JP3529489B2 - Flux bleeding inhibitor for soldering - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-bleeding agent which prevents the flux applied to a printed board from spreading and wetting into the through hole during soldering of the printed board.

[0002]

2. Description of the Related Art Flux applied to a printed circuit board during soldering spreads out and spreads out from the applied part, or penetrates into a lead wire insertion hole or a through hole formed in the printed circuit board to face the opposite surface. May ooze out. If the flux comes out on the surface of the printed circuit board, it may adhere to electronic components such as switches and connectors mounted on the surface of the printed circuit board, resulting in poor conduction and corrosion of the lead wires of the components. Therefore, the printed circuit board after soldering is washed with a solvent such as CFC or trichlene.

However, although these solvents can easily remove the flux adhering to the printed circuit board, pollution problems such as destruction of the ozone layer and contamination of groundwater have been pointed out, and they have become unusable. Therefore, conventionally, a material for preventing the flux from seeping out on the surface of the printed circuit board has been proposed.

A material that prevents the conventional flux from seeping out on the surface of the printed circuit board (hereinafter simply referred to as a seepage preventing agent).
Is a solvent in which a fluorine-based surfactant or a silicon-based surfactant is dissolved (Japanese Patent Publication No. 4-16959, JP-A-60-).
No. 10694) and a fluororesin dissolved in a solvent (Japanese Examined Patent Publication No. 63-62315).

[0005]

By the way, an anti-bleeding agent using a surfactant has an effect of preventing flux from seeping up to the surface of a printed circuit board at the time of soldering. If the anti-bleeding agent remains on the printed circuit board surface, it may lower the insulation resistance,
There is a problem that a corrosion product is generated. The reason for this is that the surfactant has a function as a bleeding preventive agent for the soldering flux, but on the other hand, it has hygroscopicity, so that the surfactant remaining on the printed circuit board may not remain in the long term. This is because it absorbs moisture in the air to lower the insulation resistance of the printed circuit board or generate corrosion products.

The bleeding preventive agent in which a fluororesin is dissolved in a solvent does not have hygroscopicity like a surfactant, and therefore there is no problem due to moisture absorption. However, when the printed circuit boards are moved or stacked after coating, the bleeding preventing effect is obtained. Was sometimes reduced. This is because the fluororesin has a property of being easily peeled off after application. In other words, the printed circuit board may not be soldered immediately after applying the anti-bleeding agent and may wait for a while. At this time, if the printed boards rub against each other or the operator touches the application part, the applied anti-bleeding agent peels off, and the flux bleeds up to the part peeled off during soldering.

The present invention has been made in view of the drawbacks of conventional anti-bleeding agents, and provides an anti-bleeding agent which does not have hygroscopicity like a surfactant and does not easily peel off after application like a fluororesin. Especially.

[0008]

The present inventor completed the present invention by paying attention to the fact that certain acrylates have adhesiveness, water repellency and the like.

The invention of claim 1 is the component A: (meth) acrylic acid ester having 4 to 22 carbon atoms, and (meth) acrylic acid ester and / or (meth) acrylic acid having a reactive functional group, B Component: Saturated ester having a polyfluoroalkyl group or a polyfluoroether group having 4 to 21 carbon atoms and having a reactive functional group (provided that the total of the above components is 100% by weight). It is a coalesced, bleeding preventive agent for soldering that is dissolved and dispersed in an organic solvent.

The invention of claim 2 is the component A: (meth) acrylic acid ester having 4 to 22 carbon atoms, and (meth) acrylic acid ester and / or (meth) acrylic acid having a reactive functional group, B Component: Saturated ester having a reactive functional group having a C4-21 polyfluoroalkyl group or polyfluoroether group C Component: Having a C4-21 polyfluoroalkyl group or polyfluoroether group 5 unsaturated esters
It is a copolymer composed of less than 0% by weight (provided that the total of the above components is 100% by weight), which is a soldering bleeding inhibitor dissolved and dispersed in an organic solvent.

