JPS58152033A - Anisotropic electrically conductive rubber sheet - Google Patents

Abstract

PURPOSE:The titled rubber sheet, prepared by subjecting an unhardened composite material consisting essentially of particles of an electrically conductive magnetic material and an insulating high polymeric elastomer, and having improved dimensional absorption characteristics. CONSTITUTION:An anisotropic electrically conductive rubber sheet prepared by adding a crosslinking agent, e.g. mono-, di- or trialkyl titanate, to a mixture consisting of particles of an electrically conductive magnetic material, e.g. nickel, and an insulating high polymeric elastomer, e.g. polybutadiene, kneading the resultant mixture, casting the resultant unhardened composite material 6, e.g. containing colloidal silica, into a mold body 5, deaerating the composite material 6 under reduced pressure, covering the composite material 6 with the top plate 4 of the mold body 5, nipping the composite material 6 and top plate 4 between electromagnets 1 through heaters 3, treating the composite material 6 in a magnetic field at 4,000 gausses parallel magnetic field intensity at room temperature for 20min, and crosslinking the composite material at 75 deg.C for 2hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an anisotropically conductive i material with excellent dimensional absorption characteristics, which is composed of conductive magnetic particles (hereinafter referred to as magnetic particles) and insulating polymeric elastic bodies (hereinafter referred to as elastic bodies). Regarding rubber sheets.

Fine mechanical parts are often used in the electronics industry,
As packaging density improves, the mounting method for these boards has changed.
It has become a sad problem. In other words, most of the mounting methods up until now have been by soldering, but since electronic components such as semiconductor elements are generally sensitive to heat, it is not desirable to expose them to high temperatures, even temporarily, as this may damage one component. It is difficult and rare to attach components to the board without any damage. In addition, up until now, the mounting of printed circuit boards onto the main body has mainly been done by mechanical interlocking methods, but this has resulted in wear of the contact parts.

There were problems with poor contact due to vibration, etc.

Recently, anisotropically conductive rubber sheets (for example, JP-A-49-51
593. Japanese Patent Publication No. 51-93393. % Kaisho 5353
796,% Opening 52-65892) It has become clear that the above problems can be improved by using it as a T-connector. In some cases, the performance may not always be satisfactory, such as in mounting that places particular emphasis on vibration isolation, or in mounting that requires contact over a large area, such as in printed circuit board inspection applications.

In order to solve the above problems, the present inventors have conducted extensive research and found that the characteristics of the anisotropically conductive rubber sheet that are required for the above installation are more important than the surface resolution or sensitivity.
The present invention was developed based on the knowledge that even if the contact surface (contact surface) has some irregularities, a reliable contact can be achieved with a relatively small clamping pressure (applying force), that is, dimensional absorption characteristics are important. It's arrived.

That is, the present invention is based on the hardness (JISA
Determined according to HB. ) is from 25 to 45, an anisotropically conductive rubber sheet, particularly an anisotropically conductive rubber sheeter used for inspecting printed circuit boards.

What is an anisotropically conductive rubber sheet in the present invention?

The rubber sheet is electrically conductive in only one direction by applying pressure to the rubber sheet.

(For example, conduction occurs in the vertical direction, but not in the horizontal direction.) The conductivity is described in Examples.

As magnetic particles that can be used in the present invention, for example, iron, nickel, cobalt, alloys thereof, and plated particles obtained by plating these with silver, gold, etc.It is also possible to use magnetic particles in combination. The particle size of the magnetic particles is generally determined by the thickness of the anisotropically conductive rubber sheet, but is preferably 10 to 100 μm.

Elastic bodies used in the present invention include polybutadiene, natural rubber, and polyisoprene.

8BR, NBR, EPDM, E)'M, urethane rubber,
Examples include polyester rubber, chloroprene, epichlorohydrin rubber, silicone rubber, etc., but when weather resistance is required, rubbers other than diene rubber are preferred.

The uncured composite used in the present invention is made by adding a crosslinking agent, preferably a mono-, di- or tri-alkyl titanate described later, and in some cases a hardness modifier to a mixture consisting of magnetic particles and an elastic material. The nine examples are composites that are thoroughly mixed by mechanical means such as twin-screw kneading.

The preferred amount of magnetic particles added is 25% to 25% by volume based on the uncured composite.

Mono-, di- or trialkyl titanates are represented by the general formula below.

1 (R(J)-T i ((JRm)m(R(J)-
Ti (COX bird).

