JP2743958B2 - Composite adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite having a silicone rubber having an adhesive portion and a non-adhesive portion on the surface. The composite according to the present invention is extremely useful for temporarily fixing a substrate, particularly in a step of mounting components on a flexible printed circuit board.

[0002]

2. Description of the Related Art In recent years, when assembling electronic parts or the like, a method of temporarily fixing a sheet-like part or the like with a jig in which an adhesive is applied to a part of a flat surface or a curved surface, and performing various operations. In this method, the adhesive is partially applied to the jig because the adhesive strength is too strong depending on the adhesive, but the adhesive-applied surface and the non-applied surface are about 0.05 to 0.2 mm. The unevenness occurs on the surface of the temporarily fixed component, making it difficult to obtain a uniform smooth surface, and there is a problem in that image distortion is likely to occur in screen printing or the like that requires accuracy. .

As a specific example of performing various operations by temporarily fixing a jig to a jig, there is a process of mounting an electronic component on a flexible printed circuit board in which a polyimide film and a circuit conductor are laminated in the electronics field. The process of mounting electronic components (for example, LSIs, capacitors, resistors, inductors, filters) on flexible printed circuit boards
It consists of a cream solder printing process, an electronic component mounting process, a reflow soldering process, a cutting process, etc.If it is necessary to flatten and fix the flexible printed circuit board in the above process and transport between processes, it is conventionally made of metal This has been dealt with by attaching and fixing the substrate on a flat plate with a heat-resistant tape. However, in this method, attaching and detaching with a heat resistant tape is troublesome, which is disadvantageous in terms of mass productivity and cost.

In this case as well, the components can be mounted by temporarily fixing the flexible printed circuit board to a jig coated with an adhesive, but depending on the shape and size, a portion where the adhesive strength is too strong or where the adhesive is not desired to be adhered. In some cases, a jig to which an adhesive is partially applied is used, and there is a problem that it is difficult to obtain the flatness of the flexible printed circuit board due to the step as described above.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present invention relates to a composite jig having an adhesive portion and a non-adhesive portion on its surface, which is used when a sheet-like component is temporarily fixed. The purpose of the present invention is to provide one that can obtain flatness.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that organohydrogenpolysiloxane is applied to a predetermined portion of the surface of an addition-curable silicone rubber having a tackiness. It has been found that a target composite adhesive body can be obtained by forming a non-adhesive portion by applying and reacting a liquid containing the same, thereby achieving the present invention.

Hereinafter, the present invention will be described in detail. In the composite pressure-sensitive adhesive body of the present invention, the pressure-sensitive adhesive portion and the non-pressure-sensitive adhesive portion are substantially on the same surface, so that there is no step at the boundary between them. Further, the composite pressure-sensitive adhesive body of the present invention is preferably formed by coating or the like on a heat-resistant strong substrate such as a metal plate. Since the composite pressure-sensitive adhesive body is made of silicone rubber, it has excellent heat resistance as a whole. Since it is easy to handle, it is advantageous for various steps recommended by temporary fixing when used as a jig.

The silicone rubber composition used for producing the composite pressure-sensitive adhesive body of the present invention is not particularly limited as long as it has an adhesive property as long as it is an addition-curable type. Silicone rubber compositions include peroxide-curable, condensation-curable and UV-curable types,
Although these cannot be used, it is desirable to use an addition-curable type for the purpose of the present invention. This is because, according to the combination of the addition-curable type and the organohydrogenpolysiloxane, it is easy to detackify substantially on the same surface, and the addition-curable type material is easy to control the cross-linking density. This is because it has excellent heat stability after curing.

The addition-curable silicone rubber composition used for forming the adhesive portion of the composite adhesive body of the present invention typically comprises (A) an alkenyl group having at least two alkenyl groups in one molecule. (B) Organopolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule (C) Platinum group metal-based catalyst (D) Filler

The organopolysiloxane as the component (A) has at least two alkenyl groups in one molecule. Examples of the alkenyl groups include vinyl, allyl, methallyl, hexenyl and the like. A lower alkenyl group can be mentioned. The organic group other than the alkenyl group may have 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms.
Has an unsubstituted or substituted monovalent hydrocarbon group.
Specific examples of such a hydrocarbon group include alkyl groups such as methyl group, ethyl group, propyl group and butyl group; cycloalkyl groups such as cyclohexyl group; aryl groups such as phenyl group and tolyl group; benzyl group and phenylethyl group. Aralkyl groups; and groups in which part or all of the hydrogen atoms of these groups have been substituted with halogen atoms, for example, chloromethyl group, 3,3,3-trifluoropropyl group and the like.