According to the third aspect of the invention, the component A is a (meth) acrylic acid ester having 4 to 22 carbon atoms, and a (meth) acrylic acid ester and / or (meth) acrylic acid having a reactive functional group. Component: Saturated ester D having a polyfunctional alkyl group or polyfluoroether group having 4 to 21 carbon atoms and having a reactive functional group D component: 15% by weight or less of a crosslinking agent (provided that the total of the above components is 100% by weight. A bleeding preventive agent for soldering, which is obtained by dissolving and dispersing in an organic solvent.

The invention of claim 4 is the component A: (meth) acrylic acid ester having 4 to 22 carbon atoms, and (meth) acrylic acid ester and / or (meth) acrylic acid having a reactive functional group, B Component: Saturated ester having a reactive functional group having a C4-21 polyfluoroalkyl group or polyfluoroether group C Component: Having a C4-21 polyfluoroalkyl group or polyfluoroether group 5 unsaturated esters
Less than 0% by weight, component D: cross-linking agent 15% by weight or less (provided that the total amount of the above components is 100% by weight), which is a copolymer dissolved and dispersed in an organic solvent. It is an anti-bleeding agent for attachment.

A fifth aspect of the present invention is the soldering bleeding preventive agent according to any one of the first to fourth aspects, which contains an acrylic macromonomer as the component A.

[0014]

The component A has a significant effect of imparting adhesiveness to the object to be coated, imparting a polymer film, imparting water repellency, expanding solvent selectivity, imparting polymer film-forming property, and the like. Is preferably present in at least 10% by weight. On the other hand, in order to effectively exert the bleeding preventing effect in the presence of the component A, the amount of the component A is preferably 80% by weight or less.

If the number of carbon atoms of the (meth) acrylic acid ester of the component A is less than 4, it has no tackiness and is easily peeled off when applied to a printed circuit board. Further, if the carbon number is larger than 22, it becomes difficult to dissolve in a solvent and cannot be applied to a printed circuit board. Therefore, in the present invention, a (meth) acrylic acid ester having 4 to 22 carbon atoms is used. The (meth) acrylic acid ester may be either a methacrylic acid ester or an acrylic acid ester, and the (meth) acrylic acid is
Either methacrylic acid or acrylic acid may be used.

Preferred specific examples of the (meth) acrylic acid ester having 4 to 22 carbon atoms as the component A include n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, amyl alcohol, hexanol, n-octanol and 2 ethylhexyl alcohol. , Nonanol,
Examples thereof include acrylic acid esters such as decanol, undecanol, lauryl alcohol, tridecanol, myristyl alcohol, pentadecanol, hexadecanol, heptadecanol, stearyl alcohol, nonadecanol, eicosanol, docosanol, and methacrylic acid esters. Two or more kinds of the (meth) acrylic acid ester having 4 to 22 carbon atoms may be used.

It is also possible to use compounds represented by the following general formula and styrene, vinyl acetate, acrylonitrile, butadiene and the like. _{^{CH 2 = CR 1 -COOR 2 ※}} R 1 = H or CH _3, R ² = an alkyl group having 1 to 22 carbon atoms, may be linear or branched

The (meth) acrylic acid or (meth) acrylic acid ester having a reactive functional group of the component A is as follows:
It refers to a (meth) acrylic acid ester-based monomer having a functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a glycidyl group, and a lower alkoxy group in the molecule. Specific preferred examples of the acrylic acid ester-based monomer having such a reactive functional group include (meth)
Acrylic acid, hydroxyethyl (meth) acrylate,
Examples thereof include glycidyl (meth) acrylate, N-methylol acrylamide, and dimethylamino (meth) acrylate. You may use 2 or more types of these. Further, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like can also be used.

