WO2005085498A1

WO2005085498A1 - Metal surface treating agent

Info

Publication number: WO2005085498A1
Application number: PCT/JP2005/002813
Authority: WO
Inventors: Takashi Ouchi
Original assignee: Nippon Mining & Metals Co., Ltd.
Priority date: 2004-03-05
Filing date: 2005-02-22
Publication date: 2005-09-15
Also published as: CN1930323B; CN1930323A; TWI301515B; TW200533783A; KR100802878B1; JP4518507B2; JPWO2005085498A1; CN102424965A; KR20060122967A

Abstract

Disclosed is a surface treating agent for imparting a metal, in particular an Sn and Sn alloy plating, with oxidation resistance and improving the solder wettability thereof. Also disclosed is a surface treating agent for suppressing generation of whiskers in the Sn and Sn alloy plating. The metal surface treating agent is characterized by containing one or more substances selected from compounds having two or more phosphonic acid groups and no ester bond in one molecule and/or salts thereof in an amount of not less than 0.01 g/L in total. It is preferable that the surface treating agent has a pH of not more than 5 and further contains 0.1-10 g/L of a surfactant. Metals preferably treated by this surface treating agent are Sn and Sn alloys.

Description

Specification

Metal surface treatment agent

Technical field

The present invention relates to a surface treatment agent for metals, particularly Sn and Sn alloys, and a surface treatment method using the same. Furthermore, the present invention provides an electronic component, a substrate, a solder ball, a solder powder, a ball grid array using the solder ball, a solder paste using the solder powder, a solder paste using the solder powder, and the like. Related mounting products. Background art

[0002] Soldering is a technique for joining objects using a substance having a relatively low melting point, and is widely used in modern industry for joining and assembling electronic devices. The commonly used solder is Sn-Pb alloy, and its eutectic composition (63% Sn-balance Pb) has a low melting point of 183 ° C. Since it is performed in C, it hardly causes thermal damage to electronic components and substrates. In addition, the Sn-Pb alloy has excellent solderability, and also has the excellent characteristics that it solidifies immediately upon soldering and does not easily crack or peel even when vibration is applied to the soldered part. ing.

[0003] Generally, electronic devices are formed of a synthetic resin such as an outer frame or a board and a metal such as a conductor or a frame. When disposed, they are not incinerated and are mostly buried in the ground. Can be In recent years, rain falling on the ground tends to be acidic (acid rain), and contaminating groundwater by eluting solder for electronic devices buried underground has become a problem. For this reason, the use of lead-free solder (lead-free solder) is rapidly moving, especially in the electronics industry.

[0004] To improve solder wettability and corrosion resistance, the external lead terminals of electronic components are mainly soldered (90% Sn-balance Pb) to respond to lead-free use. Is desired. Candidates for lead-free soldering are roughly classified into pure Sn, Sn-Ag (Cu), Sn-Zn, and Sn-Bi. Each has its own strengths and weaknesses. Has not been reached yet.

[0005] Pure Sn plating is the best lead-free plating in terms of cost and workability. It is considered influential. However, Sn plating has problems that whiskers are easily generated due to surface oxidation and internal stress, and that the solder wettability is liable to deteriorate with time, and there is a strong demand for improvement.

[0006] The Sn-Zn-based alloy is advantageous in that it does not need to change the current equipment process because the melting point is close to that of a conventional Sn-Pb-based alloy. Also, the mechanical strength of the plating film is excellent and the cost is also excellent. However, since Zn is an active metal species and is easily oxidized, the Sn-Zn alloy has very poor solder wettability, so it is considered that the possibility of practical application is the lowest at this time.

[0007] Solder paste is used for surface mounting electronic components on a substrate, and its use has been increasing in recent years. The solder paste is generally a solder alloy powder as a main component, and is obtained by adding a flux containing an adhesive, an activator, a thixotropic agent ij, a surfactant, a solvent, and the like. As lead-free solder pastes, Sn_Ag (Cu) -based alloys, Sn_Zn-based alloys, and Sn-Bi-based alloys are being studied. Eutectic temperature is considered a promising alternative. However, as described above, due to the susceptibility of Zn to oxidation, solder paste using Sn-Zn-based alloy as the solder powder undergoes an oxidation reaction with the activator contained in the flux, resulting in remarkable solder wettability and storage stability. There is a disadvantage that an inert gas atmosphere is required during reflow.

