4 mm.
The present invention provides a heat-seal connector having a high reliability and a low connection resistance with respect to a poor electrical connection such as a poor electrical insulation or a disconnection even when the electrical line is provided, and a method for manufacturing the same.

[0004]

The inventor has found that the cause of the sagging phenomenon of the conductive paste, which has made it difficult to form a wiring pattern at a low pitch in screen printing, is
As a result of conducting research on the assumption that the conductive paste spreads easily when brought into contact with an insulating base material, the so-called wettability (affinity), the result is good wettability in the conductive line direction and leakage due to sagging. in order to not to, if poor wettability in the direction perpendicular to the conductive lines, such as shall be printed in a large screen mesh to the addition of conductive particles for connection to the conductive paste Even in such a case, they have found that a wiring pattern with a low pitch can be easily formed, and have reached the present invention.

That is, the first invention is one side or
Insulation with fine grooves and / or ridges on both sides
An edge substrate and a particle size of 5 to 100 μm on the insulating substrate
Conductive paste containing conductive particles in an amount of 0.1 to 50% by volume
Along the groove and / or ridge formed by
Wiring pattern having conductive lines with a pitch of 05 to 0.4 mm
And the wiring pattern to cover the wiring pattern
Insulation provided on the connection part with the circuit board to be connected
The present invention relates to a low-pitch heat-seal connector comprising a heat-adhesive adhesive layer, and the second invention is wiring on one side or both sides of an insulating base material, particularly an insulating flexible base material. Fine grooves and / or ridges are previously provided along the conductive lines of the wiring pattern at the place where the pattern is to be formed, and thereafter, conductive particles having a particle size of 5 to 100 μm are added.
Wiring pattern using conductive paste added 1 to 50% by volume
Screen-printing a core, and then providing an insulating heat-adhesive adhesive layer at a connection portion of the wiring pattern with at least a circuit board to be connected. It is a thing.

The details of the present invention will be described below with reference to the drawings. FIG. 1 shows a low-pitch heat-seal connector 1 of the present invention, which is connected to a circuit board to be connected.
Shows as one embodiment in, (a) figure is a plan view, (b) drawing enlarged partial longitudinal sectional view taken along the I-I arrow line in (a) FIG. In the figure, 4 is an insulating base material, 2 is this insulation
Conductive lines 3 formed by the conductive paste on the conductive substrate 4 are conductive particles added to the conductive paste for connection . 5 covers the conductive line 2 and is on the insulating substrate 4
Insulating thermal bonding adhesive layer provided on, 6 and 7 absolute
Ru ridges and Mizodea provided along the conductive lines 2 to 4 sides edges substrate. Incidentally, it is provided so as to expose, but some of the conductive particles 3 showed that are entirely covered with the conductive particles 3 5 insulating thermally bonding adhesive layer in (b) FIG. Good. FIG. 2 shows an enlarged partial vertical cross-sectional view of a different embodiment of the protrusion 6 or groove 7 formed on the surface of the insulating base material 4. FIG. 2A is an embodiment of the protrusion 6 having a substantially rectangular cross section, (B)
The figure shows an embodiment of the groove 7 having a substantially rectangular cross section, and the figures (c) and (d) show different embodiments when the ridge 6 and the groove 7 are combined. FIG. 3 is an enlarged partial vertical sectional view showing a state when the low pitch heat seal connector 1 of the present invention shown in FIG. 1 is connected to the connection terminal electrode 9 of the circuit board 8 to be connected.

The insulating base material 4 used in the present invention is mainly used for a printed wiring board (hereinafter referred to as a PCB) on which a liquid crystal display (LCD) and a driver IC are mounted or for signal transmission between PCBs. since, 10 ⁸ Ω · cm or more, and particularly also is preferred with ^{10 10 Ω} · cm or more insulating. Also, the insulating base material 4
Can be a rigid one or a flexible one, but in order to withstand various stresses and vibrations due to temperature change, humidity change, etc. at the heat seal part, external force due to drop, etc. The insulating base material is preferably flexible. Examples of materials that satisfy these conditions include polyester films such as polyethylene terephthalate (hereinafter referred to as PET), polyethylene naphthalate, and polybutylene terephthalate, polyimide films, phenolic paper, glass-epoxy films, and the like.

The ridge 6 formed on the surface of the insulating base material
And the width of the groove 7 is the pitch of the conductive lines in the wiring pattern.
If it is larger than 0.05 to 0.4 mm, it will prevent leakage.
Since it cannot be exhibited, it is desirable that the pitch is equal to or less than the pitch of the conductive lines , and particularly 1/10 or less of the pitch.
The closer the distance between the adjacent ridges 6 and the grooves 7 is, the better, but the upper limit is preferably equal to or less than the pitch of the conductive lines , and particularly preferably 1/10 or less of the pitch thereof. 7 is preferably continuous along the conductive line 2, but even if it is not continuous, it may be oriented in the same direction as the conductive line 2, and the degree of the angle of orientation with respect to the conductive line 2 ± 10 ° within, especially within ± 5 ° is good
Good In order to control the wetting of the conductive paste, the inclination angle of the side surface of the ridge 6 or the groove 7 is important, and it is preferable that the surface intersects the insulating base material 4 surface by 30 ° or more. preferable. However can not be sufficiently controlled height wetting of the conductive paste or too low or ridges 6 are too shallow depth of the groove 7, the depth Ah <br/> Rui groove 7 the height of protrusion 6 Is 0.1 μm or more, especially 1 μm
The above is preferable. The groove 7 is too deep insulating <br/> strength of the substrate 4 becomes weak, also the projection 6 is too high insulating
When the flexible base material 4 is flexible , its characteristics are impaired. Therefore, it is desirable that the depth or height is 1/2 or less of the thickness of the insulating base material 4.