As the component A, an acrylic macromonomer may be further included. The acrylic macromonomer is a high-molecular weight monomer having a copolymerizable functional group, and is composed of a trunk component to be copolymerized and a side chain (segment) branch component. The branch component is composed of (meth) acrylate having 18 or less carbon atoms, acrylonitrile, styrene, vinyl acetate, vinyl chloride, β-vinylnaphthalene, silicone, fluororesin, and the like, and further has a carboxyl group and a hydroxyl group at the terminal group. It is a high molecular weight monomer that can be added. As shown in FIG. 1, copolymerization with other low molecular weight monomers (acrylic acid ester, acrylonitrile, styrene, etc.) is easy, and a comb-type graft copolymer having a macromonomer as a branch portion can be obtained.
Therefore, a copolymer of a macromonomer and another low molecular weight monomer can impart the physical properties of the branch component while maintaining the physical properties of the trunk component, and thus it is difficult to achieve release / adhesion and hydrophilic / hydrophobic compatibility. It is possible to simultaneously exhibit the physical properties described. It is particularly effective when physical properties contradictory to each other are required as in the present invention.

The component B may include either a saturated ester having a polyfunctional alkyl group having 4 to 21 carbon atoms or a polyfluoroether group and a reactive functional group, or both of them. The reactive functional group may be a functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group and a glycidyl group.

The component B has a water-repellent and oil-repellent effect after the crosslinking reaction of the reactive functional group, and in order to exert such effect significantly, 20% by weight or more is present. Is preferred. On the other hand, if the component B is present at about 90% by weight at most, it is sufficient to exert the above-mentioned effects.

As the saturated ester having a polyfluoroalkyl group having 4 to 21 carbon atoms or a polyfluoroether group and a reactive functional group as the component B, the following can be exemplified.

[Chemical 1]

The flux bleeding preventive agent of the present invention has a sufficient flux bleeding prevention effect only with the components A and B, but when the component C is added in an amount of less than 50% by weight, the bleeding prevention effect can be more effectively exhibited. become. Component C is an unsaturated ester having a polyfluoroalkyl group or a polyfluoroether group having 4 to 21 carbon atoms.
When the content of these unsaturated esters is less than 50% by weight, the effect of preventing bleeding can be sufficiently exhibited, so the content was set to less than 50% by weight.

Examples of the unsaturated ester having a polyfluoroalkyl group having 4 to 21 carbon atoms include the following.

[Chemical 2]

Examples of the unsaturated ester having a polyfluoroether group having 4 to 21 carbon atoms include the following.

[Chemical 3]

When the cross-linking agent of the component D is added to the flux bleeding preventive agent of the present invention to cause a cross-linking reaction, the respective components of the component A, the component B, and the component C are combined, and the dispersion of each component of the bleeding preventive agent is The effect of preventing The preferable addition amount of the component D is 15% by weight or less.

As the cross-linking agent of the component D, a (meth) acrylic acid ester or (meth) acrylic acid having a reactive functional group of the component A and a polyfluoroalkyl group or a polyfluoroether group of the component B are reacted. A component that crosslinks the above-mentioned copolymer or reaction composition by reacting with a saturated ester having a polymerizable group, and preferable compounds include aziridine compounds, epoxy compounds, isocyanate compounds, aliphatic polyamine compounds, and alicyclic compounds. Group amine compounds, aromatic amine compounds, polyamide amine compounds, and the like. Addition of these cross-linking agents is not preferable because if it exceeds 15% by weight, the viscosity increases and gels to deteriorate the coating property.