[0008] In order to address these problems, the present inventors have disclosed in Patent Document 1 (Japanese Patent Application No. 2002-304554) one or two acidic phosphate esters having a saturated or unsaturated alkyl group and an acidic phosphate ester thereof. A surface treatment agent characterized by containing salt was proposed.

[0009] Patent Document 2 (Japanese Patent Application Laid-Open No. 7-188942) particularly proposes an antioxidant characterized by comprising diphenyl phosphate and / or diphenyl phosphite. ing.

[0010] However, the phosphoric acid ester or the phosphite in the above-mentioned technology cannot obtain a sufficient antioxidant effect because the ester bond is decomposed by heat treatment at a relatively high temperature (200 ° C. or higher). For this reason, it is difficult with the above-mentioned technology to prevent oxidation of Sn and Sn alloy materials for lead-free solder, which generally raises the soldering temperature higher than before. Patent Document 1: Japanese Patent Application No. 2002-304554

Patent Document 2: Japanese Patent Application Laid-Open No. 7-188942

Disclosure of the invention

An object of the present invention is to provide a surface treatment agent that imparts oxidation resistance to metals, particularly Sn and Sn alloys, and improves solder wettability. Another object of the present invention is to provide a surface treatment agent that suppresses the generation of whiskers of Sn and Sn alloys.

The present inventors have conducted intensive studies on the suppression of oxidation of metals, particularly Sn and Sn alloy surfaces, and as a result, they have two or more phosphonic acid groups in one molecule and have an ester bond in the molecule. Surface treatment with a surface treatment agent containing a total of 0.1 Olg / L or more of one or more of compounds containing no and / or salts thereof imparts oxidation resistance and improves solder wettability. I found that I can do better. The solder paste containing the surface-treated Sn alloy solder powder showed a remarkable improvement in storage stability. Furthermore, it was found that the occurrence of whiskers was significantly suppressed in the surface-treated Sn and Sn alloy.

[0013] That is, the present invention is as follows.

(1) A compound containing two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, and / or a total of at least one or two or more of its salts. A metal surface treatment agent characterized by the following:

(2)-a compound having two or more phosphonic acid groups in the molecule and containing no ester bond in the molecule, and / or a total of at least one or more of salts thereof at least 0.1 Olg / L; surface treatment agent of metal, characterized in that to adjust the _P H to the 5 following solutions.

(3) The metal surface treating agent according to the above (2), further comprising a surfactant of 0.1 OlgZL-10 g / L.

(4) The compound having two or more phosphonic acid groups in one molecule and having no ester bond in the molecule and / or a salt thereof is represented by the following formula (1), (II) or (III) And / or a salt thereof with an alkali metal salt, an ammonium salt, or an amine compound, wherein the metal surface according to any one of (1) to (3) above, Processing agent.

[Chemical 1] c XYII 丄

(In the formula (I), x ¹ —x ³ and γ ¹ —γ X ³ each represent a hydrogen atom which may be the same or different, or a lower alkyl group having 115 carbon atoms.)

[Formula 2]

R

R ¹ \ I

N- [CH ₂ -CH ₂ -N] _n -R ⁴ (Π)

R ² ^

(In the formula (Π),

R ² and R ⁴ each represent the following groups (A) which may be the same or different; R ³ represents the following groups (A) or lower alkyl groups having 15 carbon atoms; Represents an integer of 1 to 3.

