JP2010111748A - Adhesive layer forming liquid and adhesive layer forming process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive layer forming liquid capable of easily maintaining the performance of forming an adhesive layer and ensuring adhesive property to a resin certainly, and to provide an adhesive layer forming process using the liquid. <P>SOLUTION: The adhesive layer forming liquid for forming the adhesive layer for bonding a copper and a resin to each other is an aqueous solution comprising an acid, a stannous salt, a stannic salt, a complexing agent, and a stabilizing agent, and is prepared to set the value of B/A to 0.010-1.000 on the preparation, wherein A represents the concentration (unit: mass%) of the stannous salt as the concentration of bivalent tin ions, and B represents the concentration (unit: mass%) of the stannic salt as the concentration of tetravalent tin ions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive layer forming liquid for forming an adhesive layer for bonding copper and a resin, and an adhesive layer forming method using the same.

  A general multilayer wiring board is manufactured by laminating and pressing an inner layer substrate having a conductive layer made of copper on the surface with another inner layer substrate or a copper foil with a prepreg interposed therebetween. The conductive layers are electrically connected by a through-hole called a through-hole whose hole wall is plated with copper. In order to improve the adhesion to the prepreg, a tin plating layer (adhesion layer) may be formed on the surface of the inner layer substrate with a tin plating solution described in Patent Literatures 1 and 2 below.

However, since the tin plating solutions described in Patent Documents 1 and 2 use a stannous salt as a tin source, divalent tin ions (Sn ²⁺ ) are converted into tetravalent tin ions (Sn ⁴⁺ ) by air oxidation during use. There is a problem that the plating adhesion is lowered and the adhesion with the resin is lowered.

  In order to solve the above problem, Patent Documents 3 and 4 below propose a method of regenerating tetravalent tin ions into divalent tin ions using metallic tin.

Japanese Examined Patent Publication No. 6-66553 Special table 2004-536220 gazette JP-A-5-222540 Japanese Patent Laid-Open No. 5-263258

  However, in the methods of Patent Documents 3 and 4, it is difficult to adjust the components in the tin plating solution, and the practicality is poor.

  The present invention has been made in view of the above circumstances, and an adhesive layer forming liquid capable of easily maintaining the adhesive layer forming performance and ensuring adhesion with a resin, and an adhesive layer forming method using the same. provide.

The adhesive layer forming liquid of the present invention is an adhesive layer forming liquid for forming an adhesive layer for bonding copper and a resin,
An aqueous solution comprising an acid, stannous salt, stannic salt, complexing agent, and stabilizer;
At the time of preparation, when the concentration of the stannous salt was A mass% as the concentration of divalent tin ions and the concentration of the stannic salt was B mass% as the concentration of tetravalent tin ions, the value of B / A It was prepared so that it might become 0.010 or more and 1.000 or less.

The adhesive layer forming method of the present invention is an adhesive layer forming method for forming an adhesive layer for bonding copper and a resin,
It includes a step of treating the copper surface with the adhesive layer forming liquid of the present invention.

  In addition, the “copper” in the present invention may be made of pure copper or a copper alloy. In this specification, “copper” refers to pure copper or a copper alloy.

  According to the adhesive layer forming liquid of the present invention and the adhesive layer forming method using the same, the formation performance of the adhesive layer can be easily maintained, and the adhesion to the resin can be ensured.

  The present invention is directed to an adhesive layer forming liquid for forming an adhesive layer mainly composed of a copper-tin alloy on a copper surface in order to bond copper and a resin, and an adhesive layer forming method using the same. Examples of the copper surface include the surface of copper foil (electrolytic copper foil, rolled copper foil) used for electronic parts such as semiconductor wafers, electronic substrates, lead frames, ornaments, and building materials, and copper plating films (nothing). Examples thereof include the surface of an electrolytic copper plating film and an electrolytic copper plating film), or the surface of a copper material for various uses such as a linear shape, a rod shape, a tubular shape, and a plate shape. Hereinafter, the components contained in the adhesive layer forming liquid of the present invention will be described.

