JPH0685344B2 - Method for manufacturing heat seal connector - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a liquid crystal display (LC
D), electroluminescence (EL), light emitting diode (LED), electrochromic display (ECD), plasma display (PDP), and the like, a circuit board on which the connecting terminals of the display body and its driving portion are mounted, or various electric circuits. The heat seal connector used for connecting between the boards.

[0002]

2. Description of the Related Art Conventionally, a heat seal connector is L
It is used for connecting a display device such as CD, EL, LED, ECD, PDP and the like to a hard printed wiring board (PCB) or a flexible printed circuit board (FPC), or a connection between PCB and FPC. 2. Description of the Related Art In recent years, the number of circuits on various electric circuit boards used for a heat seal connector has been increasing with the increase in size, color and fineness of a display, and one heat seal connector The number of lines contained in the circuit pattern is about 100 to 700. Conversely, the conductive line width of the circuit pattern is 0.07 to 0.15 mm and the pitch is 0.1.
Since it is 5 to 0.30 mm, it is becoming more difficult to form conductive lines by screen printing in the conventional method.

Conventionally, the manufacture of a heat seal connector has been
A method of forming conductive lines on an object to be printed by a screen printing method using a conductive paste prepared by mixing and dispersing fine conductive powder in an organic polymer binder solution is used. The conductive paste is printed through a desired screen pattern-shaped screen opening. Immediately after printing, the conductive paste is formed by a screen material having a wire diameter of about 10 to 40 μm and an intersection of the wire materials. The separated point-like pastes are then leveled and connected to each other in a short time to form a conductive line having a desired shape.

In such a screen printing method, the conductive paste also flows in the width direction of the conductive line, and usually tends to spread about 30 to 70 μm from the width of the screen opening. In order to obtain a high temperature, the device has been devised to increase the viscosity and thixotropy of the conductive paste and increase the viscosity immediately after printing to suppress the flow. In this method, basically, it was necessary to previously provide the screen opening with a width narrower than the width of the desired conductive line by at least 30 to 70 μm, but when the pitch is reduced to about 0.15 to 0.30 mm. The width of the screen opening corrected as described above is 0.
It becomes as narrow as 02 to 0.10 mm, and the ratio of division into the screen material with respect to the width of the screen opening is further increased, making it difficult to obtain a precise electrically conductive line. However, there were limits to the pitch and conductive line width that could be accommodated by screen printing.

[0005]

Therefore, according to the above printing method, it is substantially difficult to manufacture a heat seal connector having a pitch of 0.3 mm or less. As the conductive line becomes finer, the electrical connectivity of the conductive paste is impaired, and a fatal inconvenience occurs such as constriction of the conductive line, loss of conduction due to blurring or disconnection, and a screen. If the width of the opening is not corrected narrowly, the width between the conductive lines becomes narrower and the conductive lines between adjacent conductive lines may be misaligned when the heat seal connector is connected. There is a fatal inconvenience that a short circuit occurs and the function as a connector cannot be achieved.

Further, in the conventional method, since the range of printing conditions is narrow, there is the complexity of having to adjust the viscosity of the conductive paste and change the setting of printing conditions, and the manufacturing conditions are unstable. It often happens that the viscosity of the conductive paste and the printing conditions do not match.For example, if an excessive amount of conductive paste is supplied, the conductive line becomes thicker or bleeding or sagging occurs. However, the production efficiency is lowered, and desirable printing with a conductive line pitch of 0.30 mm or less is practically impossible.

Therefore, the object of the present invention is to solve the problems of the conventional screen.
The printing method could not be applied industrially, for example, 0.
10-0.20mm fine pitch pattern heat seat
To provide a connector. Another issue is
It is an object of the present invention to provide a method for easily and reliably manufacturing a heat seal connector having clear and fine conductive lines by eliminating the above-mentioned inconvenience.

[0008]

In order to overcome the above-mentioned problems, the present inventor has conducted earnest research on a method for industrially advantageously and stably forming a conductive fine pitch pattern by screen printing. As a result, we found that it is effective to properly control the temperature when printing conductive paste,
The present invention has been reached.