[Formula 3]

In the group (A), X ¹ and Y ¹ are the same as defined in the general formula (I). )

[Formula 4]

O X o

II I II HO-P -C- P-OH

HO Y OH

(In the formula (m), x represents a hydrogen atom or a lower alkyl group having 115 carbon atoms, and γ represents a hydrogen atom. And represents a lower alkyl group having 1 to 5 carbon atoms, a hydroxyl group, or an amino group. )

(5) The metal surface treatment agent according to any one of (1) to (4), wherein the metal is Sn or a Sn alloy.

(6) The method for surface treatment of a metal with a surface treatment agent according to any one of (1) to (5) above.

(7) An electronic component characterized by being subjected to surface treatment by the surface treatment method according to (6) above, or after plating on the conductor surface of the connection terminal portion of the electronic component or the substrate. Or a substrate.

(8) A solder ball or solder powder using a Sn alloy surface-treated by the surface treatment method according to (6).

(9) A ball grid array using the solder ball according to (8) as an electrical connection member.

(10) A mounted product, wherein the solder ball according to (8) is disposed on an electronic component and connected to a circuit board.

(11) A solder paste using the solder powder according to (8).

(12) A mounted product characterized by using the solder paste according to (11).

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the surface treatment agent of the present invention will be described in detail.

Examples of the metal to be treated with the surface treatment agent of the present invention include Fe, Ni, Co, Cr, Cu, Zn, Sn, Al, Mg, Ti, Ag, and Au, and these may be alloys. Les ,. In particular, Sn and Sn alloys are preferred. As a Sn alloy, a lead-free Sn alloy is more preferred because of problems such as environmental pollution. Examples of the Sn alloy that does not include a mouth include a solder alloy that includes one or more of Zn, Bi, Cu, In, Ag, and Sb in Sn.

[0019] A surface treating agent containing a total of at least 0.1 Olg / L of a compound having two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, and / or a salt thereof. By performing the surface treatment, oxidation resistance can be imparted to the surface of the material to be treated, and solder wettability can be improved.

It has two or more phosphonic acid groups in one molecule and does not contain ester bonds in the molecule If the amount of the compound and / or its salt is less than 0.01 g / L, the effect is small. Conversely, there is no upper limit on the amount of addition because there is no deterioration in the properties even if the amount of added koji is too large. More preferably, it is 0.1-10 Og / L.

Further, since the surface treatment agent of the present invention uses a compound containing no ester bond in the molecule, a sufficient antioxidant effect can be obtained even at a relatively high temperature where the ester bond is not decomposed by the heat treatment. . Therefore, lead-free soldering temperature is relatively higher than before

X

Sufficient oxidation resistance can be imparted to Sn and Sn alloy materials compatible with solder

[0021] The detailed mechanism of a compound having two or more phosphonic acid groups in one molecule is not clear as compared with a compound having two or more phosphonic acid groups in one molecule. Was found to be excellent. The number of phosphonic acid groups in one molecule is preferably 26 from the viewpoint of cost.

As a compound having two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, and / or a salt thereof, for example, the following general formulas (1), ()), and (III) And / or an alkali metal salt, an ammonium salt, and a salt thereof with an amine compound.

[0022] [Formula 5]

(In the formula (I), x ¹ —x ³ and Y ¹ —Y ³ each represent a hydrogen atom which may be the same or different, or a lower alkyl group having 115 carbon atoms.) [0023] [Formula 6]

(In the formula (Π),

[Formula 7]

[0024] [Formula 8]

O X o

II I II H O-P-C-P-O H

H O Y OH

(In the formula (ΠΙ), X represents a hydrogen atom or a lower alkyl group having 115 carbon atoms, and Y represents a hydrogen atom, a lower alkyl group having 115 carbon atoms, a hydroxyl group, or an amino group.)

As the compound represented by the above general formula (I), ditrilotrismethylenephosphonic acid and the like are particularly preferable because they are commercially available.

Similarly, as the compound represented by the general formula (II), ethylenediaminetetrakismethylenephosphonic acid, diethylenetriaminepentakismethylenephosphonic acid and the like are particularly preferred. As the compound represented by the general formula (ΠΙ), , 1-hydroxyethane-1,1,1-diphosphonic acid and the like are particularly preferred.

