JPH02127966A - Inhibitor for crawling-up of flux - Google Patents

Abstract

PURPOSE:To enhance the heat resistance and to smoothly and advantageously prevent crawling-up of a flux by adopting a polymer having a fluorine contained aliphatic ring structure. CONSTITUTION:A polymer having fluorine contained aliphatic ring structure is used as a flux crawling-up inhibitor. When this polymer is applied to a printed board, etc., by melting with a solvent, it can be prevented that a flux crawls up from a through-hole, etc., and intrudes into parts from a lead wire part of electronic parts at the time of a soldering work. Especially, even under a high temperature at the time of soldering, a flux crawling-up preventive effect is displayed. This polymer can be obtained smoothly and advantageously by cyclic polymerization.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for soldering printed circuit boards, etc., in which flux creeps up from through holes etc. and enters the parts through the lead wires of electronic parts, causing damage to the parts. This invention relates to a novel flux creep-up inhibitor that can prevent damage to the flux.

[Prior Art] Conventionally, as a method for preventing flux creep-up, it has been known to apply a polymer compound having a perfluoroalkyl group as disclosed in JP-A-60-49859. This is because the low surface energy of the perfluoroalkyl group repels the flux, thereby preventing the flux from rising inside the through hole due to capillary action. However, this method was not perfect because the low surface energy properties of the perfluoroalkyl group deteriorated due to the high heat during soldering.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a flux creep-up inhibitor with high heat resistance.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and provides a novel flux creep-up inhibitor characterized by comprising a polymer having a fluorine-containing aliphatic ring structure. It is related to.

In the present invention, a polymer having a fluorine-containing aliphatic ring structure as detailed below is usually dissolved in a solvent, and this solution is applied to a printed circuit board, etc., thereby smoothly and advantageously preventing flux from creeping up. It is.

In the present invention, the polymer having a fluorine-containing aliphatic ring structure may be exemplified over a wide range of examples, including those that are conventionally known or well-known. Therefore, in the present invention, a fluorine-containing polymer having the above-mentioned specific ring structure in the main chain is preferably employed.

Examples include those having a ring structure as shown in the general formula. Among these,
Polymers having the following ring structures are typical. However, the content of the present invention is not limited to these only.

C.F.

C.F.

FCI C.F.

C.F.

CF3 The manufacturing method of these polymers is as follows: In the following two ways be.

however, Limited to these manufacturing methods isn't it.

1.Those using cyclopolymerization (USP 3418303°B, etc.) (USP, etc.) 2.Those using cyclic monomers (USP) In the above, polymers having a perfluoroaliphatic ring structure were exemplified, but in the present invention, Examples include those in which part of the fluorine atoms listed above are substituted with other hydrogen atoms or organic groups, or those having a ring structure such as that obtained by metathesis polymerization.

Therefore, the polymer having a specific ring structure in the present invention can be obtained smoothly and advantageously by the above-mentioned cyclization polymerization, but
In particular, by using a monomer that has two polymerizable groups with different polymerizability in the molecule and in which the number of atoms in the linear part of the connecting chain connecting these two polymerizable groups is 2 to 7,
Even if ultra-high pressure conditions or large dilution conditions are not employed, the cyclization polymerization can proceed smoothly and advantageously by suppressing gelation by-products.

As a monomer suitable for the above-mentioned cyclization polymerization, first of all, it is desirable that the monomer has two carbon-carbon multiple bonds having different polymerizability. Usually, a carbon-carbon double bond is used, and two multiple bonds of different types or structures are used. For example, a fluorine-containing monomer with two non-symmetrical multiple bonds, a vinyl group and an allyl group, a vinyl ether group and a vinyl group, a fluorine-containing multiple bond and a hydrocarbon multiple bond, a perfluorinated multiple bond and a partially fluorinated multiple bond. Examples include: Secondly, it is desirable that the number of atoms in the linear portion of the connecting chain connecting these two carbon-carbon multiple bonds is 2 to 7. The number of atoms in the straight chain part of the connected chain is 0~
When there is only one, cyclization polymerization is difficult to occur, and the same holds true when there are eight or more. Usually, preferably, this number of atoms is 2.
This is the case of ~5 pieces. Furthermore, the connecting chain is not limited to a straight chain, and may have a side chain structure or a ring structure (furthermore, the constituent atoms are not limited to carbon atoms, but may include heteroatoms such as O, S, and N). Also good.Thirdly, the fluorine content is 1
A content of 0% by weight or more is desirable. If the fluorine content is too low, the specificity of fluorine atoms will be difficult to exhibit. Naturally, perfluoromonomers are preferably employed.

