JPS5821893A - Method of producing flexible printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an adhesive for bonding a metal foil to a plastic film having a melting point of 260° C. or higher. 10 parts by weight of a polyorganosiloxane having 2 or more hydrogen atoms and an average degree of polymerization of 50 to 10,000; (B) a polyorganohydrodiene siloxane having an average number of more than 2 hydrogen atoms bonded to silicon atoms in the molecule; , an amount in which the hydrogen atom is 0.5 to 10 moles per mole of the vinyl group bonded to the silicon atom in (Δ), (C) 20 to 150 parts by weight of a silica filler, (D)
Iron oxide or (and) 0.5 to 20 parts by weight of carbon black represented by the general formula (FeO) 1 to 200 ppm as compound platinum atoms,
(F) At least one hydrogen atom bonded to a silicon atom in the molecular chain in the molecule, the general formula % and Q2 are linear or branched alkylene groups that are the same or different from each other, and R is carbon It represents an alkyl group of numbers 1 to 4. )
An adhesive composition consisting of 0.5 to 50 parts by weight of polysilochitin, which is represented by
A method for manufacturing a flexible printed wiring board, which comprises coating a plastic film or (and) metal foil at 60° C. or higher, drying the film, then overlaying the plastic film and gold am and heat-pressing it, followed by after-keying. It is related to.

With the diversification of electronic equipment, flexible wiring boards that are lightweight and capable of three-dimensional wiring are becoming increasingly popular, but recently there has been a strong demand for twist resistance from a safety standpoint, and particularly stringent flame retardant tests are required. Flame retardancy equivalent to UL 94 V-○, which is the legal standard, is now required. However, although some heat-resistant plastic films such as polyimide films have excellent heat resistance and flame retardancy, they are not suitable for flexible printed wiring, which integrates metal foil and plastic film by heat and pressure bonding via adhesive. Regarding substrates, the characteristics of the adhesive determine the adhesive properties, heat resistance, flame retardance, etc. of the substrate, and it has been extremely difficult to make the adhesive have all of these characteristics. This is a plastic film with a melting point of 260 °C or higher, such as an epoxy resin that is commonly used to exhibit heat resistance as an adhesive between a polyimide film and metal foil, but contains bromine for flame retardancy. This is because when a brominated epoxy resin is used, heat resistance and adhesiveness are significantly reduced.

As a result of various studies, the inventors of the present invention found that by using an addition reaction cross-linked silicone resin as an adhesive, properties such as peel strength and adhesion required for a flexible printed wiring board, soldering heat resistance, flame retardance, etc. They have found that the following requirements are satisfied, and have completed the present invention.

The present invention will be explained in detail below.

As the metal foil in the present invention, conductive metal foils such as copper foil, aluminum foil, nickel foil, and nichrome foil can be used.

Examples of the plastic film in the present invention include polyimide film, polyamide film = 5-ilm, polyamide film, polysulfone film,
A plastic film having a melting point of 260° C. or higher, such as a biaxially stretched polyester film, can be used.

Each component of the adhesive composition will be explained.

廄) Polyorganosiloxane is a base polymer of silicone adhesive and has a substantially linear skeleton.
In order to form a network polymer using (B), it is necessary to have an average of two or more silicon atoms (-bonded vinyl groups) in the molecule.

In addition to the vinyl group mentioned above, organic groups bonded to silicon atoms include methyl group, ethyl group, propyl group, butyl group,
Alkyl groups such as pentyl group, hexyl group, octyl group, decyl group, dodecyl group, aryl group such as phenyl group, aralkyl group such as benzyl group, β-phenylethyl group, β-phenylpropyl group, β- Cyanoethyl group, 3
．． 3.3-) Substituted hydrocarbon groups such as lifluoropropyl group and chlorophenyl group are exemplified, but polydiorganosiloxanes exhibit the characteristics of heat resistance and 6- cold resistance, and are easy to synthesize and handle. In this respect, it is preferable that 85% or more of the organic groups are methyl groups, and it is more preferable that substantially all organic groups other than vinyl groups are methyl groups.