That is, according to the present invention, a plurality of conductive lines made of a conductive paste and having a width substantially half the conductive line pitch are formed on the insulating polymer film, and the insulating lines are formed on the surface of the conductive line group. In a heat seal connector in which a layer electrically connected to the electrode to be connected via the adhesive layer and conductive particles is formed, the heated conductive paste is passed through the screen opening, After passing, the sheet is cooled to form a conductive line having a pitch of 0.3 mm or less by setting the difference between the width of the conductive line and the width of the screen opening to be 10 μm or less to form a fine pitch pattern heat sheet. The present invention provides a method for manufacturing a connector.

The insulating polymer film used in the method of the present invention preferably has excellent heat resistance. Examples of such polymer materials include polyimide, polyethylene terephthalate, polybutylene terephthalate, Polycarbonate, polyphenylene sulfide, polyethylene naphthalate, poly 1,4-cyclohexane dimethylene terephthalate, polyarylate and liquid crystal polymer.
Etc. Also, they usually have a thickness of 10 to 50.
The film is selected from a film having a thickness of 10 .mu.m, but a thin film having a thickness of about 10 to 25 .mu.m is preferable because it is necessary to easily transfer the heat of the conductive paste, and it is necessary to instantly transfer the heat to the printing table kept at a low temperature. It is desirable that the surface in contact with the table is free from minute irregularities or distortions that may trap air.

The conductive paste is generally prepared by using an organic polymer binder and a conductive powder in a solvent to form a paste, and the conductive material is formed by removing the solvent. Examples of such organic polymer binders include vinyl chloride resin, vinyl acetate resin, copolymers thereof, acrylic resin, thermoplastic polyester, thermoplastic polyurethane, polybutadiene, polyimide resin, epoxy resin,
Examples include alkyd resins and phenolic resins. A curing agent such as isocyanates, amines and acid anhydrides can be used for these resins, if necessary.

Examples of the solvent for dissolving these binder resins include ester systems such as methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, butyl acetate and amyl acetate; methyl ethyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, Ketone systems such as methyl amyl ketone, ethyl amyl ketone, isobutyl ketone, methoxymethylpentanone, cyclohexanone, diacetone alcohol; methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, methoxybutyl acetate, methyl carbitol acetate, acetic acid Ether ester systems such as ethyl carbitol, acetic acid dibutyl carbitol; chlorinated hydrocarbon systems such as trichloroethane and trichloroethylene; n-butyl ether, diisoamyl ether, n Butylphenyl d - ether, propylene oxide, furfural - ether system - et like Le; isopropyl alcohol - le, isobutyl alcohol - le, Amiruaruko - Le, cyclohexanol - such as Le alcohol - Le system;
Examples include hydrocarbons such as benzene, toluene, xylene, isopropylbenzene, petroleum spirit, petroleum naphtha, and the like.

As these solvents, those which dissolve the binder resin to be used are selected and used, and ester type, ketone and ether ester type are preferably used. Further, in the present invention, it is required to increase the temperature difference before and after the screen printing. Therefore, from the viewpoint of stability of density and viscosity before printing, 180 ° C or higher, preferably 200 ° C or higher. The high-boiling point solvent is practically used advantageously.

The conductive powder dispersed in the binder resin is usually in the form of fine powder of about 0.1 to 50 μm, and the shape thereof is, for example, granular, scale-like, plate-like, spherical,
It may be dendritic, dice-shaped or the like. Also,
Examples of conductive materials include silver, silver-plated copper, copper, gold,
Examples thereof include nickel, palladium and alloys thereof, resin powder plated with these metals, carbon black such as furnace black and channel black, and graphite powder.

These may be used alone or in combination of two or more. These conductive powders are usually used in an amount of about 10 to 90% by weight based on the organic polymer binder, but an appropriate amount is selected and used depending on the type and particle size of the substance. If necessary, the conductive paste may further include a curing accelerator, a leveling agent, a dispersion stabilizer,
Defoaming agents, thixotropic agents, metal deactivators, etc. can be added.