The compounds of the crosslinking agent are exemplified below. Aziridine compounds

[Chemical 4]

Epoxy compounds vinylcyclohexene dioxide, dicyclopentadiene dioxide

Aromatic isocyanates such as isocyanate-based toluidine diisocyanate and methylene diisocyanate, and aliphatic isocyanates such as isophorone diisocyanate and hexamethylene diisocyanate

Aliphatic polyamine compounds diethylenetriamine, dipropylenetriamine, triethylenetriamine

Alicyclic amine compounds 3,3'-dimethyl 4,4'-diaminodicyclohexylmethane, isophoronediamine

Aromatic amine compounds 4,4'-diaminodiphenylmethane, phenylenediamine, toluylenediamine, xylyleneamine

Polyamidoamine compound Modified polyamidoamine, polyamide resin

Compounds other than those mentioned above Tertiary amines, imidazoles, acid anhydrides, metal chelates

The copolymer in the present invention is produced by the following production method. A-component and B-component copolymer, or A-component, B-component and D-component copolymer A-component (meth) acrylic acid ester, and a reactive functional group-containing acrylic acid ester and / or (meth (Acrylic acid), and optionally, an acrylic macromonomer is dissolved in an organic solvent, and then a catalyst is added to the solution.
Polymerization is performed according to a conventional method while heating and stirring at 0 ° C or lower. Next, the number of carbon atoms having the reactive functional group of the component B is 4 to 2
Saturated ester having a polyfluoroalkyl group or a polyfluoroether group of 1 is added and stirred, and A component and B
Reactively couple reactive functional groups of the components. If the A component and the B component are not directly reactively bonded depending on the selection of the reactive functional group, a crosslinking agent of the D component may be added to reactively bond the A component and the B component. A-component, B-component and C-component copolymer, or A-component, B-component, C-component and D-component copolymer A-component (meth) acrylic acid ester, and acrylic acid having a reactive functional group An ester and / or (methacrylic acid), and optionally, an acrylic macromonomer and an unsaturated ester monomer having a C component having a C4-21 polyfluoroalkyl group or a polyfluoroether group as an organic solvent. After being dissolved therein, a catalyst is added and polymerized by a conventional method while heating and stirring at 100 ° C. or lower. Next, a saturated ester having a polyfluoroalkyl group having 4 to 21 carbon atoms or a polyfluoroether group having a reactive functional group of the B component is added and stirred, and the B component is reactively bonded to the copolymer of the A component and the C component. Let When the reactive functional groups are not directly reactively bonded depending on the type, a cross-linking agent of component D can be added to obtain a copolymer of component A, component B, component C and component D.

The polymer thus copolymerized is
The solid content is 10 to 50% by weight. This copolymer is used by diluting it appropriately in an organic solvent according to the purpose of use.

The composition of the preferred monomer which is the component A is (meth) acrylic acid ester having the chemical formula CH ₂ ═CR ¹ COOR ² having ^{2 to} 4 carbon atoms in the R ² moiety, 5 to 30% by weight, and / or (meth). ) 5 to 30 wt% having a carbon number of 12 to 22 of the R ² moiety of the formula CH ^₂ = CR ¹ COOR ₂ acrylic acid ester, 5 to 30% by weight of acrylic acid esters having a reactive functional group, a. (Meth) acrylic ester having 4 to 12 carbon atoms
This is because those having the carbon number of 12 to 22 contribute to the development of the adhesiveness to the adherend, and those having the carbon number of 12 to 22 contribute to the development of the water repellency. The acrylic macromonomer is
Since it further contributes to the development of water repellency, it is more preferably included. This is because the acrylic acid ester having a reactive functional group successfully reacts with the reactive functional group of the B component.

The anti-bleeding agent of the present invention is used by dissolving the above components in an organic solvent. The organic solvent used here has a carbon number of 4 or less and a boiling point of 100 ° C. or less as exemplified later. Nonflammable hydrocarbon solvents are suitable. Further, it is one or more organic solvents selected from the group consisting of hydrocarbons having 5 to 10 carbon atoms, ethers having 1 to 6 carbon atoms, ketones having 1 to 6 carbon atoms and esters having 1 to 6 carbon atoms.

Examples of nonflammable hydrocarbon solvents having a carbon number of 4 or less and a boiling point of 100 ° C. or less include the following. Isopropyl bromide, methylene dibromide, bromochloromethane, n-propyl bromide, n-butyl bromide, isobutyl bromide, sec-butyl bromide, tert-butyl bromide, tert-butyl chloride, etc.