(Here, K is an alkyl group having 1 to 4 carbon atoms.

kL& is a vinyl group or an alkyl group having 6 or more carbon atoms.

represents an aralkyl group or an aromatic compound, a bird represents an alkyl group having 6 or more carbon atoms, an aralkyl group, an allyl group, or a derivative thereof, and X represents -S-2 or 1 represents -P-. Furthermore, di-alkyl titanate and trialkyl titanate can be represented by the following general formula.

(RO)nTi (OR')4-n (n=21* is 3) where R is an alkyl group, and from the viewpoint of 9 reactivity, an alkyl group having 1 to 4 carbon atoms is particularly preferred. It is necessary that the ligand (a'o-) other than the secondary alkoxy (RO) is less likely to be hydrolyzed than the bond between the alkoxy group and titanium. Examples of R1 include triethanolamine residue and acyl group.

Aroyl group, acryloyl or methacryloyl groupe
Furkylbenzenesulfonyl group, carbon number 6 or more 1
% preferably includes 10 or more alkyl groups or derivatives thereof.

Examples include isopropyl triisostearoyl titanate, inclovir trilauryl titanate, isopropyl trimyristyl titanate, and isopropyl dimethacroyl titanate.

Isopropyl tri(dodecylbenzenesulfonyl) titanate, inglobil isostearoyl diacroyl titanate, isopropyl tri(diiguoctyl phosphite) titanate.

Isopropyl dimethacroyl titanate, isopropyl tri(dioctylpyrophosphite) titanate, isopropyl triacroyl titanate, isopropyl tri(dioctyl 7-osphite) titanate, butyl triisostearoyl titanate, ethyl triisostearoyl titanate, bis(triethanolamine) diiso Globil titanate, bis(triethanolamine)
Dibutyl titanate, bis(triethanolamine) diethyl titanate, bis(triethanolamine) dimethyl titanate.

Diisopropyl dilauryl titanate, diisoglobil distearoyltetanate, diisopropyl-lauryl-myristyl titanate.

Diisopropyl stearoyl methacrylic titanate, diisocrovir didotecylbenzenesulfonyl titanate, diisoglopyldiacryl tetanate, diisopropylisostearoyl-4-aminobenzoyl titanate, triisopropyl acryloyl titanate, triethyl methacryloyl titanate, triine 10-pyl myristyl titanate, Triz Examples include tildodecylbenzenesulfonyl titanate and triisopropylisostearoyl titanate.

The preferred amount of mono-, di-, or trialkyl titanate added is 0.05 to 0.05 to 0.05 to 0.05 to 0.05 to 0.05 to 0.05 to 0.05 to 0.05 to 0.05 to 0.05.
It is 2%. By adding mono-, di-, or trialkyl titanate, mixing and molding become easier, and the mechanical properties (durability) and electrical properties of the anisotropically conductive rubber sheet are improved.

The crosslinking agent used in the present invention is a commonly used crosslinking agent for rubber. As a hardness regulator, use RTV (manufactured by Shinetsu Chemical Co., Ltd.).

1204 thinner (manufactured by Shin-Etsu Chemical) etc.

The anisotropically conductive rubber sheet of the present invention is obtained by subjecting an uncured composite mainly composed of magnetic particles and an elastic material to a magnetic field treatment and crosslinking it. Must be between 25 and 45. If the hardness is less than 2 (1-2), for example, if the rubber sheet is used as a connector, the durability will be extremely deteriorated due to repeated deformation. Also, the mechanical strength will decrease, so it will not last for a long time. If the contact is maintained, it will not break. - If the hardness exceeds 45, for example, when the rubber sheet is used as a connector, the clamping pressure required to maintain normal conduction will be high, and the flatness must be maintained fairly strictly. You can only touch the parts that have been touched.

In the present invention, the time for applying the magnetic field and the intensity of the magnetic field may be such that the uniformly dispersed magnetic particles in the elastic body are aligned by the magnetic field and are sufficiently stabilized. For example, in the case of RT-V type silicone rubber, it is sufficient to apply a magnetic field strength of 2,000 Gates or more for about 10 to 60 minutes.

In general, crosslinking of the uncured composite in the invention is performed after subjecting the uncured composite to magnetic field treatment.

This is done by leaving it as it is and leaving it at a temperature.

1) It is also possible to crosslink by lowering the temperature while applying magnetic field treatment.

What is the thickness of the anisotropically conductive rubber sheet of the present invention?

It is determined from a practical standpoint, but preferably 0.5 to 1
O■, more preferably 1 to 5 m.