(acid)
The acid contained in the adhesive layer forming liquid of the present invention functions as a pH adjuster and a tin ion stabilizer. Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, borofluoric acid, and phosphoric acid, carboxylic acids such as formic acid, acetic acid, propionic acid, and butyric acid, alkanesulfonic acids such as methanesulfonic acid and ethanesulfonic acid, Examples thereof include water-soluble organic acids such as aromatic sulfonic acids such as benzenesulfonic acid, phenolsulfonic acid, and cresolsulfonic acid. Of these, sulfuric acid and hydrochloric acid are preferable from the viewpoint of the formation rate of the adhesive layer and the solubility of the stannic salt. A preferable concentration of the acid is 1 to 50% by mass, more preferably 3 to 30% by mass, and still more preferably 5 to 20% by mass. If it is in the said range, the contact bonding layer excellent in adhesiveness can be formed easily.

(Stannous salt)
In the present invention, stannous salt is used as a tin source. Examples of stannous salts include stannous sulfate, stannous borofluoride, stannous fluoride, stannous nitrate, stannous oxide, stannous chloride, stannous formate, and stannous acetate. It can be illustrated. The preferable concentration of the stannous salt is in the range of 0.05 to 10.00% by mass as the concentration of divalent tin ions, more preferably in the range of 0.10 to 5.00% by mass, and still more preferably 0. The range is from 50 to 3.00 mass%. If it is in the said range, the contact bonding layer excellent in adhesiveness can be formed easily.

(Stannic salt)
In the adhesive layer forming liquid of the present invention, a stannic salt is added in addition to the stannous salt at the time of preparation. Thereby, even when it uses continuously, it can suppress that the bivalent tin ion in a contact bonding layer formation liquid is oxidized to a tetravalent tin ion by air oxidation etc. As the stannic salt, any stannic salt that is soluble in an acidic solution can be used without particular limitation, but salts with the acid are preferable from the viewpoint of solubility. Examples thereof include stannic sulfate, stannic fluoride, stannic nitrate, stannic chloride, stannic formate, and stannic acetate. A preferable concentration of the stannic salt is in a range of 0.01 to 5.00% by mass, more preferably in a range of 0.01 to 1.50% by mass as a concentration of tetravalent tin ions. If it is in the said range, the contact bonding layer excellent in adhesiveness can be formed easily.

  In the preparation of the adhesive layer forming liquid of the present invention, the concentration of the stannous salt is A mass% as the concentration of divalent tin ions, and the concentration of the stannic salt is B mass% as the concentration of tetravalent tin ions. The B / A value is adjusted to 0.010 or more and 1.000 or less. Here, "at the time of preparation" refers to the time of blending when the components constituting the adhesive layer forming liquid are blended, specifically, when blending the stannous salt and the stannic salt Point to. By setting the value of B / A to 0.010 or more during the preparation of the adhesive layer forming liquid, the formation performance of the adhesive layer can be easily maintained even when continuously used. Moreover, adhesiveness with resin is securable by making the value of B / A into 1.000 or less at the time of preparation of an adhesive layer formation liquid. In order to exhibit the above effect more effectively, it is preferable to prepare so that the value of B / A at the time of preparation of the adhesive layer forming liquid is 0.050 or more and 0.500 or less.

(Complexing agent)
The complexing agent contained in the adhesive layer forming liquid of the present invention coordinates to the underlying copper surface to form a chelate and facilitates formation of the adhesive layer on the copper surface. For example, thioureas such as thiourea, 1,3-dimethylthiourea, 1,3-diethyl-2-thiourea, and thiourea derivatives such as thioglycolic acid can be used. A preferable concentration of the complexing agent is in the range of 1 to 30% by mass, and more preferably in the range of 1 to 20% by mass. Within this range, an adhesive layer having excellent adhesion can be formed without reducing the formation speed of the adhesive layer. Moreover, if it exists in this range, an adhesive layer with favorable smoothness can be formed.

