JP2001060760A - Circuit electrode and method for forming the same - Google Patents

Abstract

(57) Abstract: The present invention relates to a circuit electrode provided in a package of an integrated circuit and the like, which imparts sufficient bonding strength to a solder bonding portion and reliably prevents surface oxidation of a Ni-P film. The purpose is to: A pattern formed on an organic substrate is provided.
And a circuit electrode which conducts with the circuit. An electroless high-concentration Ni-P plating film 30 containing phosphorus at a concentration of 7 to 12% by weight and covering a predetermined portion of the pattern 12 with a thickness of 3 to 10 μm is provided. Phosphorus is contained at a concentration of 3% by weight or less,
An electroless low-concentration Ni-P plating film 32 covering the electroless high-concentration Ni-P plating film 30 having a thickness of μm is provided. An electroless gold plating film 16 having a thickness of 0.05 to 0.5 μm is provided as an antioxidant film covering the surface of the electroless low-concentration Ni—P plating film 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit electrode and a method for forming the same, and more particularly, to a circuit electrode provided on a package of an integrated circuit or a printed circuit board, and a method for forming the same.

[0002]

2. Description of the Related Art Conventionally, for example, a BGA (Ball Grid Arra
y) Packages and CSP (Chip Scale Package) are known. In these packages, circuit electrodes in which a metal pattern such as copper (Cu) is covered by electroless plating are used.

FIG. 6 is a cross-sectional view of a conventional integrated circuit package having a circuit electrode having the above structure. A conventional integrated circuit package includes an organic substrate 10. Organic substrate 10
In the upper layer, a pattern 12 composed of a metal such as Cu
Are formed. The pattern 12 includes an electroless Ni-P plating film 14 (hereinafter, referred to as “Ni-P film 14”) and an electroless gold plating film 16 (hereinafter, referred to as “Au film 16”).
Covered by A passivation film 18 is formed on the surface of the organic substrate 10 in order to prevent the pattern 12 from being oxidized and the solder from flowing.

The Ni—P film 14 is mainly composed of Ni,
This is an electroless plating film containing P at a concentration of about 8% (% by weight, the same applies hereinafter), and is provided mainly for preventing diffusion of Cu forming the pattern 12. The Au film 16
Is an electroless plating film formed by a displacement plating method on the Ni-P film 14, and is formed mainly for preventing oxidation of the Ni-P film 14. According to the above configuration, the pattern 1
2, a circuit electrode is constituted by the Ni—P film 14 and the Au film 16. The above-mentioned circuit electrodes are formed via solder balls or solder bumps formed on the Au film
By performing wire bonding on the film 16,
It is joined to electrodes and the like of a printed circuit board.

[0005] The electroless plating film of Au is formed by a displacement plating method,
Alternatively, a film can be formed by a reduction plating method. However, when the Ni—P film 14 is a base, the growth of the Au film by the reduction plating method is hindered by the presence of Ni ions. Therefore, the Au film 16 needs to be formed by the displacement plating method before using the reduction plating method as described above.

[0006] The displacement plating method uses the Ni-P
Is replaced with Au to form an Au film. At this time, since Au is not replaced with P, during the plating process of the Au film 16, Au is preferentially deposited on a portion of the surface of the Ni—P film 14 where P does not exist. Therefore, in the process of plating the Au film 16, the substitution reaction between Ni and Au becomes faster as the concentration of P contained in the Ni—P film 14 is lower.

In other words, if the P concentration in the Ni—P film 14 is too high, the substitution reaction between Ni and Au is not sufficiently performed, and pinholes are easily formed in the Au film 16. Au film 1
If a pinhole occurs in 6, the oxidation of the Ni-P film 14 cannot be prevented, and it becomes difficult to perform soldering without using wire bonding or flux. Therefore, N
The P concentration in the i-P film cannot be set to an excessively large value.

