KR20120078181A - Electroless ni/pd/au plated structure - Google Patents

Abstract

The present invention relates to an electroless Ni / Pd / Au plated structure in which an electroless nickel (Ni) plated film, an electroless palladium (Pd) plated film, and an electroless gold (Au) plated film are formed on a connection terminal. In the plating structure according to the embodiment of the present invention, in the plating structure in which an electroless nickel (Ni) plating film, an electroless palladium (Pd) plating film, and an electroless gold (Au) plating film are formed on a connection terminal, The nickel, palladium, and gold plated films may each have a thickness of 0.01 μm or more and 0.1 μm or less, and the electroless nickel plated film and the palladium plated film may contain 5 wt% or less of phosphorus (P). .

Description

Electroless Ni / Pd / Au plated structure {Electroless Ni / Pd / Au plated structure}

The present invention relates to an electroless Ni / Pd / Au plated structure, and more particularly, to an electroless nickel (Ni) plated film, an electroless palladium (Pd) plated film, and an electroless gold (Au) plated on a connection terminal. It relates to an electroless Ni / Pd / Au plated structure in which a film is formed.

BACKGROUND With the increasing density of electronic components, technologies related to surface treatment of circuit boards have been diversified. In particular, the conventional electroless Ni / Au (hereinafter referred to as ENIG) and the electroless Ni / Pd / Au (hereinafter referred to as ENEPIG), which are recently attracting attention, have good solder connection reliability and wire bonding reliability. In addition, it is used in various fields. However, as the wiring becomes finer for higher density of the electronic components, problems of the conventional circuit board surface treatment technology have started to appear.

One of the problems is that it is difficult to secure space by fine patterning. Generally, the film thickness of ENIG is 3 ~ 7㎛. Among them, the thickest thickness is electroless Ni. This is because defect-free film performance is required because the role of electroless Ni is to suppress diffusion of underlying copper as a barrier layer. In addition, since ENEPIG exists in Pd as a barrier layer, it is possible to make the thickness of Ni thinner than that of ENIG. However, in some cases, a film thickness equivalent to ENIG is required in some cases. However, such a film thickness cannot cope with setting the inter-pattern space to 10 µm or less, which is the goal of the next generation technology.

In order to cope with such a fine pattern, the plating structure is changing from ENIG to ENEPIG. For example, in JP 3596335, the thickness of the electroless Ni film is 1 µm or more, the electroless Pd is 0.1 µm or more, and the substituted and self-catalyst gold is 0.04 µm or more. In addition, in JP A2008291348, the thickness of the electroless Ni is 0.1 µm or more, the electroless Pd is 0.3 µm or more, and the substituted and self-catalytic gold is 0.005 µm or more. On the other hand, although all are patent documents for ENEPIG, it is not prescribed about phosphorus contained in Ni film. Phosphorus concentration in the coating is important. Especially, in the case of solder bonding, if the phosphorus concentration is high, a layer containing a large amount of phosphorus (P rich layer) is formed on the solder and the underlying film interface, and the reliability after soldering is lowered. The same is true for Pd, and solder joint reliability in the coating will be lowered.

In addition, according to the prior art, solder and Ni junctions had problems in ENIG. This is because the corrosion resistance of the Ni film is poor, so-called black pads are generated in which the Ni film is corroded in emmersion gold or the like and the solder connection reliability is lowered. In general, solder connection reliability is good for direct bonding with copper. However, in the case where the Ni film thickness is 0.1 µm or more, there is a problem in that Ni remains on copper and becomes a nickel-solder connection.

In order to solve the above problems, the embodiments of the present invention are each formed with an electroless nickel, palladium, and gold plated film having a thickness of 0.01 μm or more and 0.1 μm or less, respectively, and 5 wt% or less in the electroless nickel plated film and the palladium plated film. An electroless Ni / Pd / Au plated structure containing phosphorus (P) is provided.

According to an aspect of the present invention, in the plating structure in which an electroless nickel (Ni) plating film, an electroless palladium (Pd) plating film, and an electroless gold (Au) plating film are formed on a connection terminal, the electroless nickel, The palladium and gold plating films each have a thickness of 0.01 μm or more and 0.1 μm or less, and the electroless nickel plated film and the palladium plated film each contain 5 wt% or less of phosphorus (P). / Au plated structures may be provided.

In addition, the electroless nickel plating film may contain 3 wt% or less of phosphorus (P).

In addition, the electroless palladium plating film may contain 1 wt% or less of phosphorus (P).

In addition, the electroless gold plating film may be formed of a substitution / reduction type.