[0009] projections 6 and grooves 7 While Ru is formed along the conductive lines of the wiring path <br/> turn to be formed later, as a method for forming the groove 7, it is processed along the conductive line by a laser beam method, a method to <br/> groove by transferring more insulating substrate 4 a convex wiring <br/> pattern formed on the mold or the roll to the press is illustrated. Examples of the method for forming the ridges 6 include a method in which a UV curable ink is applied to the surface of the insulating base material 4 with a predetermined thickness, UV exposure is performed with a desired wiring pattern, and then the uncured portion is removed. Further, according to a method of rubbing in a certain direction with sandpaper, a wire brush, a needle or the like, or a sandblasting method, the portion that has been dug out at the same time as the formation of the groove 7 remains as burrs and acts as the ridge 6. Gives good results for control of wetting.

As the conductive paste, carbon, gold, silver,
Copper, known conductivity imparting powder polyester resins such as nickel, polyurethane resins, epoxy resins, the binder is contained 40 to 95% by weight, the volume resistivity such as an acrylic resin is obtained by the following 10 ⁰ Ω · cm preferable. The electroconductivity-imparting powder used here exists in the binder in a floating state, imparts isotropic electroconductivity, and contributes to conduction in the longitudinal direction when a line is formed, and usually has a particle diameter of 0. It is preferably about 0.01 to 1 μm, and the shape is preferably scaly, fibrous or amorphous . On the other hand, absolute
As factors that determine the wettability of the conductive paste with respect to the edge base material, the viscosity of the conductive paste, the difference in SP value (solubility parameter) between the insulating base material and the conductive paste, the surface tension of the conductive paste, and the like are considered. Since the paste contains a large amount of the conductivity-imparting powder, it is almost controlled by the viscosity. To improve the wettability, the viscosity should be adjusted to 50 to 500 poises.

The conductive particles 3 for connection added to the above conductive paste include carbon particles, metal particles such as gold, silver, copper, platinum, palladium, nickel, tin and solder,
It is possible to use plastic particles whose surfaces are plated, and these are in the conductive lines 2 of the wiring pattern formed of a conductive paste , and are used as the connection terminal electrodes 9 of the connection circuit substrate 8. Since it is for electrically conducting the conductive line 2 of the wiring pattern on the insulating base material 4,
Since it is desirable that at least a part is exposed from the conductive line 2, the particle size is set to 5 μm or more, preferably the thickness of the conductive line or more, and when it is too large, the adhesive strength is lowered, so 100 μm or less, preferably 50 μm or less
To be done. Various shapes of conductive particles can be used, but to strengthen the holding force of the conductive paste.
It is preferable that the surface of the conductive particles has irregularities.
Similarly, it is also effective to treat the surface of the conductive particles with a coupling agent in order to increase the holding power. The amount of conductive particles added to the conductive paste is too small, the number of connection points is small and the stability of conduction is poor, and the reliability is poor.
It should be 0.1 to 50% by volume, especially 1 to 2
It is preferably 0% by volume. The wiring pattern is formed by screen printing, and the opening of the screen mesh is preferably a particle size or more, particularly 1.5 times the particle size or more in order to prevent clogging of the conductive particles 3 for connection. . If the mesh size is too large, it is difficult to make a low-pitch screen with an emulsion.
It is preferably not more than μm, particularly not more than 100 μm.

[0012] The adhesive used to form the insulating thermal bonding adhesive layer 5 which definitive connection portion between the connection circuit board, the degree of fluidity of the conductive particles 3 for connection when heat sealing is exposed When the conductive particles 3 for connection are formed so as to be exposed before heat sealing, it is only necessary that the particles have thermal adhesiveness, and are thermoplastic, thermosetting, or a blend thereof. It is arbitrarily selected from the products. As a specific example of the thermoplastic adhesive, a polyamide-based adhesive,
Polyester-based, ionomer-based, polyethylene-based copolymers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, various synthetic rubbers Examples thereof include those of the system, and modified products and composites thereof. Examples of thermosetting adhesives include epoxy resin-based, urethane-based, acrylic-based, silicone-based, chloroprene-based, nitrile-based synthetic rubbers, and mixtures thereof. These include curing agents, vulcanizing agents, control agents, deterioration inhibitors, heat resistance additives, thermal conductivity improvers, in any case,
A tackifier, a softening agent, a coloring agent, a metal deactivator, etc. may be added, but the content of impurity ions is preferably as small as possible from the viewpoint of improving reliability.