In the conventional circuit electrode, the Ni-P film 14
Contains 6 to 8% of P. That is, Ni-P
P exists in about 6 to 8% of the surface area of the film 14. In the process of plating the Au film 16, P
Ni is replaced by Au in a portion where no Ni is present, whereby the erosion of Ni by Au proceeds in the vertical direction. At this time, if the reaction rate between Au and Ni is high, erosion by Au becomes remarkable, and a crack-like erosion portion is formed in the Ni—P film 14.

The reaction rate between Au and Ni is as follows.
The higher the concentration of P contained in No. 4, the higher the speed. For example, when the P content of the Ni—P film 14 is 3.5%, 0.5 μm of Au is obtained by plating for 10 minutes. When the content is 7.5%, the amount of deposited Au obtained by plating for 10 minutes is 0.3 μm. Further, when the content becomes 9.5%, the amount of Au deposition obtained by the plating treatment for 10 minutes becomes 0.05 μm or less. Therefore, the lower the P content of the Ni—P film 14, the greater the amount of Ni replaced by Au during the plating process, and the more easily crack-like eroded portions are formed in the Ni—P film 14.

The P concentration of the Ni-P film 14 where Ni is replaced by Au is relatively increased. On this occasion,
The P concentration increases significantly as the amount of Ni substituted with Au increases. Therefore, the P concentration near the interface between the Au film 16 and the Ni—P film 14 is relatively lower at the stage when the Au film 16 is formed as the P concentration initially contained in the Ni—P film 14 is lower. High concentration.

FIG. 7A shows a state after the solder balls 20 have been joined onto the circuit electrodes shown in FIG. FIG.
(B) shows a state in which the solder ball 20 has peeled off from the circuit electrode due to the execution of the shear test. FIG. 7
In FIG. 6, the same or corresponding portions as those shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

The solder balls 20 are made of lead (Pb) and tin (S
n). Solder ball 2
The Au film covering the Ni—P film 14 melts into the solder ball 20 in the process of bonding the “0” to the circuit electrode. As a result, a state where the solder ball 20 is in direct contact with the Ni-P film 14 is formed. After the solder balls 20 are in contact with the Ni-P film 14, Sn in the solder ball 20 is reacted with Ni in the Ni-P film 14 Ni / Sn compound 24 (Ni ₃ Sn ₄₎
Is generated.

In the process where the Ni / Sn compound 24 is generated, at the site where P exists on the surface of the Ni—P film 14, the diffusion speed of Ni is suppressed due to the presence of P. Therefore, if P is present at a high concentration on the surface of the Ni—P film 14, the Ni / Sn compound 24 tends to be columnar as shown in FIG. Further, since P is left in the Ni—P film 14 in the process of forming the Ni / Sn compound 24, P near the interface between the solder ball 20 and the Ni—P film 14 as compared with other portions. A P-rich layer 22 having a high concentration is generated.

The solder ball 20 and the Ni-P film 14 are
The i / Sn compound 24 is joined by acting as an adhesive. The P-rich layer 22 is made of a Ni / Sn compound 2
4 and the Ni-P film 14, so that Ni / S
It functions as a contaminant layer that weakens the adhesive action of n-compound 24. For this reason, by forming the P-rich layer 22, the bonding strength between the solder ball 22 and the Ni—P film 14 is reduced, and FIG.
As shown in (B), peeling easily occurs in the P-rich layer 22.

As described above, the P concentration on the surface of the Ni—P film 14 relatively increases as the erosion accompanying the formation of the Au film 16 becomes more remarkable. That is, the P on the surface of the Ni-P film 14
Is more concentrated as the erosion accompanying the formation of the Au film 16 becomes more remarkable. At the stage of joining the solder balls 20, Ni-P
The more P on the surface of the film 14 is concentrated, the more easily the P-rich layer 22 is formed. Therefore, as the Ni—P film 14 is significantly eroded with the formation of the Au film 16, the solder balls 2
0 and the Ni—P film 14 are apt to decrease in bonding strength.