(Stabilizer)
The stabilizer contained in the adhesive layer forming liquid of the present invention is an additive for maintaining the concentration of each component necessary for the reaction in the vicinity of the copper surface. Examples of the stabilizer include glycols such as ethylene glycol, diethylene glycol, propylene glycol, and tripropylene glycol, and glycol esters such as cellosolve, carbitol, and butyl carbitol. A preferable concentration of the stabilizer is in the range of 1 to 80% by mass, more preferably 5 to 80% by mass, and still more preferably 10 to 80% by mass. If it is in the said range, the density | concentration of each component required for reaction can be easily maintained in the vicinity of the copper surface.

  In addition to the above components, a reducing agent such as hypophosphorous acid, a brightener, a pH adjuster, a preservative and the like can be appropriately added to the adhesive layer forming liquid of the present invention as necessary. The content of these additive components is, for example, about 0.1 to 20% by mass.

  The adhesive layer forming liquid of the present invention can be easily prepared by dissolving each of the above components in water. As the water, water from which ionic substances and impurities have been removed is preferable. For example, ion exchange water, pure water, ultrapure water, and the like are preferable.

  When forming an adhesive layer using the adhesive layer forming liquid of the present invention, for example, it can be formed under the following conditions.

  First, the copper surface is washed with an acid or the like. Next, the copper surface is immersed in the adhesive layer forming liquid, and a rocking immersion treatment is performed for 5 seconds to 5 minutes. The temperature of the adhesive layer forming liquid at this time may be about 20 to 70 ° C. (preferably 20 to 40 ° C.). Then, an adhesive layer (tin plating layer) is formed by washing with water and drying.

  Further, the surface of the adhesive layer may be treated with a tin stripping solution. This is because a smoother and thinner adhesive layer can be formed by bringing the tin stripping solution into contact with the surface of the adhesive layer.

  The tin stripping solution may be any solution that can etch tin. For example, an acidic solution such as a nitric acid aqueous solution, hydrochloric acid, a sulfuric acid aqueous solution, or a mixed solution thereof can be used. The acid concentration of the acidic solution is preferably in the range of 0.1 to 10% by mass, and more preferably in the range of 0.3 to 5% by mass. Within this range, the thickness of the adhesive layer can be easily controlled within an appropriate range. In particular, an aqueous nitric acid solution is preferable because of its high peeling rate. In addition, you may add other additives, such as surfactant and a pH adjuster, to a tin stripping solution.

  In the surface peeling step, the contact time between the adhesive layer surface and the tin peeling solution (preferably nitric acid aqueous solution) is preferably 5 to 120 seconds, more preferably 10 to 30 seconds. Within this range, the thickness of the adhesive layer can be easily controlled within an appropriate range. As a method of bringing the tin stripping solution into contact, a liquid contact processing method such as immersion or spraying can be employed. In this case, the temperature of the tin stripping solution is about 25 to 35 ° C.

  The appropriate thickness of the adhesive layer is 0.02 μm or less, preferably 0.001 to 0.02 μm, and more preferably 0.003 to 0.02 μm. When the thickness of the adhesive layer is 0.001 μm or more, the adhesiveness with the resin layer can be easily secured. On the other hand, when the thickness of the adhesive layer is 0.02 μm or less, the adhesive layer can be easily removed when it is necessary to remove the adhesive layer in a later step.

  The resin constituting the resin layer to be bonded to the adhesive layer is not particularly limited, but acrylonitrile / styrene copolymer resin (AS resin), acrylonitrile / butadiene / styrene copolymer resin (ABS resin), fluororesin, polyamide, polyethylene, polyethylene Thermoplastic resins such as terephthalate, polyvinylidene chloride, polyvinyl chloride, polycarbonate, polystyrene, polysulfone, polypropylene, liquid crystal polymer, epoxy resin, phenol resin, polyimide, polyurethane, bismaleimide / triazine resin, modified polyphenylene ether, cyanate ester, etc. And UV curable resins such as UV curable epoxy resins and UV curable acrylic resins. These resins may be modified with functional groups, and may be reinforced with glass fibers, aramid fibers, other fibers, and the like.