The terminal end of the molecule is usually blocked with a triorganosilyl group such as trimethylsilyl, dimethylvinylsilyl, dimethylphenylsilyl, or hydroxyl group. The average degree of polymerization is preferably in the range of 50 to 10,000 in terms of siloxane units. If it is less than 50, sufficient mechanical strength cannot be obtained due to crosslinking, resulting in weak peel strength. In addition, the viscosity of polydiorganosiloxane is lowered and the blended (0) and fD
) settles, making it impossible to obtain a uniform adhesive layer.

In addition, if it exceeds 10,000, it will be difficult to synthesize (0) and FD), and it will be extremely difficult to uniformly (bidisperse) adhesive side layer 1: sufficient mechanical strength, special feature 1: impact and shear force. The degree of polymerization must be 3,000 to provide strength when working.
The range is preferably from 10,000 to 10,000.

The polyorganohydrodiene siloxane (B) has a silicon-hydrogen bond that is formed by the catalytic action of (B).
By reacting with the vinyl group bonded to the silicon atom of the molecule, the molecule is crosslinked to form a network polymer, and in order to create such a network, hydrogen atoms bonded to the silicon atom in the molecule must be It is necessary to have more than two. The molecular skeleton may be linear, branched, or cyclic. Examples of the organic group bonded to a silicon atom include (argyl group, aryl group, aralkyl group, and] U-substituted hydrocarbons as exemplified in A>), which have good compatibility with (A). In order to achieve this, it is preferable to have the same organic group structure as (A>, and for the same reason as in (A), a methyl group is preferable. The blending amount of (B) is <A,) The hydrogen atoms bonded to silicon atoms in (B) are between 0.5 and 10 moles per mole of vinyl groups bonded to silicon atoms in (B).If less than 0.5 moles, curing will not be sufficient and the soldering heat resistance will be poor. If the amount exceeds 10 mol, there will be a large amount of unreacted silicon-hydrogen bonds remaining even after curing, resulting in a decrease in heat resistance.In addition, in order to provide excellent peel strength, the above-mentioned The amount of hydrogen atoms is preferably between 2.5 and 6 moles.If it is less than 2.5 moles or more than 6 moles, sufficient peel strength cannot be obtained.

The silica-based filler (0) is one that provides mechanical strength, heat resistance, and flame retardancy to the adhesive, and includes strong reinforcing materials such as fumed silica, precipitated silica, silica aerogel, calcined silica, and crushed quartz. , fused silica, and diatomaceous earth, which can be incorporated into the system in large quantities and impart flame retardancy. In order to impart moisture resistance and hot water resistance to the adhesive, the surface of the reinforcing filler described above is treated with an organosilicon compound such as organochlorosilane, polydimethylsiloxane, or hexamethyldisilane to remove some of the silanol groups on the surface. Or it is preferable to modify all of them.

The blending amount of (0) is 20 to 1 per 100 parts by weight of (A).
The amount is 50 parts by weight, preferably 40 to 100 parts by weight. If it is less than 1 part by weight of 20 parts, the peel strength and flame retardance will not be sufficient, and if it exceeds 150 parts by weight, the adhesive layer will become too hard and sufficient peel strength cannot be obtained. Further, in order to obtain excellent flame retardancy, it is preferable that the amount of crushed quartz or fused silica in (C) is 30 to 100 parts by weight. If it is less than 30 parts by weight, sufficient flame retardancy cannot be obtained, and if it exceeds 100 parts by weight, sedimentation tends to occur and a uniform adhesive layer cannot be obtained.

Iron oxide and carbon black (D) impart excellent flame retardancy to the adhesive layer, and have the general formula (Fe0)) x (F
ears )y, and the ratio of X and y is 0.05 to 1.
Iron oxide and carbon black in the range of 0 can be used alone or in combination. When comparing the two, iron oxide provides higher flame retardancy.

If the ratio of X to y of iron oxide is outside the above range, sufficient flame retardancy cannot be obtained. The blending amount of (D) is in the range of 0.5 to 20 parts by weight per 100 parts by weight of (A). If the amount is less than 0.5 parts by weight, the flame retardance will not be sufficient, and if it exceeds 20 parts by weight, the peel strength will decrease.