In a crack-like eroded portion caused by significant erosion of the Ni—P film 14 by Au, N
The density of i is relatively largely reduced. Therefore, when the circuit electrode and the solder ball 20 are joined, the Ni / Sn compound 24 is less likely to be generated at the eroded portion. Also in this regard, when the erosion of the Ni-P14 film by Au is remarkable, the bonding strength between the solder ball 20 and the Ni-P film 14 is likely to decrease. Therefore, in order to secure the bonding strength of the solder ball 20, it is necessary to suppress the erosion of the Ni-P film 14 by Au.

As described above, the P concentration of the Ni—P film 14 is
The value cannot be excessively high from the viewpoint of preventing pinholes in the Au film 16. Further, the P concentration cannot be set to an excessively small value from the viewpoint of suppressing the erosion of the Ni—P film 14 by Au. The 6 to 8% conventionally used as the P concentration of the Ni-P film 14 is a value determined in consideration of both requirements.

[0018]

However, the conventional Ni-
Depending on the P film 14, it is not possible to sufficiently prevent the P-rich layer 22 from being eroded by Au and soldered. For example, when an Au film 16 of about 0.2 μm is laminated on a Ni—P film 14 containing 7.5% of P, Ni—P
In the range of about 1 μm from the surface of the film 14, the concentration of P is 1
0.2%. Furthermore, when the solder ball 20 is joined to the upper layer, the P concentration immediately below the Ni / Sn compound 24 becomes 17.5%.

For this reason, in the conventional circuit electrode using the Ni-P film 14 containing 6 to 8% of P, a solder defect may still occur between the solder ball 20 and the circuit electrode. For example, a Ni—P film 14 containing 6 to 8% of P and an Au film 1 having a thickness of 0.12 μm are formed on a Cu pattern 12.
In the case of a 0.6 mm-diameter circuit electrode on which No. 6 is laminated, the rate of occurrence of defective breakage by a shear test may exceed 40%.

Using a conventional circuit electrode, Ni by Au
As a method of suppressing the erosion of the P film 14 and avoiding the generation of the P-rich layer 22, for example, it is conceivable to reduce the thickness of the Au film 16. However, the Au film 16 has
Pinholes are more likely to occur as the film thickness is smaller. For this reason, if the Au film 16 is made thin, it is necessary to perform etching for removing the oxide film on the surface of the circuit electrode immediately before performing wire bonding or fluxless soldering. Therefore, if the Au film 16 is made thinner to avoid the generation of the P-rich layer 22, problems such as a decrease in circuit reliability and an increase in cost occur.

The present invention has been made to solve the above-mentioned problems, and can provide a solder joint with a sufficient bonding strength and reliably prevent the surface oxidation of the Ni-P film. It is an object of the present invention to provide a circuit electrode and a method for forming the same.

[0022]

According to the first aspect of the present invention,
A circuit electrode which is electrically connected to a pattern formed on an organic substrate and contains phosphorus at a concentration of 7 to 12% by weight,
an electroless high-concentration Ni-P plating film covering a predetermined portion of the pattern with a thickness of .mu.m, containing phosphorus at a concentration of 3% by weight or less,
-An electroless low-concentration Ni-P plating film covering the -P plating film;
An oxidation preventing film covering a surface of the electroless low-concentration Ni-P plating film.

According to a second aspect of the present invention, there is provided the circuit electrode according to the first aspect, wherein the antioxidant film has a thickness of 0.05 to 0.5 μm.
An electroless gold-plated film having a thickness of m.

According to a third aspect of the present invention, there is provided the circuit electrode according to the second aspect, wherein a gold wire is wire-bonded to a surface of the electroless gold plating film.

According to a fourth aspect of the present invention, there is provided the circuit electrode according to the first aspect, wherein the oxidation preventing film is an electroless solder plating film.