Examples of the hydrocarbon having 5 to 10 carbon atoms include the following. Benzene, toluene, xylene, ligroin, n-hexane, cyclohexane, heptane,
Examples of the ether having 1 to 6 carbon atoms such as pentane, octane, methylcyclohexane and cyclohexene include the following. Ethylene glycol monophenyl ether, diisopropyl ether, diethyl ether, dipropyl ether, dioxane, furan, 2-methylfuran, tetrahydrofuran, etc.

Examples of the ketone having 1 to 6 carbon atoms are as follows. Methyl ethyl ketone, holone, isophorone, diisobutyl ketone, methyl isobutyl ketone, acetone, etc.

The following can be exemplified as the ester having 1 to 6 carbon atoms. Ethyl formate, propyl formate, methyl formate, butyl formate, isobutyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, methyl propionate, ethyl propionate, methyl butyrate, etc.

[0044]

Examples and Comparative Examples Table 1 shows examples and comparative examples. A bleeding preventive agent was obtained by dissolving the copolymers of the present invention obtained in Examples 1 to 8 and the copolymers of Comparative Examples 1 to 2 in 1% by weight of methyl ethyl ketone. The solvent may be one or more mixed solvents selected from the group consisting of the above-mentioned organic solvents capable of dissolving or dispersing the copolymer of the present invention, and is not particularly limited to methyl ethyl ketone. Comparative Example 3 is an example in which the anti-bleeding agent is not used at all.

[0045]

[Table 1] (*) 2EHA: 2 ethylhexyl acrylate LaA: lauryl acrylate StA: stearyl acrylate (M) AA: (meth) acrylic acid HEMA: hydroxy (meth) acrylate DMAEMA: dimethylaminoethylmethacrylate AK-5: macro of polydimethylsiloxane methacrylate Monomer F · F: Polyfluoroalkyl saturated ester having carboxyl group or hydroxyl group FAC: Unsaturated ester having polyfluoroalkyl group TDI: Toluidine diisocyanate

A bleeding test, a peeling test and an insulation resistance test were carried out on the bleeding preventive agents of the above-mentioned Examples and Comparative Examples.

Bleeding Test First, the bleeding inhibitors of Examples and Comparative Examples were applied to the surface of the printed circuit board by a spray device, and left for 5 minutes to dry the bleeding inhibitors. Then, a flux is applied to the back surface of the printed board by a foam fluxer, the printed board is preheated to about 100 ° C. by a preheater, and then the back surface of the printed board is brought into contact with a jet solder bath at 230 ° C. for soldering. Observe the surface of the printed circuit board after soldering,
Check if flux is seeping out to the surface.

Peeling test Prepared are the bleeding inhibitors of the examples and comparative examples to which a small amount of red dye was added. The bleeding preventive agents of these Examples and Comparative Examples were applied to the surface of the printed circuit board with a spray device, and 5
Let stand for a minute to dry the anti-bleed agent. Then, the surface of the printed board is lightly rubbed with a cloth to observe the peeled state.

The printed circuit board used in the bleeding test of the insulation resistance test was allowed to stand in a constant temperature / humidity bath at a humidity of 90% and a temperature of 40 ° C. for 1000 hours, and then the insulation resistance of the printed circuit board was measured.

The bleeding preventive agent prevents bleeding of the flux from the back surface during soldering by applying it to the printed circuit board, but the bleeding preventive agent of the present invention can also be added to the solder paste. When the anti-bleeding agent of the present invention is added to the solder paste, the flux in the solder paste does not spread to an unnecessary portion during reflow, so that defects such as bridges and minute solder balls can be prevented.