  The adhesive layer obtained by the present invention has an adhesive property with insulating resin, etching resist, solder resist, conductive resin, conductive paste, conductive adhesive, dielectric resin, hole filling resin, flexible coverlay film, etc. It can be secured. Therefore, according to this invention, since the adhesiveness of a copper layer and a resin layer is securable, a reliable wiring board can be provided, for example.

  Next, examples of the present invention will be described together with comparative examples. In addition, this invention is limited to a following example and is not interpreted.

(Treatment with new solution)
One liter of an adhesive layer forming solution (temperature: 30 ° C.) having the composition shown in Table 1 below was prepared. In any adhesive layer forming liquid, the remainder excluding the components shown in Table 1 was ion-exchanged water. Then, an electrolytic copper foil (3EC-III made by Mitsui Mining & Smelting Co., Ltd., thickness 35 μm) cut to 100 mm × 100 mm as a test piece is prepared, and this test piece is put into each of the above solutions (new solutions) one by one. A rocking immersion treatment for 30 seconds was performed. Thereafter, the treated test piece was washed with water and immediately subjected to a rocking immersion treatment with a 0.7 mass% nitric acid aqueous solution (temperature: 30 ° C.) for 20 seconds, followed by washing with water and drying treatment.

(Treatment with old liquid)
Separately from the above, prepare 1 liter of an adhesive layer forming solution (temperature: 30 ° C.) having the composition shown in Table 1 below, and stir each solution under the same conditions as above. 500 sheets were continuously processed over 24 hours. Next, one test piece similar to the above was put into each of the treated liquids (old liquid) one by one and processed under the same conditions as described above. Thereafter, the treated test piece was washed with water and immediately subjected to a rocking immersion treatment with a 0.7 mass% nitric acid aqueous solution (temperature: 30 ° C.) for 20 seconds, followed by washing with water and drying treatment.

(Adhesion)
Each test piece after the treatment was sampled, and a photosensitive liquid solder resist (SR-7200, manufactured by Hitachi Chemical Co., Ltd.) was applied to the thickness of about 20 μm through the adhesive layer and cured. Thereafter, peel strength (N / mm) was measured in accordance with JIS C 6471. The results are shown in Table 1.

(Tin plating adhesion)
500 sheets of the new adhesive layer forming liquid (temperature: 30 ° C.) having the composition shown in Table 1 below and the adhesive layer forming liquid having the composition shown in Table 1 are processed for 24 hours under the same conditions as described above. The continued old liquid (temperature: 30 ° C.) was prepared 1 liter at a time. Then, an electrolytic copper foil (3EC-III made by Mitsui Mining & Smelting Co., Ltd., thickness 35 μm) cut into 100 mm × 100 mm is prepared as a test piece, and this test piece is put in each of the above solutions (new solution and old solution) one by one. Put the plating in less than 3 seconds in the appearance observation, mark the one with plating in 3 to 10 seconds, and mark the one without plating within 10 seconds as x. (Adhesive layer formation performance) was evaluated.

  As shown in Table 1, in Examples 1 to 11 of the present invention, better results were obtained for both peel strength (adhesion) and tin plating adhesion than Comparative Examples 1 to 4.

(Inhibition effect of Sn ²⁺ air oxidation by addition of Sn ⁴⁺ )
In order to confirm that the air oxidation of Sn ²⁺ is suppressed by adding Sn ⁴⁺ to the adhesive layer forming solution in advance, the following experiment was performed.