The alkali metal salt of the above compound is preferably a sodium salt, a potassium salt or the like. As a salt with a compound, triethylamine salt / triethanolamine salt and the like are preferable.

[0027] The surface treatment agent of the present invention can be used by dissolving a compound having two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, and / or a salt thereof in a solvent. it can. The solvent used is not particularly limited as long as it is soluble. For example, water is preferred in consideration of the power S, solubility, cost, and the like, which include polar solvents such as water and alcohols and glycols.

[0028] Further, in the case of an aqueous surface treating agent, it has been found that by adjusting the pH to 5 or less, the oxidation resistance of the surface to be treated is further improved. The pH of the surface treatment agent is more preferably pH 15 in consideration of the influence on the material and the like. As the pH adjuster, generally available acids and alkalis can be used.

[0029] Furthermore, by adding a surfactant to the aqueous surface treating agent at 0.01 to 10 g / L and adjusting the pH to 5 or less, the oxidation resistance of the surface to be treated is further improved. . Even if the amount of the surfactant added is less than 0.1 Olg / L or exceeds 10 g / L, the effect of oxidation resistance cannot be obtained. The amount of surfactant added to the surfactant is preferably 0.1 to 10 g / L.

As the surfactant, one or more kinds of commercially available anionic, cationic, nonionic and amphoteric surfactants can be appropriately selected and used.

Examples of anionic surfactants include sulfate ester type, sulfonate type, ester phosphate salt type, and sulfosuccinate type, and cationic surfactants include quaternary ammonium salt type and amine salt. Nonionic surfactants such as higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, polyoxyethylene polyoxypropylene block polymers, polyoxyethylene polyoxypropylene block polymers of ethylenediamine, and higher aliphatic surfactants Preferred are ethylene oxide adducts of amines and ethylene oxide adducts of aliphatic amides, and the amphoteric surfactants are preferably amino acid type, betaine type and the like.

When the pH is used in the range of 5 or less, it is preferable to appropriately select and use one or more of anionic and nonionic. Among them, among the nonionic surfactants, the polyethylene glycol type is particularly preferred, and higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, and polyoxyethylene polyoxypropylene are particularly preferred. Block polymers and the like can be particularly preferably used, and among the anionic surfactants, sulfate ester type and phosphate ester type are particularly preferable.

[0030] Further, the surface treatment agent of the present invention may contain an additive in an amount that does not impair the original properties for the purpose of imparting desired performance. Examples of the additive include a preservative, a pH buffer, and the like, and those conventionally known can be used.

[0031] The surface treatment of the metal using the surface treatment agent of the present invention may be any method that forms a film on the surface of the metal. For example, a method in which the metal is simply immersed in the surface treatment agent, a surface treatment Examples of the method include applying the agent using a shower or an apparatus such as an air coater, a blade coater, a rod coater, a knife coater, a gravure coater, a reverse coater, or a cast coater.

[0032] The shape of the metal to be surface-treated with the surface treatment agent of the present invention may be any shape such as a line, a plate 'band' foil, a particle, and a powder. It can process electronic components, substrates, solder balls, solder powder, etc.

By using the surface treatment agent of the present invention, the surface of the conductor of the connection terminal portion of the electronic component or the substrate is surface-treated, or the surface of the conductor is plated, and then the surface is treated, so that the oxidation resistance is excellent and the solder wets. An electronic component or a substrate having improved performance can be obtained.

Solder balls using the Sn alloy treated with the surface treatment agent of the present invention have excellent oxidation resistance, are arranged as ball grid arrays as electrical connection members, and are arranged on electronic components and connected to circuit boards. It can be used favorably as a mounted product.

[0033] Further, the Sn alloy powder is treated with the surface treatment agent of the present invention, and a flux containing an adhesive, an activator, a thixotropic agent, a surfactant, a solvent, and the like is added thereto to form a solder paste. You can also use it. This solder paste has a remarkable effect of improving the storage stability. Conventionally known adhesives, activators, thixotropic agents, surfactants, and solvents can be used.