The invention according to claim 5 is the circuit electrode according to claim 4, wherein a solder ball or a solder bump is fixed to the surface of the electroless solder plating film, or a solder wire is wire-bonded. It is characterized by having.

According to a sixth aspect of the present invention, there is provided the circuit electrode according to any one of the first to fifth aspects, wherein the electroless high concentration Ni-P plating film and the electroless low concentration Ni-P plating are provided. A non-electric-field-concentration Ni-P plating film containing phosphorus at a concentration of 6 to 8% by weight or less is provided between the film and the film.

According to a seventh aspect of the present invention, there is provided the circuit electrode according to any one of the first to sixth aspects, wherein the circuit electrode comprises:
It is provided in a package of an integrated circuit.

The invention according to claim 8 is the circuit electrode according to any one of claims 1 to 6, wherein the circuit electrode is:
It is characterized by being provided on a printed circuit board.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a circuit electrode for forming a circuit electrode which is electrically connected to a pattern on an organic substrate, wherein a predetermined portion of the pattern is covered.
Containing phosphorus at a concentration of １２12% by weight, and
forming an electroless high-concentration Ni-P plating film having a film thickness of m, and containing phosphorus at a concentration of 3% by weight or less in an upper layer of the electroless high-concentration Ni-P plating film, and
Electroless low concentration Ni-P having a thickness of 0.5 to 10 μm
Forming a plating film;
Forming an antioxidant film on the upper layer of the P plating film.

According to a tenth aspect of the present invention, in the method for forming a circuit electrode according to the ninth aspect, the step of forming the antioxidant film includes a step of forming an antioxidant film on the upper layer of the electroless low-concentration Ni-P plating film by adding 0.1%. A step of forming an electroless gold plating film having a thickness of from 0.5 to 0.5 μm.

According to an eleventh aspect of the present invention, there is provided the method of forming a circuit electrode according to the tenth aspect, further comprising a step of wire bonding a gold wire to a surface of the electroless gold plating film. .

According to a twelfth aspect of the present invention, in the method for forming a circuit electrode according to the ninth aspect, the step of forming the oxidation-preventing film includes the step of forming an electric field-free layer on the Ni-P plating film without electric field. The method is characterized by including a step of forming a solder plating film.

According to a thirteenth aspect of the present invention, there is provided the method of forming a circuit electrode according to the twelfth aspect, wherein a solder ball or a solder bump is fixed on a surface of the electroless solder plating film, or a solder wire is wire-bonded. The method includes the step of:

According to the fourteenth aspect of the present invention, there is provided the ninth to the first aspects.
4. The method for forming a circuit electrode according to claim 3, wherein 6 to 8% by weight or less is provided between the electroless high-concentration Ni-P plating film and the electroless low-concentration Ni-P plating film. Forming a Ni-P plating film in an electric field-free concentration containing phosphorus at a concentration of.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals, and redundant description will be omitted.

Embodiment 1 FIG. 1 is a cross-sectional view of an integrated circuit package including a circuit electrode according to Embodiment 1 of the present invention. The integrated circuit package of the present embodiment is an organic substrate 10
It has. On the upper layer of the organic substrate 10, a pattern 12 made of a metal such as Cu is formed.

The upper layer of the pattern 12 has no electric field high concentration N
i-P plating film 30 (hereinafter, “high-concentration Ni-P film 30”)
) And an electroless low-concentration Ni-P plating film 32 (hereinafter, referred to as a “low-concentration Ni-P film 32”). The high-concentration Ni-P film 30 is a film containing Ni as a main component and containing P at a concentration of 11% (% by weight, the same applies hereinafter). In this embodiment, the high-concentration Ni-P film 30 is used.
Has a thickness of 5 μm. In addition, the above-mentioned 11
% Is a target value of the P concentration, and the actual concentration may be within the range of 7 to 12%. The above-mentioned 5 μm is a target value of the film thickness, and the actual film thickness may be in the range of 3 to 10 μm.