Specific examples of the above specific fluorine-containing monomer include CF2=CFOCF2CF=CF2. CF2=CF
OCF2CF, CF=CFt.

CF2. CFOCF2CF=CH,.

CF, =CFOCF2(CH2), NHCCH=CH2
(However, X is an integer from 1 to 4).

しt"Lt'z しt'2-shit'2 CF3 CF2"CHOCH2CH2CF"CF2.CHx"C
FCOCHzCH2CF”CFz.

C.F.

CH2=CC0CH2CH2CF=CF2. CH□
=CHOCH2CH2CF2CF=CF2, etc. may be exemplified. In the present invention, those having one vinyl ether group such as CF2=CFO- are preferably employed in terms of polymerization reactivity, cyclopolymerizability, gelation suppression, etc., and in particular, perfluoroallyl vinyl ether (CF, =CFOCF2
Suitable examples include CF=CF2) and perfluorobutenyl vinyl ether (CF, =CFOCF2CF2CF=CF!).

The above monomer components may be used alone or in combination of two or more, and there is no problem in copolymerizing them in combination with other copolymerization components to the extent that the essence of these components is not impaired. If necessary, the polymer may be crosslinked in some way.

Other monomers to be copolymerized are not particularly limited as long as they are radically polymerizable monomers, and include a wide range of fluorine-containing monomers, hydrocarbon monomers, and others.

Of course, these other monomers may be used alone in radical copolymerization with a monomer capable of introducing the specific ring structure, or two or more appropriate types may be used in combination in the above copolymerization reaction. You may also have them do this.

In the present invention, it is usually desirable to select fluorine-containing monomers such as fluoroolefins and fluorovinylethers as other monomers. For example, preferred examples include tetrafluoroethylene, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, and perfluorovinyl ether containing a functional group such as a carboxylic acid group or a sulfonic acid group. , chlorotrifluoroethylene, etc. may also be exemplified.

As for the copolymer composition, in order to take advantage of the characteristics of the specific fluorine-containing aliphatic ring structure aimed at in the present invention, the composition of the cyclic structure is preferably 20% or more, and more preferably 4% or more.
It is desirable that it is 0% or more.

In the present invention, as a method for crosslinking the fluorine-containing polymer, commonly used methods can be used as appropriate. For example, crosslinking can be achieved by copolymerizing a monomer having a crosslinking site, by adding a crosslinking agent, or by using radiation.

Furthermore, various additives such as antioxidants and ultraviolet stabilizers may be added to the fluoropolymer of the present invention in order to improve its practicality.

Since the polymer having a specific ring structure in the present invention is soluble in fluorine-based solvents, flux creep-up can be prevented by coating from a solution.

Furthermore, since the thermoplastic resin has a low melting temperature and a relatively low melt viscosity, it is also possible to perform hot melt molding.

The solvent to be used is not limited as long as it dissolves the above polymer, but examples include perfluorobenzene, "Afluid" (trade name: fluorinated solvent manufactured by Asahi Glass Co., Ltd.), and "Fluorinert" (trade name: manufactured by 3M Company). Perfluoro (2
-butyltetrahydrofuran), trichlorotrifluoroethane, and the like are suitable. As a matter of course, two or more appropriate types can be used in combination as a solvent. Particularly in the case of a mixed solvent, hydrocarbons, chlorinated hydrocarbons, fluorochlorinated hydrocarbons, alcohols, and other organic solvents can also be used in combination. Solution concentration is 0.01wt%~50w
t%, preferably O, 1wt% to 20wt%.

[Function] In the present invention, the polymer having a fluorine-containing aliphatic ring structure can be imparted with low surface energy properties due to the presence of fluorine-containing groups such as (cpz) groups, so it repels liquids such as flux, and Flux can be prevented from creeping up through the pores. Further, the polymer having the specific structure of the present invention can have a softening temperature as high as, for example, 106° C., and can maintain low surface energy properties even at high temperatures when soldered. Furthermore, based on the specific fluorine-containing aliphatic ring structure, it is soluble in fluorine-based solvents, etc.
A suitable solution can be prepared and easily applied to printed circuit boards and the like.

[Examples] Next, Examples of the present invention will be described in more detail, but it goes without saying that this description does not limit the present invention.