Example

Hereinafter, the present invention will be described in detail with reference to Examples.

Examples 1 to 14 and Comparative Examples 1 to 5 Fifteen types of aqueous solutions containing two or more phosphonic acid groups in one molecule and containing no compound having an ester bond in the molecule or a salt thereof as an active ingredient were prepared (Examples 1 to 14 and Comparative Example 1). . Table 1 shows the breakdown.

On the other hand, the following pretreatment was performed on a copper material (C1020P, 10 mm × 25 mm × O. 2 tmm).

Alkali electrolytic degreasing (room temperature, 15AZdm ^2, about 30 seconds to process) → water washing → acid dip (10% sulfuric acid, room temperature, 5 seconds) → water washing → chemical polishing (CPB - 40, room temperature, 1 minute immersion) → water washing → Acid immersion (1

(0% sulfuric acid, normal temperature, 5 seconds) → water washing

This substrate was Sn plated with a thickness of about 5 xm (plating bath: Tincoat K (manufactured by Nikko Metal Plating Co., Ltd.), plating conditions: cathode current density 2A / dm ² , temperature 20 ° C , Liquid flow and force sword rocking).

[0036] The Sn-plated substrate (hereinafter referred to as Sn substrate) contains a compound having two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, or a salt thereof. After being immersed in the solution at a bath temperature of 60 ° C. for 10 seconds, it was washed with water and dried to obtain a test substrate.

The following evaluations were performed on these test substrates. Table 1 shows the test results.

Thermal oxidation resistance

After heat-treating these test substrates in an electric furnace maintained at 220 ° C for 1 hour in the air atmosphere, the solderability (zero cross time) with lead-free solder was measured by the meniscograph method under the following measurement conditions. .

Equipment: Solder checker SAT-2000 (less power)

Solder bath; Tin: silver: copper = 96 · 5: 3: 0.5 (bath temperature 245 ° C)

Flux: NA-200 (Tamura Kaken)

Immersion depth: 2mm

Immersion speed: 4mm / se

Immersion time: 5sec.

[0038] Moisture and oxidation resistance

After subjecting these test substrates to PCT treatment (leaving them in a closed oven at a temperature of 105 ° C and a humidity of 100% for 16 hours), the solderability (zero cross time) with lead-free solder was measured using a meniscus. It was measured by the cograph method in the same manner as in the term of thermal oxidation resistance.

Further, as a comparative example, a substrate treated with an isopropanol solution containing lg / L of dodecylphosphonic acid on the above Sn substrate (however, without water washing after the surface treatment, Comparative Example 2), Japanese Unexamined Patent Publication No. 7-188942 discloses a base material treated with an aqueous solution containing lgZL phosphonate lgZL (Comparative Example 3), the untreated Sn base material (Comparative Example 4), and the Sn base material. A substrate (Comparative Example 5) treated with the surface treatment agent (aqueous solution containing 0.1 g / L of diphenyl phosphate) was also evaluated. Table 1 also shows the test results.

[0040] [Table 1]

Table 1 Surface ¾¾W§J * and «S fruit (S n ****)

@ = Zero cross time 1 ¾ * ¾ 0 = zero cross time 1 second J¾ ± 3 «J * full, △ = zero cross time 3 seconds ¾ ± 5« * full, x = zero cross time 5 seconds JiLh

A copper material (C1020P, 1 Omm X 25 mm X 0.2 mm) subjected to the same pretreatment as in Example 114 and Comparative Example 115 was subjected to Sn- Snη plating with a film thickness of about 5 μm. (Plating bath: manufactured by Nikko Metal Plating Co., Ltd., plating conditions: cathodic current density 3 A / dm ² , temperature 35 ° C., pH 4.0, liquid flow and force swinging).

The Sn—Zn-plated substrate (hereinafter referred to as Sn—Zn substrate) was added to the solutions prepared in Examples 1-11, Comparative Examples 1-3, and Comparative Example 5 at a bath temperature of 60 ° C. After immersion for 10 seconds, the substrate washed with water, dried, and untreated were used as test substrates.