The low-concentration Ni—P film 32 is a film containing Ni as a main component and containing P at a concentration of about 2.5%. In the present embodiment, the low-concentration Ni-P film 32 has a thickness of 0.6 μm. Note that the above 2.5% is a target value of the P concentration, and the actual concentration may be 3% or less. The above-mentioned 0.6 μm is a target value of the film thickness, and the actual film thickness may be in the range of 0.5 to 1 μm.

The high-concentration Ni—P film 30 and the low-concentration Ni
The -P film 32 is formed by an electroless plating method. In the electroless plating method, the P concentration in the Ni-P film to be formed can be adjusted by adjusting the PH value of the plating solution, the plating temperature, and the like.

An Au film 1 is formed on the low concentration Ni—P film 32.
6 are formed. The Au film 16 is an electroless plating film formed by a displacement plating method. In this embodiment,
The Au film 16 has a thickness of 0.12 μm.
The above-mentioned 0.12 μm is a target value of the film thickness, and the actual film thickness may be 0.05 to 0.5 μm.

The above-described high-concentration Ni-P film 30 has a main purpose of preventing diffusion of a metal such as Cu constituting the pattern 12 and preventing erosion of the Ni-P film accompanying the formation of the Au film 16. It is provided as. The low-concentration Ni—P film 32 is provided for facilitating the formation of the Au film 16. Further, the Au film 16 has a low concentration of Ni-
It is formed mainly to prevent oxidation of the P film 32.

In the present embodiment, the above-described pattern 1
2. The high-concentration Ni-P film 30, the low-concentration Ni-P film 32, and the Au film 16 constitute circuit electrodes of an integrated circuit package. The circuit electrodes are connected to electrodes of a printed circuit board via solder balls or solder bumps formed on the Au film 16 or by wire bonding on the Au film 16.

On the surface of the organic substrate 10, in order to prevent the pattern 12 from being oxidized and to prevent the solder from flowing from the circuit electrodes,
A passivation film 18 is formed. In the process of forming the above-described circuit electrodes, the process of plating the Ni—P films 30 and 32 on the Cu pattern 12 can be performed at a temperature of about 90 ° C. or less. Further, according to the above-described structure of the circuit electrode, good adhesion between the Ni-P film (the high-melting-point Ni-P film 30) and the underlying metal (Cu) can be ensured without performing heat treatment. For this reason, the structure of the circuit electrode of the present embodiment can be sufficiently applied to the organic substrate 10 having a glass transition temperature of about 150 ° C.

Further, in the circuit electrode of the present embodiment, two plating layers are provided below the Au film 16, but since both are the same type of film (Ni-P film), two layers are formed. A sufficient bonding strength can be secured therebetween. Therefore, according to the circuit electrode of the present embodiment, compared to the case where a plurality of different types of plating layers are formed under the Au film 16,
Excellent reliability can be ensured.

In the present embodiment, the Au film 16 is formed by the displacement plating method as described above. The displacement plating method is a method of forming an Au film by replacing Ni in a base Ni—P film with Au. The generation of the Au film by the displacement plating method is easier as the P concentration in the underlying Ni—P film is lower. On the other hand, the underlying Ni-P film is made of P
As the Au concentration is lower, the erosion is more likely to occur in the vertical direction as the Au film 16 is formed.

In this embodiment, the low-concentration Ni—P film 32 and the high-concentration Ni—P film 30 are formed as a base of the Au film 16. Since the low concentration Ni-P film 32 has a low P concentration, the Au film 16 can be easily formed on the surface thereof. In addition, since the high-concentration Ni—P film 30 has a high P concentration, it is possible to effectively prevent the diffusion of Cu in the pattern 1 and to prevent the erosion of Au in the process of forming the Au film 16 from being effectively prevented.

