WO2006112215A1

WO2006112215A1 - Plated base material

Info

Publication number: WO2006112215A1
Application number: PCT/JP2006/304881
Authority: WO
Inventors: Akihiro Aiba; Kazumi Kawamura; Hirofumi Takahashi
Original assignee: Nippon Mining & Metals Co., Ltd.
Priority date: 2005-04-01
Filing date: 2006-03-13
Publication date: 2006-10-26
Also published as: CN101942652A; CN101151399B; JP4926053B2; HK1116838A1; KR20070114391A; CN101942652B; JPWO2006112215A1; TWI316095B; CN101151399A; TW200643215A

Abstract

Provide is a base material having an electroless plating film which is excellent in the corrosion resistance of a base metal and can improve the joinability by soldering, and further is advantageous over a conventional plating film from the view point of the production cost. A plated base material which has a base material and a multi-layer film formed thereon, characterized in that the multi-layer film comprises an electroless nickel plating film as an under layer, a substitution type of electroless palladium plating film having a thickness of not less than 0.2 nm and less than 10 nm or a weight of not less than 0.2432 μg/cm2 and less than 12.160 μg/cm2 as an intermediate film, and an electroless gold plating film as an upper layer.

Description

Specification

Plating substrate

Technical field

[0001] The present invention has an electroless nickel plating film on a substrate surface, a substitutional electroless palladium plating film as an intermediate layer, and an electroless gold plating film as an upper layer, and has corrosion resistance and solderability of a base metal. The present invention relates to a base material with excellent heat resistance.

Background art

[0002] Electroless gold plating is applied to terminals and circuit surfaces of electronic industrial parts such as printed wiring board circuits, IC packages, ITO substrates, and IC cards. More specifically, electroless gold plating is applied to improve the corrosion resistance, solder bondability, and bondability of copper foil or copper plated wiring on a substrate!

[0003] When sublimation-type electroless gold plating of a predetermined thickness is performed on the underlying electroless nickel plating film, the deposition of the electroless nickel film is accelerated immediately after the start of the plating reaction. The grain boundary part of the particle is selectively and strongly attacked, and the erosion of the precipitated particle proceeds deeply, and a defective part is formed under the gold plating film. In some cases, defective parts are continuous or concentrated, causing even the appearance of the gold-coated film to be poor (pitting corrosion occurs on the surface). In addition, even though the deposited gold film is thin, the depth of erosion is deep, the electroless nickel plating film is weakened by the substitution type gold plating solution and the adhesion with the gold plating film is insufficient. As a result, problems have been pointed out such as peeling during the durability test and insufficient soldering strength when soldering.

[0004] In order to solve this problem in electroless gold plating, improvement in the corrosion resistance of the base metal and improvement in the solderability have been desired. Under such circumstances, it has been proposed to improve solderability by inserting electroless palladium plating between electroless nickel plating and electroless gold plating (Patent Document 1).

Patent Document 1: Japanese Patent Publication No. 8-28561

Disclosure of the invention

Problems to be solved by the invention [0005] In the above proposal, the palladium plating layer of the intermediate layer is set to 0.01 to 0.2 / ζ πι (10 to 2 OOnm), and the palladium plating solution is a reduced type containing a reducing agent. (Self-catalytic type) is used. The problem with the reduced palladium plating solution is that bath management is very complicated due to low bath stability, and bath decomposition is likely to occur. In addition, since the film thickness is large as described above, a large amount of palladium, which is a noble metal, is used, which causes a problem in terms of cost.

[0006] The present invention provides a substrate having an electroless gold plating film that is excellent in the corrosion resistance of the base metal or can improve the solderability even when the palladium plating thickness of the intermediate layer is very thin. It is intended.

Means for solving the problem

[0007] As a result of intensive studies, the present inventors have found that when a substitutional electroless palladium plating layer is formed between an electroless nickel plating layer and an electroless gold plating layer provided on a substrate, The present inventors have found that even if the palladium plating layer is a thin film having a thickness of less than lOnm, it can be provided with sufficient base metal corrosion resistance and solderability, and the present invention has been achieved.