The uncured composites used in the present invention include colloidal silica, silica aerogel, kaolin, mica, Merck, wollastonite, calcium silicate, aluminum silicate, chalk, calcium carbonate, iron oxide, alumina, etc.
Volume fraction (2)) may be included, but adding a large amount deteriorates compression set and electrical properties, which is not practical.

However, when mixing magnetic particles into the prepolymer, it is preferable to mix an appropriate amount of filler in order to prevent rearrangement of the magnetic particles after crosslinking.

Additionally, additives such as process oil can be added as necessary.

Since the anisotropically conductive rubber sheet of the present invention has low hardness and low clamping pressure, it not only has excellent one-dimensional absorption properties, but also extremely excellent current capacity, absolute # properties, mechanical properties, etc. Therefore.

The anisotropically conductive rubber sheet of the present invention is most suitable for use as a connector used over a large area.

The following 9 F! The i4 will be explained using an example.

However, the invention is not limited to this embodiment, but does not go beyond the gist of the invention.

Example 1. Comparative Example 1 Additive silicone rubber (KE1206RT manufactured by Shin-Etsu Chemical Co., Ltd.
V), nickel particles with a volume fraction of -
-) and a predetermined amount of crosslinking agent.

Additives for hardness adjustment (No additives were used in Comparative Example 10) (RTV Thinner manufactured by Shin-Etsu Chemical) were mixed in a vacuum for 60 minutes using a twin-screw kneader, and then the mixture shown in Figure 1 was mixed. As shown, it is poured into a mold 5 made of magnetic material of a predetermined thickness. After sufficiently foaming under vacuum, the top plate of the magnetic mold 4 was covered with a lid, and an electromagnet was placed between 10 and 10 times through a heater 3T. Processed for minutes. Next, the temperature was raised to about 75 DEG C., and crosslinking was carried out for 2 hours to obtain a rubber sheet having a thickness of 2 cm and %/-h.

The anisotropic conductivity of the rubber sheet was confirmed by the method shown in FIG. That is, in FIG. 2, the upper electrode holding plate 9t is replaced with an insulating flat plate.

Although the pressure was within the range, no lateral conduction was observed.

Continuity reliability test results for the rubber sheet! ! ! It is shown in 1. Table 1 shows that the rubber sheet of the present invention has high conductivity reliability.

Continuity Reliability Test> In Fig. 2, a rubber sheet as a sample is sandwiched between the upper electrode printed circuit board 8 and the lower electrode printed circuit board 10, and the upper electrode holding plate 91A is pressed in the direction of the arrow (with no clamping pressure). Anisotropically conductive rubber sheets of various thicknesses with the same composition as Opposed-4 (same composition as Experiment Nos. 1-1' and 1-3' in Comparative Example 1) were prepared in the same manner as in Example 1. A conduction reliability test was conducted on the unevenness of the contact surface of the rubber sheet using the method shown in Figure jIN3. The results are shown in [2]. Table 2 shows that the non-inventive rubber sheet has excellent dimensional absorption characteristics.

As shown in Figure 3, spacers 13 of various thicknesses were inserted between the lower electrode printed circuit board 10 and the lower electrode holding plate 11 to provide a step, and the rubber sheet serving as sample 7 was made to have an uneven surface. A continuity reliability test was conducted.

Example 3. Comparative Example 3 Same composition as Experiment No. 1-3 in Example 1. The results are shown in Table 3. The durability test is to pressurize the rubber sheet repeatedly and determine the number of times the rubber sheet is repeatedly pressurized until the result of the continuity reliability test changes from ◎ to △. From Table 3, it can be seen that the addition of a titanium coupling agent greatly improves the durability. The conductivity reliability test results were the same as in the case of a rubber sheet without the addition of a titanium coupling agent.

1 storm

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus that applies a magnetic field to an uncured composite, and FIGS. 2 and 3 are diagrams showing a method for testing continuity reliability. 1... Electromagnet, 2... Heating plate, 3... Heater, 4
- Mold upper plate 5...Mold body, 6...Uncured composite
7... Rubber sheet 8... Upper electrode printed circuit board 9
... Upper electrode holding plate 10... Lower electrode printed board 11... Lower electrode holding plate 12, 12'... Electrode 13... Spacer patent applicant Japan Synthetic Rubber Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (Hardness obtained by crosslinking an uncured composite body mainly composed of conductive magnetic particles and an insulating polymer elastic body and containing a crosslinking agent by subjecting it to a magnetic field treatment (determined according to J18AHB) is 25~ 45. An anisotropically conductive rubber sheet characterized by a