According to another aspect of the invention, the electroless nickel (Ni) plating film, the electroless palladium (Pd) plating film, and an electroless gold (Au) plating film comprising the steps of sequentially forming on the connection terminal In the method of manufacturing a Ni / Pd / Au plated structure, the electroless nickel, palladium, and gold plated coatings each have a thickness of 0.01 μm or more and 0.1 μm or less, and each 5wt% in the electroless nickel plated film and the palladium plated film. A method for producing an electroless Ni / Pd / Au plated structure, which contains less than or equal to phosphorus (P) may be provided.

In addition, the electroless nickel plating film may contain 3 wt% or less of phosphorus (P).

In addition, the electroless palladium plating film may contain 1 wt% or less of phosphorus (P).

In addition, the electroless gold plating film may be formed of a substitution / reduction type.

Embodiments of the present invention, the thickness of the electroless nickel plated coating to 0.01㎛ more than 0.1㎛, electroless Ni / Pd improved solder connection reliability than conventional by controlling the content of phosphorus in the electroless nickel plated film and palladium plated film / Au plating structure can be provided.

1 is a cross-sectional photograph of a structure in which a lead-free solder ball is connected to a terminal for connecting a substrate solder ball manufactured in Example 1. FIG.
FIG. 2 is a cross-sectional photograph of a structure in which lead-free solder balls are connected to a terminal for connecting a substrate solder ball manufactured in Comparative Example 3. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The present invention relates to an electroless Ni / Pd / Au plated structure in which an electroless nickel (Ni) plated film, an electroless palladium (Pd) plated film, and an electroless gold (Au) plated film are formed on a connection terminal.

According to an aspect of the present invention, in the plating structure in which an electroless nickel (Ni) plating film, an electroless palladium (Pd) plating film, and an electroless gold (Au) plating film are formed on a connection terminal, the electroless nickel, The palladium and gold plating films each have a thickness of 0.01 μm or more and 0.1 μm or less, and the electroless nickel plated film and the palladium plated film each contain 5 wt% or less of phosphorus (P). / Au plated structures may be provided.

Phosphorus contained in the electroless nickel (Ni) plating film and palladium plating film according to an embodiment of the present invention may be 5wt% or less, and in the electroless nickel plating film, phosphorus (P) of 3wt% or less is It may be contained.

In general, the electroless Ni plating solution using hypophosphite contains phosphorus in the precipitation film. When the phosphorus concentration in the Ni film is increased, the diffusion rate into the solder is lower than in the crystalline state of Ni. For this reason, during soldering, nickel remains between copper and solder ,, and solder connection reliability is lowered due to black pad phenomenon. The electroless nickel (Ni) plating film of the present invention can be solved by including the phosphorus in the above range.

In addition, the thickness of the electroless nickel (Ni) plating film may be 0.01㎛ more than 0.1㎛. This is because when the film thickness is more than 0.1 µm, Ni is not completely diffused into the solder, and there is a problem that the Ni residue remains and the solder connection reliability is lowered. On the other hand, as the thickness of the film decreases, the diffusion of the underlying copper may be concerned, but the phosphorus content is low, so that the crystal is dense and sufficient barrier capability can be obtained even if the thickness is 0.1 m or less.

Phosphorus contained in the electroless nickel (Ni) plating film and the palladium (Pd) plating film according to an embodiment of the present invention may be 5wt% or less, and in the electroless palladium plating film, phosphorus (1wt% or less) P) may be contained.

Like the nickel, the electroless palladium plating film is preferably low in phosphorus content contained in the film, and the electroless palladium plating film may contain 1 wt% or less of phosphorus (P). This is because when phosphorus (P) of more than 1wt% is contained, the formation of P rich layer is suppressed by phosphorus remaining like nickel.

In addition, the thickness of the electroless palladium (Pd) plating film may be 0.01㎛ 0.1㎛. When the film thickness is more than 0.1 µm, since the Pd film inhibits the diffusion of Ni, the diffusion of Ni into the solder is not completely performed, and there is a problem that the Ni residue remains and the solder connection reliability is lowered.

In addition, according to an embodiment of the present invention, the electroless gold plating film may be formed in a substitution / reduction type. This is because, when the electroless gold plating film is formed in a general substitution type, corrosion holes are formed in the dense electroless Ni film and the electroless Pd film, thereby deteriorating copper diffusion preventing ability. That is, in the case of forming the substitution / reduction type, since the initial moment of the reaction is a substitution reaction and immediately proceeds to the substitution reaction, there is no attack on the Ni film and the Pd film, and as a result, a compact structure can be obtained.

In addition, the thickness of the electroless gold plating film may be 0.01㎛ more than 0.1㎛. It is because there exists a problem that excessive cost is consumed when a film thickness is more than 0.1 micrometer.