That is, the present invention provides:

[1] A plating substrate having a multilayer film on the substrate, the multilayer film being an electroless nickel plating film as a lower layer, and a film thickness of 0.2 nm or more and less than lOnm as an intermediate layer, or a weight of 0.243 ² gZcm ² 12. Substitutional electroless palladium plating film having a thickness of less than 160 gZcm ^{2 and} an electroless gold plating film as an upper layer,

[2] The plating base material according to [1], wherein the phosphorus content in the electroless nickel plating film is 15% by weight or less,

[3] The plating base material according to [1] or [2], wherein the electroless gold plating film is a sulfite-based non-cyan type,

About.

The invention's effect

[0009] According to the present invention, the coating amount of noradium which is a noble metal, which is expensive, can be greatly reduced. You can get results that are virtually indistinguishable from those used. The

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] The base material used in the present invention is a circuit of a printed wiring board, an IC package, an ITO substrate, a terminal of an electronic industrial component such as an IC card, or a circuit surface, but there is no particular limitation. It can be applied to substrates that require sticking.

[0011] The electroless nickel plating solution for forming the electroless nickel plating film used in the present invention is not particularly limited, and is usually used to form a base nickel plating film during electroless gold plating. What is used can be used. It is preferable to use a plating solution that forms a Ni-P plating film. In this case, the phosphorus content in the electroless nickel plating film is 15% by weight or less, preferably 5 to: LO weight%.

[0012] As the electroless gold plating solution for forming the electroless gold plating film, one that is used as a normal substitution type electroless gold plating solution is not particularly limited. However, a sulfite-based non-cyan type is preferred.

[0013] Further, it is important that the electroless palladium film inserted between the base electroless nickel plating film and the electroless gold plating film used in the present invention is a substitutional electroless palladium plating. It is. When a film is formed by reducing electroless palladium plating, the film thickness needs to be about 50 nm or more in order to control the film thickness and ensure sufficient solderability. If a type electroless plating is used, it can be made very thin. In the present invention, the thickness of the substitutional electroless palladium plating film is also important. In the present invention, the thickness of the electroless palladium plating film is formed in the range of 0.2 nm or more and less than lOnm. Or it is formed by 12. 160 gZcm ² below the range 0. 2432 / z gZcm ² or more by weight. Preferably, 0.2 nm or more and 9 nm or less, and by weight, ί or 0.22432 / zg / cm ² or more, 10.444 g / cm ² or less, more preferably ί or more 0.5 nm or more and 5 nm or less (0.608 gZcm ² or more 6. 080 gZcm ² or less). In or 0. 2432 gZcm than ² less than 0.2Ita m can not express the effect of the electroless palladium plating intermediate layer, also 10 nm, or 12. advantage in cost due to the increased use doses of the noble metal palladium reaches the 160 GZcm ² If ¾ is small, the strength of solder joints There is also a problem of causing a decrease.

For the substitutional electroless palladium plating solution itself for forming the intermediate plating film, a known plating solution can be used.

In the present invention, the thickness of the electroless nickel base coating is preferably 1 to 20 m, and the thickness of the electroless gold coating is preferably 10 to 500 nm.

Example

[0015] Examples of the present invention will be described below.

Examples 1-5, Comparative Examples 1-4

Plating process:

In Examples 1 to 5 and Comparative Examples 2 to 3, as shown below, the alkaline degreasing solution, the activator, and the electroless nickel plating solution were manufactured by Nikko Metal Plating, respectively. In addition, Nikko Materials products were used as substitutional electroless palladium plating solutions and electroless gold plating solutions.