  1 liter of an adhesive layer forming liquid having the same composition as Comparative Example 4 in Table 1 was prepared, and this liquid was stirred at a temperature of 30 ° C. for 2 hours without any treatment of the test piece. A layer forming liquid (new liquid) was used. The concentration of each component of Comparative Example 5 was the same as that of the new solution of Example 4 in Table 1. Then, an electrolytic copper foil (3EC-III manufactured by Mitsui Kinzoku Mining Co., Ltd., thickness 35 μm) cut into 100 mm × 100 mm was prepared as a test piece, and this test piece was placed in the new solution of Comparative Example 5 above for 30 seconds. A rocking immersion treatment was performed. Thereafter, the treated test piece was washed with water and immediately subjected to a rocking immersion treatment with a 0.7 mass% nitric acid aqueous solution (temperature: 30 ° C.) for 20 seconds, followed by washing with water and drying treatment.

  Separately from the above, 1 liter of the new liquid of Comparative Example 5 described above was prepared, and 500 test pieces similar to those described above were continuously processed over 24 hours under the same conditions as above while stirring the liquid. Subsequently, the test piece similar to the above was put in the liquid after treatment (the old liquid), and the treatment was performed under the same conditions as described above. Thereafter, the treated test piece was washed with water and immediately subjected to a rocking immersion treatment with a 0.7 mass% nitric acid aqueous solution (temperature: 30 ° C.) for 20 seconds, followed by washing with water and drying treatment.

  About each test piece after a process, adhesiveness evaluation was performed similarly to the above. Moreover, the tin plating adhesiveness of each of the new solution and the old solution of Comparative Example 5 was evaluated in the same manner as described above. About these evaluation results, it shows in Table 2 with the result of Example 4 mentioned above.

As shown in Table 2, in Example 4 was added in advance ^{Sn 4+,} concentration decreases due to air oxidation of ^{Sn 2+} is ^suppressed, the change in the value of Sn 4+ / ^{Sn 2+} (i.e. the value of B / A) is also suppressed I understand that Thereby, evaluation of adhesiveness and tin plating adhesiveness was favorable about both a new liquid and an old liquid. On the other hand, the comparative example 5 containing ^{Sn 4+} produced by air oxidation of ^{Sn 2+,} (increasing concentrations of ^{Sn 4+)} density losses due to air oxidation of ^{Sn 2+} was observed remarkably. As a result, both the adhesion and tin plating adhesion of the old solution of Comparative Example 5 were deteriorated. From this result, when Sn ⁴⁺ is added to the adhesive layer forming liquid in advance, an effect of preventing the deterioration of the adhesive layer forming liquid can be obtained. However, in Sn ⁴⁺ generated by air oxidation of Sn ²⁺ , the adhesive layer forming liquid is deteriorated. It can be seen that the prevention effect cannot be obtained.

Claims (8)

An adhesive layer forming liquid for forming an adhesive layer for bonding copper and resin,
An aqueous solution comprising an acid, stannous salt, stannic salt, complexing agent, and stabilizer;
At the time of preparation, when the concentration of the stannous salt was A mass% as the concentration of divalent tin ions and the concentration of the stannic salt was B mass% as the concentration of tetravalent tin ions, the value of B / A Is an adhesive layer forming liquid prepared so that the ratio is 0.010 or more and 1.000 or less. Said A is 0.05-10.00,
The adhesive layer forming liquid according to claim 1, wherein B is 0.01 to 5.00.   The adhesive layer forming liquid according to claim 1, wherein the complexing agent is at least one selected from thioureas and thiourea derivatives.   The adhesive layer forming liquid according to claim 1, wherein the stabilizer is at least one selected from glycols and glycol esters. An adhesive layer forming method for forming an adhesive layer for bonding copper and resin,
A method for forming an adhesive layer, comprising a step of treating a copper surface with the adhesive layer forming liquid according to claim 1.   The adhesive layer forming method according to claim 5, wherein the step of treating the copper surface is a step of immersing the copper surface in the adhesive layer forming liquid.   The method for forming an adhesive layer according to claim 5 or 6, further comprising a step of treating the surface of the obtained adhesive layer with a tin stripper after the step of treating the copper surface.   The method for forming an adhesive layer according to claim 7, wherein the tin stripping solution is a nitric acid aqueous solution.