In addition, according to another aspect of the invention, comprising the steps of sequentially forming an electroless nickel (Ni) plating film, an electroless palladium (Pd) plating film, and an electroless gold (Au) plating film on the connection terminal In the method of manufacturing an electroless Ni / Pd / Au plated structure, the electroless nickel, palladium, and gold plated coatings each have a thickness of 0.01 μm or more and 0.1 μm or less, respectively, in the electroless nickel plated film and the palladium plated film. The method of manufacturing an electroless Ni / Pd / Au plated structure may be provided, wherein phosphorus (P) of 5 wt% or less is contained. Herein, the electroless nickel plated film may contain 3 wt% or less of phosphorus (P), and the electroless palladium plated film may contain 1 wt% or less of phosphorus (P), such as the electroless Ni / Pd / Au plated structure described above. P) may be contained, and the electroless gold plating film may be formed in a substitution / reduction type.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, these Examples are only for illustrating the present invention, and the scope of the present invention will not be construed as being limited by these Examples.

Test board fabrication

Hole pads are processed in the copper-clad laminate to form through-hole plating to form an etching resist, and a solder pad connecting terminal pad having a diameter of 600 µm is used in a plating resist which also serves as a solder resist so as to eliminate unnecessary copper by etching and depositing plating in unnecessary positions. To form a test substrate.

Pretreatment process

The pretreatment which forms a surface treatment by the following process was performed to the pad for solder ball connection terminals of the manufactured test board. The test substrate was immersed in degreasing solution ACL-007 (trade name, manufactured by UYEMURA Co., Ltd.) at 50 ° C. for 3 minutes, washed with water for 2 minutes, and then immersed in 100 g / L sodium perphosphate solution for 1 minute for etching. . Thereafter, the mixture was washed with water for 2 minutes, immersed in 10% sulfuric acid for 1 minute to carry out acid activity, and washed with water for 2 minutes. Next, it was immersed in 35 degreeC for 3 minutes in Accemarta MSR-28 (made by UYEMURA, brand name) which is a plating activation process liquid, and it washed with water for 2 minutes.

Example  1 to 3

Electroless Ni  Plated

The substrate subjected to the pretreatment was immersed in an electroless Ni plating solution (TOP NICORON LPH-LF: manufactured by OKUNO Co., Ltd.) having a phosphorous content of 3 wt% or less for 1 minute at 65 ° C. and then washed for 2 minutes.

Electroless Pd  Plated

The electroless Ni-plated substrate was prepared by XTP (P = 3wt%, manufactured by UYEMURA, trade name), PALLATOP LP (P <1wt%, manufactured by OKUNO, trade name), NEO PALLABRIGHT (P free, High Purity Chemicals Co., Ltd. product name) was formed under the conditions shown in Table 1 below and washed for 2 minutes.

Plating amount pH Temperature (℃) Processing time (min.) Film thickness (㎛) Example 1 XTP 7.2 50 10 0.1 Example 2 LP 7.3 60 10 0.1 Example 3 NEO 5.2 72 5 0.1

Electroless  gold plating

Each substrate plated with Pd according to Examples 1 to 3 was immersed in an electroless plating solution GoBright TSB-72 (manufactured by UYEMURA, Inc.) for 5 minutes at 80 ° C, washed for 2 minutes, and then blown at 150 ° C. Dried for 5 minutes.

Comparative example  1 to 3

Substrates subjected to the pretreatment process were each formed under the following conditions using an electroless Ni plating solution TOP NICORON GIB (trade name, manufactured by OKUNO Co., Ltd.) containing about 8wt% of phosphorus contained in the plating film.

pH Temperature (℃) Processing time (min.) Film thickness (㎛) Comparative Example 1 4.6 70 One 0.1 Comparative Example 2 4 0.4 Comparative Example 3 8 1.0

Subsequently, the substrates according to Comparative Examples 1, 2, and 3 were immersed in PALLATOP LP (P <1wt%, manufactured by OKUNO, trade name) for 10 minutes and washed for 2 minutes, followed by GoBright TSB-72 (manufactured by UYEMURA, Brand name) was immersed at 80 ℃ for 5 minutes, washed for 2 minutes, and then dried for 5 minutes with a 150 ℃ blow dryer.

Comparative example  4

The substrate subjected to the pretreatment was immersed in an electroless Ni plating solution (TOP NICORON LPH-LF: manufactured by OKUNO, trade name) having a phosphorous content of 3 wt% or less for 1 minute at 65 ° C., and then washed for 2 minutes.