That is, in this embodiment, since the Au film 16 is formed on the surface of the low-concentration Ni—P film 32, a high-quality Au film 16 without pinholes can be easily formed. In addition, a high concentration Ni-P
Since the P film 30 is formed, it is possible to effectively prevent the erosion by Au from proceeding deeper beyond the low-concentration Ni—P film 32. Therefore, according to the circuit electrode of the present embodiment, it is possible to form the high quality Au film 16 while appropriately suppressing the concentration of P on the surface of the Ni—P film.

As described above, in this embodiment, the P concentration of the high-concentration Ni—P film 30 is set to 7 to 12%. More specifically, the high-concentration Ni-P film 30 is formed with a target value of P concentration of 11% in consideration of manufacturing variations. If the P concentration is lower than 7%, it becomes difficult to obtain sufficient corrosion resistance. On the other hand, if the P concentration is higher than 12%, the film quality becomes brittle, and sufficient mechanical strength cannot be obtained.
According to the P concentration in the present embodiment, it is possible to avoid such inconveniences and provide the high-concentration Ni—P film 30 with sufficient corrosion resistance and sufficient mechanical strength.

As described above, in this embodiment, the thickness of the low-concentration Ni—P film 32 is adjusted to 0.5 to 1 μm. More specifically, the target value of the thickness of the low-concentration Ni—P film 32 is set to 0.6 μm in consideration of manufacturing variations.
The film is formed as When the thickness of the low-concentration Ni-P film 32 is 0.
If the thickness is less than 5 μm, it is difficult to form a high quality Au film 16. When the film thickness is larger than 1 μm, A
The amount of erosion in the vertical direction by u becomes large, and cracks easily occur in the film. According to the film thickness in the present embodiment, high quality can be given to the Au film 16 while avoiding such inconveniences and preventing occurrence of cracks.

In this embodiment, the low-concentration Ni-
The P concentration of the P film 32 is adjusted to 3% or less. In order to easily form a high-quality Au film 16, low-concentration Ni
The lower the P concentration of the -P film, the better. However, P
The lower the concentration, the more difficult it is to manufacture, and the more difficult it is to obtain stable quality. In the present embodiment, Ni-P
Considering that the variation of the P concentration in the film is about 1%, the low-concentration Ni-P film 32 is formed with 2.5% as the target value of the P concentration. In this case, it is possible to easily form the low-concentration Ni-P film 32 of stable quality while suppressing the maximum concentration of P to 3% or less.

FIG. 2 shows a state after the solder balls 20 are bonded on the circuit electrodes shown in FIG. In FIG. 2, the same or corresponding portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The solder balls 20 are made of eutectic solder containing Pb and Sn. During the process of joining the solder balls 20 to the circuit electrodes, the Au film 16 covering the low-concentration Ni—P film 32 melts into the solder balls 20. As a result, a state in which the solder ball 20 is in direct contact with the low-concentration Ni-P film 32 is formed. The surface of the low concentration Ni-P film 32 is
Since it was protected by the high-quality Au film 16, there is no oxide layer on its surface. Therefore, when the solder ball 20 is melted, the solder exhibits good wettability over the entire surface of the low-concentration Ni—P film 32.

When the solder ball 20 comes into contact with the low concentration Ni-P film 32, the Sn in the solder ball 20 becomes low concentration Ni-P.
By reacting with Ni in the film 32, the Ni / Sn compound 34 (Ni
₃ Sn ₄ ) is generated. The Ni / Sn compound 34 is Ni
-Not generated at sites where P is present on the surface of the P film. Therefore, when P is contained in the Ni-P film in contact with the solder at a high concentration, or the P concentration of the Ni-P film itself is low, but P is formed on the surface with the formation of the Au film 16. In the case of being concentrated, the generation of the Ni / Sn compound 34 is hindered.