Here, an example of a solder paste to which the anti-bleeding agent of the present invention is added will be shown. Polymerized rosin (pine resin) 55.5% by weight Castor wax (thixotropic agent) 1.5% by weight Diphenyl guanidine (activator) 1.0% by weight Saturated ester having polyfluoroalkyl group or polyfluoroether group 0.1% by weight % Ethylene glycol monophenyl ether 12% by weight flux consisting of the balance powder solder (63Sn
-Pb) 88% by weight was added to produce a solder paste. 2% by weight of the anti-bleeding agent produced in Example 1 was added to this to obtain a solder paste containing the anti-bleeding agent. A mask was placed on a printed circuit board, a solder paste containing an anti-bleeding agent was applied with a squeegee, and then electronic parts were mounted.
After that, it was passed through a reflow furnace for soldering.
Observation of the front and back surfaces of the printed circuit board after soldering revealed that no bridges or minute solder balls were generated.

[0052]

Since the anti-bleeding agent of the present invention does not absorb moisture even after a long time has passed after soldering, it does not lower the insulation resistance of the printed circuit board, and the coated part is touched or rubbed a little. The bleeding preventive agent adheres to the entire surface of the printed board at the time of soldering because it does not peel off as much as it does, and it is a highly reliable bleeding preventive agent that can completely prevent bleeding of the flux.

[Brief description of drawings]

FIG. 1 shows the formation of graft polymers by copolymerization of macromonomers with other monomers.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-201501 (JP, A) JP-A-6-112636 (JP, A) JP-A-62-54783 (JP, A) JP-A-61- 209213 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 3/34 B23K 1 / 00,3 / 00 C08F 2/44 C08F 220/18 C08F 220/24 C08F 290/06

Claims (5)

(57) [Claims] 1. Component A: a (meth) acrylic acid ester having 4 to 22 carbon atoms, and a (meth) having a reactive functional group.
Acrylic acid ester and / or (meth) acrylic acid, B component: Saturated ester having a reactive functional group having a polyfluoroalkyl group or a polyfluoroether group having 4 to 21 carbon atoms (however, the total of the above components is 100% by weight), a flux bleeding preventive agent for soldering, which is obtained by dissolving and dispersing in an organic solvent. 2. Component A: a (meth) acrylic acid ester having 4 to 22 carbon atoms, and a (meth) having a reactive functional group.
Acrylic ester and / or (meth) acrylic acid, B component: Saturated ester having a reactive functional group having a polyfluoroalkyl group or polyfluoroether group having 4 to 21 carbon atoms, C component: 4 carbon atoms The unsaturated ester having a polyfluoroalkyl group or a polyfluoroether group of 21 is 5
A flux bleeding preventive agent for soldering, which is a copolymer composed of less than 0% by weight (provided that the total of the above components is 100% by weight) and which is dissolved and dispersed in an organic solvent. 3. Component A: a (meth) acrylic acid ester having 4 to 22 carbon atoms, and a (meth) having a reactive functional group.
Acrylic acid ester and / or (meth) acrylic acid, B component: Saturated ester D component having a reactive functional group having a polyfluoroalkyl group or a polyfluoroether group having 4 to 21 carbon atoms, and D component: 15% by weight of a crosslinking agent % Or less (provided that the total of the above components is 100% by weight), which is a flux bleeding preventive agent for soldering, which is dissolved and dispersed in an organic solvent. 4. Component A: a (meth) acrylic acid ester having 4 to 22 carbon atoms and a (meth) having a reactive functional group.
Acrylic ester and / or (meth) acrylic acid, B component: Saturated ester having a reactive functional group having a polyfluoroalkyl group or polyfluoroether group having 4 to 21 carbon atoms, C component: 4 carbon atoms The unsaturated ester having a polyfluoroalkyl group or a polyfluoroether group of 21 is 5
Less than 0% by weight, component D: cross-linking agent 15% by weight or less (provided that the total amount of the above components is 100% by weight), which is a copolymer dissolved and dispersed in an organic solvent. Flux bleeding inhibitor for attachment. 5. The flux bleeding preventive agent for soldering according to any one of claims 1 to 4, further comprising a macromonomer as the component A.