The printed wiring boards for evaluation 1) and 2) shown below were alkaline degreased for 2 min at 45 ° C and pH 12.0 using an alkaline degreasing solution (Nikko Plating, P-1000). Next, soft etching (sulfuric acid + sodium persulfate system, 25 ° C, 2 min)

→ Sulfuric acid washing (3%, 25 ° C, 2min)

→ Pre-dip (hydrochloric acid, 25 ° C, lmin)

→ Acquisition of activator (Nikko Plating Co., Ltd., KG-522 (Salt and salt system, Pd concentration: 0.12gZL, 25.C, pH <l. 0, 30s))

→ Sulfuric acid cleaning (3%, 25 ° C, 10s)

→ Electroless nickel plating (Nikko Plating, KG-530 (88 ° C, pH 4.5, 25 min, P content 7%))

→ Substitutional type electroless palladium plating (manufactured by Nikko Materials Co., Ltd., CF-400 (Salt-based system, Pd: 0. lg / 25. C, pH2.0, lmin))

→ Each electroless gold plating (manufactured by Nikko Materials, CF-500SS (sulfurous acid system, Au concentration: 1. Og ZL, 80 ° C, pH 7.5, 20 min)) was performed in this order. In addition, lmin water washing process is included except for pre-dip → activator beta. Evaluation board:

1) Printed wiring board with 500 resist openings 0.448πιπιΦ

2) Resist opening 1 ~: Printed wiring board with LOmm pad

In addition, Comparative Example 1 was used without the substitution type electroless palladium plating, and reduced electroless palladium plating (Nippon Materials CA-400 (Pd: 0.8gZL) was used instead of the substitution type electroless palladium plating. 43 ° C, pH 7.5, 5 min)) was used as Comparative Example 4.

[0016] The following evaluation was performed on the printed wiring board on which the three-layered film was formed as described above.

Corrosion resistance:

After predetermined plating on the substrate of 1), the substrate was immersed in 20 vol% nitric acid aqueous solution for lOmin, washed with water and dried. Thereafter, the gold-plated appearance of all the pads was observed with an optical microscope at 50 times. The evaluation criteria were ◯ when the discoloration was less than 1% in 500 pads, △ when less than 1-10%, and X when more than 10%.

[0017] Solder wettability:

After the predetermined plating treatment was performed on the substrate of 2), the substrate was heat-treated at 160 ° C. for 24 hours. After that, flux was applied to 10 pads with 3mm openings, and 0.6πιπιΦ Sn— 4. OAg— 0.5Cu solder balls were placed on the center of the pad and reflowed at a peak temperature of 250 ° C in a reflow oven. Solder wetting spread is 1.5 for ≧ 1.5πιπιΦ, △ for less than 1.2 to 1.5mm, and X for less than 1.2mm.

[0018] Solder joint strength:

After the predetermined plating treatment was performed on the substrate of 1), the substrate was heat-treated at 160 ° CX for 24 hours, and then flux was applied to 20 pads of 0.48 mmΦ, and 0.6πιπιΦ of Sn— 4. OAg— 0 . 5 Cu solder balls were mounted and reflowed at a peak temperature of 250 ° C in a reflow oven.

Bond strength was measured by a heated pull method using a bond tester 4000 manufactured by Digi Corporation.

[0019] In addition, the palladium cost is a relative cost when the palladium metal price is set to 1 in the case where a reduced-type palladium plating solution is used and a 50 nm thick palladium plating film is formed (Comparative Example 4).

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Claims

The scope of the claims

[1] A plating substrate having a multilayer film on a substrate, the multilayer film being an electroless-Neckel plating film as a lower layer, and a film thickness of 0.2 nm or more and less than lOnm as an intermediate layer, or a weight of 0.2432 gZcm ² or more 12. Substitution type electroless palladium plating film having a thickness of less than 160 gZcm ² and an electroless gold plating film as an upper layer.

[2] The plating base material according to claim 1, wherein the phosphorus content in the electroless nickel plating film is 15% by weight or less.

[3] The plating base material according to claim 1 or 2, wherein the electroless gold plating film is of a sulfite type non-cyan type.