The organopolysiloxane is 25%
It has a viscosity at 100C in the range of 100-200,000 cSt and has a corresponding degree of polymerization. That is, if the viscosity is higher than the above range, the workability of the composition is impaired, and if the viscosity is lower than the above range, the properties of the cured product may be inconvenient. In the present invention, the above-mentioned organopolysiloxanes can be used alone or in combination of two or more.

The molecular structure of the organopolysiloxane is preferably linear, but may be partially branched. Suitable examples of the organopolysiloxane of the component (A) include those represented by the following formulas (1) to (3).

Embedded image (In the above formula, p represents 2 or 3, s, u and w represent positive integers, and t, v and x represent 0 or positive integers.)

The organohydrogenpolysiloxane as the component (B) functions as a crosslinking agent for the alkenyl group-containing organopolysiloxane of the component (A), and contains a hydrogen atom directly bonded to a silicon atom in one molecule. Is used. That is, the alkenyl group in the component (A) and the Si in the component (B)
By the addition reaction with the H group, a sticky cured product of the rubber elastic body is formed. In this organohydrogenpolysiloxane, the hydrogen atom may be bonded to any silicon atom at the molecular end or in the middle of the molecular chain. Examples of the organic group bonded to the silicon atom include groups other than the alkenyl group exemplified in the organopolysiloxane of the component (A). The organohydrogenpolysiloxane may have a linear, branched, or cyclic structure,
These mixtures may be used. Further, these organohydrogenpolysiloxanes preferably have a polymerization degree of 300 or less. The following is a suitable example.

[0014]

Embedded image (In the above formula, b, c, d, e, f, g, and i represent 0 or a positive integer, and h represents an integer of 2 or more.)

[0015]

Embedded image (In the above formula, R represents a hydrogen atom, a methyl group, a propyl group, or a trimethylsiloxy group.)

The organohydrogenpolysiloxane is used in an amount sufficient to supply 0.1 to 3.0 hydrogen atoms bonded to silicon atoms per alkenyl group contained in the organopolysiloxane (A). ,
Preferably, the molar ratio of the SiH group to the alkenyl group is 0.2 to 1.
It is used in such a ratio that it becomes 2.

The platinum group metal-based catalyst of the component (C) is a catalyst for an addition reaction between the alkenyl group and the SiH group, and acts as a curing accelerator. Such catalysts include platinum-based, palladium-based, and rhodium-based catalysts, and any of these can be used. In the present invention, a platinum-based catalyst is particularly preferred, but is not limited thereto.For example, platinum platinum, alumina, silica or the like on which solid platinum is supported, chloroplatinic acid, alcohol-modified chloride Platinic acid, complexes of chloroplatinic acid with olefins and the like can be suitably used.

When these catalysts are used, when they are solid catalysts, they are preferably finely crushed to improve dispersibility, or the support is preferably made to have a small particle size and a large specific surface area. As for the complex of chloroplatinic acid and an olefin, it is desirable to use them after dissolving them in a solvent such as alcohol, ketone, ether or hydrocarbon. The amount of these catalysts can be used to obtain a desired curing rate with a so-called catalyst amount. However, in order to obtain an economic viewpoint or a good cured product, it is preferable to use the following ratios. That is, for those which are compatible with the siloxane component such as chloroplatinic acid, 0.1 to 100 ppm with respect to the total amount of the components (A) and (B).
(Equivalent to platinum) and 20 for solid catalysts such as platinum black.
It is preferable to be within the range of 500 ppm (in terms of platinum).

As the filler of the component (D), all of those generally used for addition-type silicone rubber compositions can be used. Specifically, fumed silica,
Precipitated silica, hydrophobically treated silica, titanium dioxide,
Ferric oxide, aluminum oxide, zinc oxide, quartz powder,
Diatomaceous earth, calcium silicate, talc, bentonite, asbestos, glass fiber, organic fiber and the like are used alone or in combination of two or more. The amount of the filler is arbitrary as long as the object of the present invention is not impaired,
Generally, it is not more than 600 parts by weight per 100 parts by weight of the organopolysiloxane of the component (A). Among them, the fumed silica is preferably 25 parts by weight or less, and in the case of alumina or the like, the range of 300 to 500 parts by weight is suitable, and the oil absorption of the filler, the surface area, and the specific gravity are suitable. The amount of addition differs.