Subsequently, the substrate was immersed for 10 minutes in MUDEN NORBLE PD (trade name, manufactured by OKUNO) having a phosphorus content of 6 wt%, washed for 2 minutes, and then immersed for 5 minutes at 80 ° C. in GoBright TSB-72 (trade name, manufactured by UYEMURA). After washing for 2 minutes, it was dried for 5 minutes with a blow dryer at 150 ℃.

Test Example

As described above, Pb-free solder balls (SAC305, φ760 μm: manufactured by Senju Metal Co., Ltd.) were connected to the terminals for board solder ball connection plated according to Examples 1 to 3 and Comparative Examples 1 to 4 in a reflow furnace. . After connection, the produced board | substrate was heat-processed at 150 degreeC for 100 hours, and the solder ball pull test was performed.

First, the semiconductor package substrate was fixed and the solder balls were pulled at a rate of 500 μm / sec vertically with a crump tool. Good mode was recorded if the solder balls were broken or peeled off the substrate for each ball pad, and if they were broken between the solder-base metals, the failure mode was recorded. In addition, the mode determination was visually observed by the 20 times optical microscope after performing a solder ball pull test. The test results are shown in Table 3 below.

　
　 nickel Palladium gold Solder pull test results Thickness P% Thickness P% Thickness Breakdown Mode (%) Connection strength (N) Example 1 0.1 μm 2.8 0.1 μm 2.9 0.1 μm 90 34.6 Example 2 0.1 μm 2.8 0.1 μm 0.8 0.1 μm 95 34.8 Example 3 0.1 μm 2.8 0.1 μm 0.0 0.1 μm 95 35.1 Comparative Example 1 0.1 μm 7.8 0.1 μm 0.8 0.1 μm 35 29.5 Comparative Example 2 0.4 μm 7.8 0.1 μm 0.8 0.1 μm 70 33.0 Comparative Example 3 1.0 μm 7.7 0.1 μm 0.8 0.1 μm 65 33.0 Comparative Example 4 0.1 μm 2.8 0.1 μm 6.1 0.1 μm 40 31.3

As a result of the solder pull test results of Examples 1 to 3, it was found that both the failure mode and the connection strength were superior to the comparative example. In addition, in Examples, the lower the phosphorus content of the palladium plated coating, the better the results were obtained.

As a result of the analysis, Comparative Examples 2 and 3 were obtained with the same results as ENEPIG currently used, and Comparative Examples 1 and 4 showed that the failure mode and the connection strength were lower than those of the Examples. This is thought to be the effect of phosphorus contained in the electroless Ni or electroless Pd film, and the fracture mode and the connection strength are deteriorated because phosphorus is concentrated at the interface between copper and solder.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional photograph of what connected the lead-free solder ball to the board | substrate for board | substrate solder ball connection manufactured in Example 1. FIG. FIG. 2 is a cross-sectional photograph of a lead-free solder ball connected to a board solder ball connection terminal manufactured in Comparative Example 3. FIG.

As indicated above, the present invention can provide an electroless Ni / Pd / Au plated structure with improved solder connection reliability.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (8)

In a plating structure in which an electroless nickel (Ni) plating film, an electroless palladium (Pd) plating film, and an electroless gold (Au) plating film are formed on a connection terminal,
The electroless nickel, palladium, and gold plating films each have a thickness of 0.01 μm or more and 0.1 μm or less, and the electroless nickel plating film and the palladium plating film each contain 5 wt% or less of phosphorus (P). Electroless Ni / Pd / Au Plating Structures. The electroless Ni / Pd / Au plated structure according to claim 1, wherein phosphorous (P) of 3 wt% or less is contained in the electroless nickel plating film. The electroless Ni / Pd / Au plated structure according to claim 1, wherein phosphorus (P) of 1 wt% or less is contained in the electroless palladium plating film. The electroless Ni / Pd / Au plating structure according to claim 1, wherein the electroless gold plating film is formed of a substitution / reduction type. An electroless Ni / Pd / Au plated structure comprising sequentially forming an electroless nickel (Ni) plated film, an electroless palladium (Pd) plated film, and an electroless gold (Au) plated film on the connection terminal. In the manufacturing method method,
The electroless nickel, palladium, and gold plating films each have a thickness of 0.01 μm or more and 0.1 μm or less, and the electroless nickel plating film and the palladium plating film each contain 5 wt% or less of phosphorus (P). Method for producing an electroless Ni / Pd / Au plated structure. The method for manufacturing an electroless Ni / Pd / Au plated structure according to claim 5, wherein phosphorous (P) of 3 wt% or less is contained in the electroless nickel plating film. The method for manufacturing an electroless Ni / Pd / Au plated structure according to claim 5, wherein phosphorus (P) of 1 wt% or less is contained in the electroless palladium plating film. The method of claim 5, wherein the electroless gold plating film is formed of a substitution / reduction type.

Images