The platinum compound (E) is produced by converting (A) into (B) by reacting the vinyl group of (A) with the silicon-hydrogen bond of (B).
It is a catalyst for crosslinking, and also a catalyst for crosslinking after curing.
- It is an important component that imparts flame retardancy to adhesives. (E) includes chloroplatinic acid, platinum chloride-olefin complexes, platinum chloride-dialkyl ether complexes, platinum chloride-vinyl group-containing polysiloxane complexes, zero- and divalent platinum-phosphine complexes, and platinum-phosphite complexes, Examples include acetylacetonatoplatinum. The appropriate amount of @) varies depending on its type, but it is 1 to 200 ppm, preferably 5 to 50 ppm as platinum atoms, relative to (A).
is within the range of If (E) is too small, sufficient flame retardancy cannot be obtained, and if it is too large, soldering heat resistance will be reduced.

The polysiloxane (F) has excellent peel strength, and the siloxane skeleton may be linear, branched, or cyclic, but it is usually a linear chain because it is easy to synthesize. A shape or a ring shape is used. Furthermore, although the hydrogen atom and -Q'-C-0Q2Si(OR)3 are usually bonded to separate silicon atoms of the silogenane skeleton, they may be bonded to the same silicon atom. Q' and C2 may be the same or different, and examples include a methylene group, an ethylene group, a propylene group, a butylene group, and the propylene group and the butylene group may be linear or branched. For ease of synthesis and hydrolysis resistance, Ql is a methylene group or a 1,2-propylene group, and C2 is an alkylene group that connects a silicon atom and an ester oxygen atom through at least three carbon chains, especially a 1,3-propylene group. It is preferable that Examples of R include a methyl group, an ethyl group, a propyl group, and a butyl group, and in order to obtain good peel strength, a methyl group or an ether group is preferable. The blending amount of (F) is (A) 10
0.5 to 50 parts by weight, preferably 2 to 50 parts by weight
The range is 10 parts by weight. This is because if the amount is less than 0.5 parts by weight, the adhesiveness will be insufficient, and if it exceeds 50 parts by weight, the heat resistance and flame retardance will be reduced.

In addition, the adhesive may contain other known components such as flame retardants, heat resistance improvers, processing aids and stabilizers when (C) and (Dl are mixed with (A)). There is no problem even if they are combined.

The adhesive of the present invention is usually (A), (C1, (D),
The base consisting of (E) and (G) and the crosslinking agent composition consisting of (B) and (F) are prepared separately, and the base and crosslinking agent composition are mixed immediately before use. A,)
, (C) and/or (a portion of (Gl) may be blended into the crosslinker composition, and (E) may be stored separately.
In the latter case, a part of (8) may be allowed to coexist with (E) for the convenience of mixing.

In the present invention, the plastic film and the metal foil can be bonded together by a conventional method. For example, Tokuko Sho 55-194
38, the plastic film is delivered and an application roll applies adhesive to one side of the film, and then passes through a drying section to dry the adhesive. Meanwhile, the metal foil is sent out and continuously bonded to the adhesive-coated film using a heated pressure roll. Next, the adhesive is after-keyed in a drying oven to improve solder heat resistance and peel strength.

Examples will be described below.

13 Example 1 Adhesives A-1 to A-18 were prepared using the following polysiloxanes S-1 to S-9 at the compounding ratios shown in Table 1. That is, taking A-1 as an example, polysiloxane S-1, fumed silica, and pulverized silica are sufficiently kneaded in a kneader, and further iron oxide and platinum-vinyl siloxane complex are added and kneaded,
I got the base compound. Dilute this with toluene,
Polysiloxane S-4 and S- mixed in advance with this
The mixed solution of No. 6 was blended and sufficiently stirred to obtain adhesive A-1. Adhesives A-2 to A-18 were obtained in the same manner.

Next, the adhesive, for example A-1, was applied to a polyimide film (Kapton, manufactured by Dapon Co., Ltd.) with a thickness of 50 μm to a thickness of about 20 μm after drying, and after drying at 130° C. for 2 minutes, electrolysis was performed to a thickness of 35 μm Laminate the copper foil with a heating roll, 1
After-keying was carried out at 60° C. for 10 hours to obtain a flexible printed wiring board B-1. Similarly, A? ,~A
Flexible print wiring boards B-2 to B-18 were obtained using the adhesive No. 18. The performance of this product is shown in Table 2.