As other components, in order to reinforce the cured product, apart from the filler of component (D), the composition contains SiO ₂ units, Vi (R ′) ₂ SiO _0.5 units and R ′ ₃ SiO _0.5 units (Vi is a vinyl group and R 'is a monovalent hydrocarbon group containing no unsaturated aliphatic group).
No. 38-26771, JP-B-45-9476, etc.). Further, for the purpose of controlling the curing rate of the composition, an organopolysiloxane having ViR'SiO units (R 'is the same as described above) (see Japanese Patent Publication No. 48-10947) and disclosed in U.S. Pat. No. 3,445,420. Acetylene compound, and ionic compounds of heavy metals disclosed in U.S. Pat.No. 3,532,649 specification, and the like. An organopolysiloxane can also be blended. Furthermore, a heat-resistance improving agent such as cerium oxide, a flame retardant imparting agent such as titanium oxide, benzotriazole, zinc carbonate, and manganese carbonate, an addition reaction controlling agent such as a vinyl group-containing siloxane and an acetylene compound, and a foaming agent are appropriately added. be able to. In the present invention, the amounts of the various additives to be added as required must be such that the tackiness when the composition is cured is not impaired.

Further, a known adhesion aid may be added to the composition to improve the adhesion to the substrate. For example, those having an alkoxysiloxy group (Japanese
No. 53-21026), those having an epoxy-containing hydrocarbon group (see Japanese Patent Publication No. 53-13508), those having an alkoxysiloxy group and an epoxy-containing hydrocarbon group (Japanese Patent Publication No. Sho.
No. 59-5219), and those which are particularly preferably used are those represented by the following formula.

[0022]

Embedded image

These organosilicon compounds as an adhesion promoter can be used by appropriately increasing the degree of polymerization and the like, if necessary. The organosilicon compound is used in an amount of 0.1 to 100 parts by weight of the organopolysiloxane of component (A).
It is desirable to use 20 parts by weight, especially 1 to 10 parts by weight.

Next, the silicone rubber composition comprising the above-described components is cured at room temperature or by heating to form an adhesive portion. In this case, a strong and heat-resistant base such as a metal plate or a ceramic plate is used. It is good to apply and cure on the material. A known method can be used as the coating method, and examples thereof include a screen printing method, a dipping method, a doctor blade method, a knife coating method, a bar coating method, and a spin coating method.

After forming the adhesive portion, a non-adhesive portion is formed at a predetermined portion on the surface of the adhesive portion. The organohydrogenpolysiloxane used in this method is applied as it is (liquid), or is applied as an organic solvent solution to a predetermined portion on the surface of the adhesive portion, the solvent is volatilized, and the reaction is allowed to proceed to remove the applied portion. It becomes sticky. It is considered that the non-adhesion is caused by the permeation of the organohydrogenpolysiloxane into the surface layer of the silicone rubber in the applied portion and a reaction to increase the crosslink density.

The organohydrogenpolysiloxane used herein typically has three or more hydrogen atoms directly bonded to one molecule in one molecule, and preferably has five or more hydrogen atoms in one molecule. It has a hydrogen atom directly connected to a silicon atom. The organohydrogenpolysiloxane may have a linear, branched or cyclic structure, or may be a mixture thereof. Also,
This organohydrogenpolysiloxane has a degree of polymerization
It is preferably a low-viscosity one of 100 or less, and when diluted with an organic solvent such as toluene, it can be used up to a polymerization degree of about 300. This is considered to be because a low degree of polymerization easily penetrates into the surface layer of the cured adhesive silicone rubber, and good results are obtained. Examples of such an organohydrogenpolysiloxane include those exemplified as the component (B) of the addition-type silicone rubber composition, in which three or more hydrogen atoms are directly bonded to silicon atoms.

The organohydrogenpolysiloxane is adhered to a predetermined portion by sticking a film or sheet made of polyethylene, polyethylene terephthalate, or the like having a hole in the adhesive portion, and applying it only to the hole portion with a brush, spray, or the like. be able to. Further, a screen or a metal mask may be used. After application, the composition may be cured by heating, but it is desirable to wipe off excess organohydrogenpolysiloxane on the surface. Thereafter, the applied portion is made non-adhesive by heating and curing. Moreover,
In this way, the surface step between the adhesive portion and the non-adhesive portion is several μm.
Since the material becomes substantially smooth as described below, a highly accurate product can be supplied without unevenness on the surface of the material to be adhered and fixed on the composite.

[0028]

EXAMPLES Examples will be shown below, but they show specific examples, and the present invention is not limited to the examples. In addition, the part in an example shows a weight part, and the viscosity shows the numerical value in 25 degreeC. <Example 1> 100 parts of an organopolysiloxane having a viscosity of 10,200 cs and containing both ends of a trimethylsilyl group-blocked vinyl group, consisting of 95 mol% of dimethylsiloxane units and 5 mol% of methylvinylsiloxane units, 1,3,5,7-tetramethyl- 1,3,5,7-
1.0 part of tetravinylcyclotetrasiloxane, 45 parts of crystallite VX-X (silica, trade name, manufactured by Tatsumori), fumed silica 10 whose surface is blocked with a trimethylsilyl group
After mixing uniformly, 0.3 part of a solution of chloroplatinic acid in 2-ethylhexanol (platinum content: 2%) was uniformly mixed, and the formula was further added.