Generally, the conductive paste exhibits a thixotropic flow in which the viscosity becomes lower as the shear stress becomes larger, but this thixotropy is determined by using an E-type viscometer especially by adding carbon black or dry silica. The shear rate measured at 2 sec ^-1 and the viscosity at 20 sec ^-1 are adjusted so as to be 2 to 15. In the present invention, in addition to the thixotropy, the viscosity due to the temperature difference is controlled, the conductive paste is reduced in viscosity to a suitable viscosity for screen printing before printing, and the viscosity is increased immediately after printing to increase the conductive paste. It is important to reduce the flow of strike.

The viscosity of the conductive paste is affected by the solution concentration and molecular weight of the organic polymer binder, the type of conductive powder, the blending amount, etc., but since it is necessary to increase the viscosity difference before and after printing, the viscosity immediately after printing The viscosity of the paste is 1 at a temperature of 0 to 25 ° C.
The porosity is preferably 000 poises or more, preferably 3000 poises or more, and in this case, it is suitable that the printing state is heated to 30 to 50 ° C. before printing and about 100 to 700 poises.

The method of forming the conductive lines is carried out by screen printing. The screen plate used for this is, for example, a metal frame having a side of 300 to 1000 mm and a stainless steel wire having a diameter of 10 to 40 μm. The iron alloy is plain-woven, twill-woven, gauze, nickel or the like is deposited in a grid pattern on an electroformed metal plate and covered with a mask material such as acrylic resin except for the openings through which the conductive paste passes. Used.

In order to form a fine conductive line, it is necessary to make the screen wire material thin so as not to block the opening. The screen opening ratio / screen thickness ratio is 0.8 or more. Is preferable, and 1.5 or more is more preferable. The aperture ratio is preferably 35% or more, more preferably 60% or more. Further, since the flow of the conductive paste is suppressed as much as possible, the width of the opening may be set to be equal to the width of the required conductive line or to be narrowed by about 10 μm.

A commercially available printer can be used, but since it is necessary to provide a temperature difference between the conductive paste before and after printing, that is, before and after the conductive paste passes through the screen opening, a heating and cooling mechanism is separately provided. It is necessary to provide. The method of the present invention will be described with reference to the example of the printing apparatus shown in FIG. 1 attached.
Is provided so that the entire surface of the frame is uniform, or in order to keep the temperature uniform, a soot of which temperature is controlled separately is circulated through the heat medium inlet / outlet 10 in the metal frame 13 having a hollow inside to form the metal frame. By heating and transferring heat from the metal frame to the metal mesh 4, the conductive paste 2 provided on the upper surface of the metal mesh is indirectly heated to 30 to 50 ° C. It is also preferable to heat the squeegee 7 and the paste return 8 for pushing the conductive paste 2 into the screen opening with a flat heater 6.
In addition, in the figure, 11 is an insulating polymer film which is an object to be printed, 3 is a screen closing portion, and 5 is a mask portion.

Further, heating the conductive paste temporarily stopped by the reciprocating squeegee and the paste return from the lower surface of the gauze with a flat-plate heater 6 is a conductive paste. -It is effective in heating the strike. However, since the metal frame and the gauze are generally fixed with an adhesive, it is preferable not to heat them to 80 ° C. or higher in order not to reduce the adhesive strength. Direct heating of the conductive paste with warm air accelerates the evaporation of the solvent of the conductive paste and should be avoided.Enclose the screen with a windshield to prevent air flow. Providing a cover 9 is desirable.

The cooling mechanism is such that the metal table 12 having a suction hole for fixing the film to be printed is made hollow, and the entrance 10
The temperature-controlled refrigerant is further passed through the inside to cool the substrate.
It can be maintained at a temperature of about 25 ° C. At this time, care must be taken because water drops will adhere if the temperature of the atmosphere is high.