In the present embodiment, the P concentration of the low-concentration Ni—P film 32 in contact with the solder ball 20 is suppressed to be low. The low-concentration Ni—P film 32 has a P
No erosion (crack-like erosion) condensing is formed. Therefore, the low concentration Ni-P film 32 and the solder ball 2
In the vicinity of the boundary with 0, as shown in FIG.
The n compound 34 is formed so as to spread over the entire surface of the low concentration Ni-P film 32. In this case, a larger bonding area between the solder and the circuit electrode can be ensured than when the compound is formed in a columnar shape (see FIG. 7).

In the process of forming the Ni / Sn compound 34, P in the low concentration Ni—P film 32 is left on the surface. Therefore, the low concentration Ni-P film 32 and the solder ball 2
Near the boundary with 0, a P-rich layer having a higher P concentration than other regions is generated. In this embodiment, the low concentration Ni-P
Since the P concentration of the film 32 is low, the P concentration of the P-rich layer can be suppressed to be low.

As described above, according to the structure of the circuit electrode of the present embodiment, a large joint area is secured between the solder ball 20 and the circuit electrode, and the P-rich layer generated near the boundary between them is formed. The P concentration can be suppressed low. Between the solder ball 20 and the circuit electrode, the larger the bonding area between them and the lower the P concentration of the P-rich layer, the higher the bonding strength. For this reason, according to the structure of the circuit electrode of the present embodiment, it is possible to secure a large bonding strength between the solder ball 20 and the circuit electrode. When a shear test was performed with the solder ball 20 having a diameter of 0.75 mm fixed to the circuit electrode of the present embodiment, the rate of occurrence of defective fracture was 0%.

FIG. 3 shows an Au wire 36 connected to the circuit electrode shown in FIG.
Shows the state after bonding. The bonding property of the Au wire 36 to the circuit electrode and the reliability of the Au wire 36 after wire bonding are greatly affected by the quality of the Au film 16. In the circuit electrode of the present embodiment, the pinhole of the Au film 16 can be prevented as described above, and the Au film 16 can be given high quality. For this reason, according to the circuit electrode of the present embodiment, excellent productivity and excellent reliability can be ensured even when connection with other electrodes and the like is ensured by wire bonding.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of an integrated circuit package having circuit electrodes according to the present embodiment. In FIG. 4, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

The circuit electrode of this embodiment is made of low-concentration Ni-P
A solder plating layer 38 is provided on the film 32 in place of the Au film 16 in the first embodiment. Solder plating layer 38
Is an electroless plating film having a thickness of about 2 μm.
The circuit electrodes of the present embodiment are connected to electrodes of a printed circuit board and the like via solder balls and solder bumps formed on the solder plating layer 38.

In this embodiment, the low concentration Ni—P film 3
2 functions in the same manner as in the first embodiment. as a result,
Layered Ni between the solder ball or solder bump and the circuit electrode
/ Sn compound is generated, and a P-rich layer having a low concentration is formed below the Ni / Sn compound. Therefore, also with the circuit electrode of the present embodiment, high bonding strength with solder can be obtained as in the case of the first embodiment.

Embodiment 3 Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of an integrated circuit package having circuit electrodes according to the present embodiment. In FIG. 5, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

The circuit electrode of this embodiment is made of high-concentration Ni-P
Between the film 30 and the low-concentration Ni—P film 32,
i-P plating film 40 (hereinafter referred to as "medium concentration Ni-P film 40")
). The medium-concentration Ni-P film 40 has a thickness of 0.1 mm.
An electroless plating film having a thickness of about 1 μm,
Contains P at a concentration of 8%. According to the circuit electrode of the present embodiment, the change in the P concentration in the Ni—P film interposed between the pattern 12 and the Au film 16 can be made gentler than in the case of the first embodiment. . For this reason, according to the circuit electrode of the present embodiment, a higher bonding strength can be provided to the Ni—P film than in the case of the first embodiment.