Embedded image Then, 5.6 parts of methyl hydrogen polysiloxane represented by the formula (1) was added and mixed uniformly to prepare an addition-curable adhesive silicone rubber composition I.

Next, an aluminum plate (200 × 250 × 3.0 m
m), the addition-curable adhesive silicone rubber composition I obtained above was applied to a thickness of 250 μm by a bar coating method in a thickness of 250 μm.
After coating on an area of 80 × 230 mm, the silicone rubber composition was cured by heating at 150 ° C. for 30 minutes. Then, a masking sheet made of polyethylene terephthalate having a hole as shown in FIG.

Embedded image Was coated with a brush, the masking sheet was removed after the coating, the mixture was left for 10 minutes, and then heated and cured at 150 ° C. for 30 minutes.

The portion coated with methyl hydrogen polysiloxane later becomes non-adhesive, and there is substantially no step at the boundary between the adhesive portion and the non-adhesive portion. Was obtained. The adhesive force between the adhesive part and the non-adhesive part of this composite adhesive
When measured (180 peel) according to SZ0237, the adhesive part was 130 g / 3 cm and the non-adhesive part was 2 g / 3 cm.

An example in which the obtained composite pressure-sensitive adhesive body is applied as a fixing jig for a flexible printed board will be described. A polyimide flexible printed board on which a copper circuit pattern is formed is tightly fixed on the composite adhesive, cream solder is screen-printed, electronic components are mounted, and a halogen lamp is used at 240 ° C. for 30 seconds. Solder reflow was performed. After that, let it cool down to room temperature, peel off the composite adhesive body that fixed the flexible printed circuit board,
A flexible printed circuit board with electronic components has been completed.

Example 2 60 parts of dimethylpolysiloxane having a viscosity of 5000 cs and a dimethylvinylsiloxy group at both ends blocked,
10 parts of fumed silica with a surface area of 200 m ² / g are added to 40 parts of dimethylpolysiloxane having a viscosity of 800 cs, one end of which is blocked with dimethylvinylsiloxy group and the other end with trimethylsiloxy group.
The mixture was heated to 160-170 ° C in a kneader and kneaded.
After cooling, 0.2 part of a 2-ethylhexanol solution of chloroplatinic acid (2% platinum content) was mixed, and 0.002 part of ethynylcyclohexanol was added.

Embedded image 0.8% of methyl hydrogen polysiloxane represented by
Part, expression

Embedded image Was added, and the mixture was uniformly mixed and defoamed to prepare an addition-curable adhesive silicone rubber composition II.

Next, a chrome-plated surface with a width of 250 mm,
An addition-curable adhesive silicone rubber composition II having a thickness of 500 μm was applied to the surface of a drum having a diameter of 100 mm with a knife coater, and cured by heating at 150 ° C. for 30 minutes. afterwards,
Formula with a width of 185mm at the center of the drum

Embedded image Was applied with a gauze and left for 30 minutes to perform impregnation and volatilization of toluene. Then 150 ℃
Detackification was performed by heating for 30 minutes.

When the adhesive strength was measured in the same manner as in Example 1, the adhesive portion was 95 g / 3 cm, and the non-adhesive portion was 1 g / 3 cm.
A polyimide flexible printed circuit board having a width of 210 mm and a length of 290 mm was adhered and fixed to the composite adhesive drum body, and the spot displacement of cream solder at 0.5 mmφ was able to keep the displacement within 0.03 mm.

[0035]

According to the present invention, a composite adhesive body having an adhesive portion and a non-adhesive portion having substantially no steps on the surface is provided. The adhesiveness of this composite adhesive can be adjusted, and excellent flatness is obtained when a sheet-like component is temporarily fixed to the composite adhesive, and it is extremely useful as a jig when mounting electronic components on a flexible printed circuit board. It is suitable.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a masking sheet used in Example 1.

FIG. 2 is an explanatory diagram of a composite pressure-sensitive adhesive body obtained in Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyethylene terephthalate sheet 2, 2 'hole 3, 3' Non-adhesive part 4 Adhesive part 5 Aluminum plate

Claims (1)

(57) [Claims] 1. A composite comprising an addition-curable silicone rubber having an adhesive portion and a non-adhesive portion substantially coplanar on the surface, wherein the non-adhesive portion is a cured addition-curable silicone. A composite pressure-sensitive adhesive body formed by applying and reacting a liquid containing an organohydrogenpolysiloxane to a predetermined portion of a rubber surface.