Synthesis Example 1 35 g of perfluoroallyl vinyl ether, 5 g of trichlorotrifluoroethane (hereinafter abbreviated as R-113), 150 g of ion exchange water, and 35 mg of (C, F, Go) 2 as a polymerization initiator, Internal volume 200m
It was placed in a pressure-resistant glass autoclave. After purging the system with nitrogen three times, it was kept at 26°C for 23 hours! I! ! , turbidity polymerization was performed. As a result, 28 g of polymer was obtained.

When we measured the infrared absorption spectrum of this polymer, we found that
1660 cm-' due to the double bond in the monomer
, there was no absorption near 1840 cm-'.

In addition, this polymer was dissolved in perfluorobenzene and II
When the NMR spectrum of IF was measured, a spectrum showing the following repeating structure was obtained.
A liquid whose main component is perfluoro(2-butyltetrahydrofuran) manufactured by Company M, hereinafter abbreviated as FC-75)
It was 0.530 at 30°C. The glass transition point of the polymer is 69°C, and it is a tough, transparent glass-like polymer at room temperature. The 1O% thermal decomposition temperature was 462°C, and the polymer was colorless and transparent, had a low refractive index of 1.34, and a high light transmittance of 95%.

Synthesis Example 2 20 g of 1,1.2.4.4.5.5-hebutafluoro-3-oxa-1,6-hebutadiene and 40 g of R-113 were placed in a nitrogen-substituted Mitsuro flask, and during polymerization After adding 20 mg of (C3F?GO)2 as an initiator and purging the system with nitrogen, polymerization was carried out at 18° C. for 10 hours.

As a result, 10 g of polymer was obtained. This polymer is R-11
The intrinsic viscosity [η] at 30° C. in meta-xylene hexafluoride was 0.96. It was confirmed by F NMR and 'H NMR that it was a polymer having a cyclic structure in its main chain.

Additionally, this polymer is colorless and transparent, and has a refractive index of 1.36.
The light transmittance was as high as 93%.

Synthesis example 3 35 g of perfluorobutenyl vinyl ether.

150 g of ion-exchanged water, and as a polymerization initiator (C,
F, Go)! 70 mg of the sample was placed in a pressure-resistant glass autoclave with an internal volume of 200 m1. After purging the system with nitrogen three times, suspension polymerization was carried out at 25° C. for 48 hours. As a result, 21 g of polymer was obtained. 3 in FC-75 of this polymer
The intrinsic viscosity at 0°C was 0.35.

The glass transition point of the polymer was 106°C, the refractive index was 1.34°, and the light transmittance was 95%.

Synthesis Example 4 21g and R of CFa=cFcF2cF, cH=cF2
38 g of -113 was placed in a nitrogen-substituted Mitsuro flask, 15B (C3F, Co) was added as a polymerization initiator, and the system was further substituted with nitrogen, followed by polymerization at 20° C. for 12 hours.

As a result, 14 g of polymer was obtained. This polymer is a polymer that dissolves in tetrahydrofuran (hereinafter abbreviated as THF), and the intrinsic viscosity [η] at 30°C in THF is 0.
It was 62.

Examples and Comparative Examples A solution is prepared by dissolving 2% of the polymer of the present invention (Example) and perfluoroacrylate homopolymer (Comparative Example) obtained in Synthesis Examples 1 to 4 in Freon R-113. The above solution was applied to a glass epoxy substrate and dried at room temperature for 10 minutes to form a thin film of the polymer of the present invention on the substrate. In addition, as another comparative example, an uncoated substrate was prepared.

Isopropyl alcohol (IPA,
A flux solvent) was applied at 1 μ°C and the contact angle was measured. Next, the substrate was heated to 50° C. and similar measurements were performed. These results are shown in Table 1 below.

Table 1 * Soldering was determined by visual inspection to prevent flux creeping up afterward, and those with no creeping up through the through hole were considered good.Those with - part creeping up were judged as slightly inferior. .

[Effects of the Invention] The present invention has an excellent effect in that flux creep-up can be smoothly and advantageously prevented by employing a polymer having a fluorine-containing aliphatic ring structure as a material. In particular, it has the effect of preventing flux from creeping up even under high temperatures during soldering. Furthermore, the present invention has the advantage that it can be used as an inhibitor with good coating workability due to the characteristics of the material.

Claims (1)

[Claims] (1) A flux creep-up preventive agent comprising a polymer having a fluorine-containing aliphatic ring structure.