After aging was performed on these test substrates in the same manner as in Example 114 and Comparative Example 115, the solderability was measured. Table 2 shows the test results.

Further, as a comparative example, a surface treatment agent (lwt% isopropanol of monodioctadecynyl phosphate) described in Japanese Patent Application No. 2002-304554 was used for the untreated Sn—Zn substrate. And the treated substrate (Comparative Example 11) was also evaluated. Table 2 shows the test results.

[Table 2]

The Sn-plated substrate treated in the same manner as in Example 7 and the substrate not subjected to the surface treatment were allowed to stand in a constant temperature and humidity atmosphere of 85 ° C. and 85% humidity for 24 hours. After that, the substrate was sufficiently dried, and the surface was observed with a scanning electron microscope (SEM). In the case where the surface was not treated, many whiskers were observed (Comparative Example 12). No whiskers were observed in the treated products (Example 29).

Industrial applicability

[0045] A compound having two or more phosphonic acid groups in one molecule and having no ester bond in the molecule, and / or one or two or more of salts thereof in total of 0.1 Olg / L or more By treating the surface of the metal with a surface treatment agent containing it, it can impart oxidation resistance and improve solder wettability. By adjusting the pH of this surface treatment agent to 5 or less, and further adding a surfactant of 0.01 to 10 g / L, the oxidation resistance is improved.

[0046] The storage stability of the solder paste containing the Sn alloy solder powder subjected to the surface treatment using the surface treatment agent of the present invention is remarkably improved. Further, by treating Sn and the Sn alloy with the surface treatment agent of the present invention, the generation of whiskers can be significantly suppressed.

Claims

Claims [1] A compound having two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, and one or more of H and / or a salt thereof in a total of 0 A metal surface treatment agent containing at least 01 g / L. [2] A compound having two or more phosphonic acid groups in one molecule and containing no ester bond in the molecule, and / or one or more salts thereof in a total of 0.01 g / L or more A metal surface treatment agent, wherein the pH of the solution is adjusted to 5 or less. ¾ [3] The metal surface treating agent according to claim 2, further comprising a surfactant in an amount of 0.01 g / L to 10 g / L. [4] The compound having two or more phosphonic acid groups in one molecule and having no ester bond in the molecule, and / or a salt thereof is represented by the following formula (1), (Π) or (III). 14. The metal surface treatment agent according to claim 13, wherein the metal surface treatment agent is a compound to be used and / or a salt thereof with an alkali metal salt, an ammonium salt, or an amine compound.

[Chemical 1]

(In the formula (I), X ¹ X ³ and Y ¹ —Y ³ each represent a hydrogen atom which may be the same or different, or a lower alkyl group having 115 carbon atoms.)

[Formula 2]

R ³

R ¹ .I

N _ [CH ₂ _ CH ₂ _ N] _n — R ⁴ (Π)

R ² ^

(In the formula (Π),

R ² and R ⁴ each represent the following groups (A) which may be the same or different And R represent the following group (A) or a lower alkyl group having 115 carbon atoms, and n represents an integer of 113.

[Formula 3] c XYII 丄

[Formula 4] H

T O Y OH

[5] The metal surface treating agent according to any one of [14] to [14], wherein the metal is Sn or a Sn alloy.

[6] A method for treating a metal with a surface treating agent according to any one of claims 115.

[7] An electronic component or a component characterized in that a surface treatment is performed by the surface treatment method according to claim 6, after plating on the conductor surface of the connection terminal portion of the electronic component or the board, or after plating the surface. substrate.

[8] A solder ball or solder powder using a Sn alloy surface-treated by the surface treatment method according to claim 6.

[9] A ball grid array using the solder ball according to claim 8 as an electrical connection member.

[10] A mounted product, wherein the solder ball according to claim 8 is arranged on an electronic component and connected to a circuit board. A solder paste comprising the solder powder according to claim 8. A mounted product using the solder paste according to claim 11.