S-1: Polydiorganosiloxa consisting of 0.2 mol% methylvinylsiloxy units and the remaining dimethylsiloxy units, the terminals are blocked with trimethylsilyl groups, and the average degree of polymerization is 7,000] / S-2: 0 .Polydiorganosiloxane S-3 consisting of 2 mol% methylvinylsiloxy units, 8 mol% diphenylsiloxy units and the remainder dimethylsiloxy units, the terminals are blocked with dimethylvinylsilyl groups, and the average degree of polymerization is 5,000. : Polydiorganosiloxane 5-4, consisting of dimethylsiloxy units and having an average degree of polymerization of 1,500, whose ends are blocked by dimethylvinylsilyl groups = Polydiorganosiloxane 5-4, which consists of methylhydrogensiloxy units and whose ends are blocked by trimethylsilyl groups 30 polymethylhydrodiene siloxane S-5: Polymethylhydrodiene siloxane (CH3) consisting of 60 mol% methylhydrodiene siloxy units and the remaining dimethylsiloxy units, with an average degree of polymerization of 50 and whose terminals are blocked with trimethylsilyl groups. 2 Polysiloxane 5-7 = Polysiloxane (CH2)3 CO(CHJa si (OCHs)s) represented by the molecular formula
Polysiloxane S-9 represented by i1: When a polydiorganosiloxane base polymer having an average degree of polymerization of 45 and having the same chemical structure as S-3 is used, it is sufficient to use a polydiorganosiloxane base polymer having an average degree of polymerization of less than 50 (A-10'). peel strength could not be obtained (B-10).

The relationship between the amount of polyorganohydrogensiloxane and performance is A-11 to A14. In B-11 to B-14, if the polyorganohydrodiene is too small or too large, the soldering heat resistance and peel strength will be low.

Regarding the situation with silica-based fillers, if there is too much (A-15
) If the peel strength is too low (A-41)
Peel strength and flame retardancy decrease.

If there is too much l of iron oxide, it will peel off (A-17) 17
- Strength and surface resistance decrease, and if too low (A-16) flame retardancy decreases. In addition, for iron oxide with a ratio of 0 (A-
7) M: Flammability cannot be obtained.

Regarding (F) polysiloxane, even if it is too much,
Even if it is too small (A-11, A-14) peel strength,
Solder heat resistance decreases.

In A-1 to A-6, which are appropriate blending amounts, peel strength,
Good properties such as solder heat resistance and flame retardancy were obtained.

Example 2 A flexible printed wiring board (B-19) was obtained in the same manner as in Example 1, except that a polyamide-imide film (thickness: 5011 m) was used as the plastic film and A-1 was used as the adhesive. The performance of this product is shown in Table 2.

Example 3 Aluminum foil (thickness 50μ??L) was used as the metal foil,
A flexible printed wiring board (B-20
) was obtained.

18- The performance of this product is shown in Table 2.

-19- Special release +1. '7s8-21893 C8) type window Enter Lord Drive degree Ku Japan mutual

Claims (1)

[Claims] As a silicone adhesive, (A) 1' vinyl group bonded to a silicon atom in the molecule;
-Has an average of 2 or more, and an average degree of polymerization of 50 to 10,000
100 parts by weight of polyorganosiloxane, iB) A polyorganosiloxane having on average more than 2 hydrogen atoms bonded to silicon atoms in the molecule, the hydrogen atoms bonded to the silicon atoms in fAl. 0.5 to 10 moles per mole of vinyl group is also an amount; (C) 20 to 150 parts by weight of silica filler; +D)
Iron oxide or (and) 0.5 to 20 parts by weight of carbon black represented by the general formula (Fe0)x (Fe2O3)y (where zo is 0.05 to 1.0), (E) Platinum compound , 1-200 P as a platinum atom
Pm. (F) At least one hydrogen atom bonded to a silicon atom in the molecule, the general formula Q2 is a linear or branched alkylene group that is the same or different from each other, and R is an alkyl group having 1 to 4 carbon atoms. shows. ) and having at least one group bonded to a silicon atom in the molecule, an adhesive composition comprising 0.5 to 50 parts by weight of polysiloxane represented by
A method for producing a flexible printed wiring board, which comprises coating the plastic film or (and) metal foil as described above and drying the film, and then stacking the plastic film and the metal foil, heat-pressing them, and after-curing.