[0013]

According to the present invention, for connecting the wettability of the conductive paste as described above by poor in a direction perpendicular to the well conductive lines in the conductive line direction, in the conductive paste
Even when it is necessary to print on a screen having a large opening because it contains the conductive particles, it is possible to obtain a heat-seal connector with a low pitch and few defects due to leakage or disconnection of conductive lines.

[0014]

EXAMPLES Specific embodiments of the present invention will be described below with reference to Examples and Comparative Examples. Example One side of a PET film having a thickness of 25 μm was rubbed on one side with a jig in which needles made of stainless steel were arranged,
A groove having a depth of 0.2 to 2 μm and a ridge having a height of 0.2 to 2 μm were formed so that each pitch was about 10 μm. On the other hand, silver and carbon as a conductivity-imparting powder are mixed in a urethane-based binder to have a volume resistivity of 10 when dried.
^-4 Ω. the conductive paste 100 parts by volume with a cm, Ni particles plated with gold particle size 20 to 30 [mu] m (for connection
10 parts by volume of conductive particles) to increase the viscosity to 150 poise
Adjusted to. Next, a conductive line pitch of 0.2 mm and a line width of 0.1 m on a stainless steel mesh with an opening of 60 μm.
by using a screen plate of the wiring patterns created so that m, the wiring pattern screen printed onto the PET film by a conductive paste obtained by adding the above conductive particles
did. At this time, the conductive particles are exposed from the conductive line.
The thickness of the conductive line excluding this is 15 μm.
there were. A thermoplastic adhesive layer of styrene-ethylene-butylene-styrene block copolymer was provided on the entire surface by screen printing so as to have a thickness of 25 μm. The length of the conductive line is 40 mm and the number of lines is 24.
The low pitch heat seal connector was obtained by sizing so as to be zero.

Comparative Example A similar heat seal connector was produced by omitting only the step of providing grooves and ridges on the PET surface of the example. Evaluation: 10 heat seal connectors for each of the examples and comparative examples
Leak inspection and continuity inspection were performed on 0 sheets. In the examples, none leaked and none failed in conduction, whereas in the comparative example, 98 leaked and two non-leaked sheets were further inspected. However, disconnection was recognized on one sheet.

[0016]

According to the present invention, it is possible to easily obtain a heat-seal connector having a low pitch and having no fear of leakage or defective conduction, and the cost is reduced because the product yield is increased. In addition, it was considered difficult in the conventional screen printing,
0.05mm pitch, 0.1mm pitch conductive line
Since it is also possible to form, the use of the low-pitch heat seal connector of the present invention can further reduce the size and precision of electronic and electric devices.

[Brief description of drawings]

FIG. 1 shows a low pitch heat seal connector of the present invention ,
This is shown as an embodiment of a connecting portion with a circuit board to be connected , and (a) is a plan view, (b) is a plan view (I).
FIG. 4 is an enlarged partial vertical cross-sectional view taken along the line I of FIG.

FIG. 2 is an enlarged partial vertical cross-sectional view showing an embodiment of the insulating base material used in the low-pitch heat-seal connector of the present invention, in which grooves or ridges formed on the surface of the base material are different from each other. Is an embodiment of a ridge, (b) is an embodiment of a groove, and (c) and (d) are different embodiments when a ridge and a groove are combined.

FIG. 3 is an enlarged partial vertical cross-sectional view showing a state when the low-pitch heat seal connector of the present invention shown in FIG. 1 is connected to a circuit board to be connected.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Low pitch heat seal connector, 2 ... Conductive line, 3 ... Conductive particle, 4 ... Insulating base material, 5 ... Insulating heat-adhesive adhesive layer, 6 ... Ridge, 7 ... Groove, 8 ... Connected Circuit board, 9 ... Connection terminal electrode.

Claims (2)

[Claims] 1. Fine grooves and / or on one or both sides
Insulating base material provided with ridges and on this insulating base material
0.1 to 50 volume of conductive particles having a particle size of 5 to 100 μm
% Said groove formed by the conductive paste added and
/ Or 0.05-0.4mm pitch conductivity along the ridge
A wiring pattern with lines and the wiring pattern
Cover and insulate at least the connected circuit board on the insulating substrate.
It is composed of an insulating heat-adhesive adhesive layer provided on the connecting portion.
Low pitch heat seal connector characterized the door. To 2. A place to form one or both surfaces of the wiring patterns <br/> down of the insulating base, provided fine grooves and / or ridges along the conductive lines of the pre-wiring pattern, particle thereafter Conductive particles having a diameter of 5 to 100 μm are added in an amount of 0.1 to 50.
Use a conductive paste with volume% added to scan the wiring pattern.
A method for producing a low-pitch heat-seal connector, which comprises performing a clean printing and then providing an insulating heat-adhesive adhesive layer on a connection portion of the wiring pattern with at least a circuit board to be connected.