It is not necessary to limit the adhesive of the heat seal connector applied to the present invention. If it is an insulating adhesive that exhibits adhesiveness by heating, it may be a thermoplastic resin or a thermosetting resin. It may be any of resins. Thermoplastics have the advantage of bonding at a relatively low temperature for a short period of time and have a long pot life, while thermosetting resins have large adhesive strength and excellent heat resistance. It may be appropriately selected and used according to the purpose of use.

As the thermoplastic resin, a polyamide type,
Polyester type, ionomer type, ethylene / vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EM
Examples thereof include A), olefins such as ethylene / ethyl acrylic (EEA), various synthetic rubbers, thermoplastic elastomers, and modified products and composites thereof. Examples of thermosetting materials include epoxy resin-based, urethane-based, acrylic-based, silicone-based, chloroprene-based, nitrile-based synthetic rubbers, and mixtures thereof.

As the conductive particles imparting anisotropic conductivity, metal particles such as gold, silver, copper, nickel, palladium, stainless steel, brass, solder, etc., ceramic particles such as tungsten carbide, silicon carbide and carbon are used. , Graphite particles, carbon short fibers, or surfaces of the conductive particles or insulating plastic particles which are coated with a metal.

If the amount of these conductive particles dispersed and mixed in the insulating adhesive is too small, the particles will not exist on the electrode terminals to be connected, impairing conduction, and if too large, they will stochastically connect in the planar direction. Since the anisotropy is lost, the range of 0.1 to 30 parts by volume is preferable with respect to 100 parts by volume of the adhesive solid content, preferably 1 to 15 parts by volume. When the conductive particles are dispersed in the conductive line forming paste, less than the above capacity part can be added to 100 parts by volume of the solid content of the conductive paste, and the insulating property on the conductive line can be improved. All that is required is to provide an adhesive.

The particle size of these conductive particles depends on the coating thickness of the insulating adhesive, the pitch of the conductive lines, etc.
It is determined in consideration of characteristics such as connection stability, reliability, and peel strength, but the one having a size of approximately 5 to 100 μm is selected, and the shape thereof is not particularly limited, and the shape is granular, scale-like, plate-like, Spherical, dendritic, dice-shaped, spheroidal and irregular shapes are used.

The insulating adhesive may be provided on the conductive line by printing the liquid adhesive in a screen printing method such as screen printing or gravure printing, roll coating, bar coating or spray coating. It can be applied by a known method such as coating, but if necessary, as a solvent, an ester type, a ketone type, an ether ester type used to dissolve the binder resin of the conductive paste. It is also possible to use a chlorinated hydrocarbon type, an ether type, an alcohol type, a hydrocarbon type or the like.

[0029]

According to the method of manufacturing the heat seal connector of the present invention, the conductive paste before passing through the opening of the screen plate is passed through the screen before and after passing through the opening of the screen plate. Indirectly, for example, by heating the plate with a heater or the like, the temperature is maintained at, for example, 30 to 50 ° C., and the past paste is immediately cooled at 0 to 25 ° C. by keeping the substrate to be printed cooled. The viscosity of the paste is changed from 100 to 700 poises to 1000 poises or more by controlling the temperature difference to 10 ° C. or more to control the flow of the conductive paste immediately after printing. It is possible to obtain a clear and fine conductive line which is as wide as the screen opening width or about 10 μm wide.

[0030]

The present invention will be described in more detail with reference to specific examples. Examples 1 to 8 Conductive paste (1): molecular weight 20000 to 25000,
Glass transition point 20 ° C., hydroxyl value 6.5 KOHmg / g,
11 parts by weight of a saturated copolyester resin having an acid value of 1.5 KOHmg / g, an average particle diameter of 4.3 μm, and a specific surface area of 0.8 m
85 parts by weight of ² / g scale-like silver powder, carbon powder manufactured by Columbia Carbon Co., Ltd. (trade name: Conductex 975)
Ethyl acetate carbitol was added to 4 parts by weight of 2.2 parts by weight of Polyurethane Co., Ltd. isocyanate (trade name: Coronet AP Stable M), and the viscosity was 3 at 30 ° C.
Adjust to 50 poise.

Conductive paste (II): molecular weight 15,000-
-20,000, glass transition point 7 ° C, hydroxyl value 5.5KO
11 parts by weight of saturated copolyester resin having Hmg / g and acid value of 2.0 KOHmg / g, 85 parts by weight of scaly powder having an average particle size of 4.3 μm and a specific surface area of 0.8 m ² / g, manufactured by Nippon Aerosil Co., Ltd. Dry silica (Product name Aerosil # 30
0) 1 part by weight, isocyanate manufactured by Nippon Polyurethane Co., Ltd.
TO (Brand name CORONET AP Stable M) 1.8
Add ethyl acetate carbitol to parts by weight and adjust to a viscosity of 220 poise at 40 ° C.

Screen plate (I): wire diameter 27 μm, thickness 4
0 μm, aperture ratio 43%, (aperture ratio / thickness ratio 1.08)
Test plate having 400 openings with a pitch of 0.30 mm, an opening width of 0.145 mm, and an opening length of 35 mm on a calendar-processed stainless steel screen.

Screen plate (II): wire diameter 27 μm, thickness 2
Nickel electroformed screen with 0 μm, aperture ratio 34%, (aperture ratio / thickness ratio 1.7) has a pitch of 0.20 mm, an aperture width of 0.09 mm and an aperture length of 45 mm.
The book had a test version.

Screen plate (III): wire diameter 27 μm, mesh thickness 20 μm, aperture ratio 43%, (aperture ratio / mesh thickness ratio 1.0
A test plate having 600 openings having a pitch of 0.30 mm, an opening width of 0.10 mm, and an opening length of 35 mm in a calendar-processed stainless steel screen of 8).

Screen plate (IV): wire diameter 27 μm, thickness 2
Nickel electroformed screen of 0 μm, opening ratio 34%, (opening ratio / thickness ratio 1.7) has a pitch of 0.20 mm, an opening width of 0.05 mm and an opening length of 45 mm and 600 openings.
The book had a test version.

The above-mentioned two kinds of conductive pastes and four kinds of screens
A conductive line was created on the polyester film printed circuit board using the printing plate. In each experiment, the conductive paste was heated and the substrate was cooled from the back side to a predetermined temperature. The respective conditions and the state of the formed conductive line are summarized in Tables 1 and 2 below. The temperature in the table is ° C.
The width of the conductive line is mm.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

According to the present invention, when a conductive line having the same width as the conventional one is to be obtained, the width of the screen opening can be set, so that a fine conductive line without constriction, disconnection or bleeding can be obtained. Lines can be easily obtained, production efficiency is high, and it has become possible to print fine conductive lines that were previously unusable industrially, which was the limit of screen printing in the past.
A heat seal connector having a high-definition pattern is provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a printing machine showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Printed substrate 2 ... Conductive paper
Stroke 3 ... Screen opening 4 ... Mesh 5 ... Mask material 6 ... Heater 7 ... Squeegee 8 ... Paste return 9 ... Windshield 10 ... Heat medium inlet / outlet port 11 ... Refrigerant inlet / outlet port 12 ... Table 13 ... Metal frame

Claims (2)

[Claims] 1. A plurality of conductive lines formed of a conductive paste and having a width substantially half the conductive line pitch are formed on an insulating polymer film, and an insulating adhesive layer and an insulating adhesive layer are formed on the surface of these conductive line groups. In a method for manufacturing a heat seal connector in which a layer electrically connected to an electrode to be connected via conductive particles is formed, a heated conductive paste is passed through a screen opening and then passed through. After cooling, the difference between the width of the conductive line and the width of the screen opening is set to 10 μm or less and 0.3 m.
A method for manufacturing a heat seal connector having a fine pitch pattern, characterized in that conductive lines having a pitch of m or less are formed. 2. The temperature difference between the heated temperature before passing through the screen opening of the conductive paste and the cooled temperature after passing through it is 10 ° C. or more. 1. A method for manufacturing a heat seal connector according to 1.