In the first to third embodiments, the circuit electrodes are limited to the electrodes of the integrated circuit package. However, the present invention is not limited to this. That is, the structure of the circuit electrode of the present invention can be widely applied to an electrode provided on an organic substrate, such as an electrode provided on a printed circuit board.

[0065]

Since the present invention is configured as described above, it has the following effects. Claim 1
According to the invention described in Item 9 or 9, an electroless high-concentration Ni-P plating film containing P at a predetermined high concentration under the oxidation preventing film;
An electroless low-concentration Ni-P plating film containing P at a predetermined low concentration is formed. Therefore, when soldering is performed on the upper layer, the Ni / Sn compound is generated in a layered manner, and the P concentration of the P-rich layer generated below the Ni / Sn compound is sufficiently suppressed. Therefore, according to the present invention, it is possible to realize a circuit electrode capable of securing a sufficiently large bonding strength with solder.

According to the second or tenth aspect of the present invention,
An antioxidant film can be formed by an electroless gold plating film. An electroless low concentration Ni-
A P plating film and an electroless high concentration Ni-P plating film are formed. Therefore, according to the present invention, it is possible to realize a high-quality electroless gold plating film without pinholes while suppressing erosion by gold.

According to the third or eleventh aspect of the present invention,
By bonding gold wires to the surface of the electroless gold plating film, circuit electrodes can be conducted to other electrodes and the like.

According to the fourth or twelfth aspect of the present invention,
An antioxidant film can be formed by an electroless solder plating film. According to the present invention, a circuit electrode can be realized at a lower cost than when the oxidation prevention film is formed by an electroless gold plating film.

According to the invention of claim 5 or 13,
Circuit electrodes can be conducted to other electrodes or the like via solder balls, solder bumps, or solder wires formed on the electroless solder plating film.

According to the invention of claim 6 or 14,
Electroless high concentration Ni-P plating film and electroless low concentration Ni-
By interposing the Ni-P plated film in the non-electric field between the P-plated film and the P-plated film, the change in the P concentration in the Ni-P film can be moderated. Therefore, according to the present invention,
High bonding strength can be imparted to the Ni-P film between the pattern and the antioxidant film.

According to the seventh aspect of the present invention, an integrated circuit package including the circuit electrode according to any one of the first to sixth aspects can be realized.

According to the eighth aspect of the present invention, a printed circuit board including the circuit electrode according to any one of the first to sixth aspects can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an integrated circuit package including a circuit electrode according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a state in which a solder ball is fixed on the circuit electrode illustrated in FIG.

FIG. 3 is a cross-sectional view showing a state where a gold wire is wire-bonded on the circuit electrode shown in FIG.

FIG. 4 is a cross-sectional view of an integrated circuit package including a circuit electrode according to a second embodiment of the present invention.

FIG. 5 is a sectional view of an integrated circuit package including a circuit electrode according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional integrated circuit package including circuit electrodes.

7 is a cross-sectional view showing a state after solder balls are fixed on the circuit electrodes shown in FIG. 7 and a state after the solder balls are peeled off by a shear test.

[Explanation of symbols]

Reference Signs List 10 organic substrate, 12 patterns, 16 electroless gold plating film (Au film), 18 passivation film, 30 electroless high concentration Ni-P plating film (high concentration Ni-P film), 32 electroless low concentration Ni-P plating film (Low concentration Ni-P film), 34P rich layer,
36 gold wire, 38 electroless solder plating film, 40
Non-electric field medium concentration Ni-P film (medium concentration Ni-P film).

Claims (14)

[Claims] 1. A circuit electrode, which is electrically connected to a pattern formed on an organic substrate, contains phosphorus at a concentration of 7 to 12% by weight, and has a thickness of 3 to 10 μm. High concentration Ni
-P plating film, containing phosphorus at a concentration of 3% by weight or less;
An electroless low-concentration Ni-P plating film that covers the electroless high-concentration Ni-P plating film with a thickness of: and an antioxidant film that covers the surface of the electroless low-concentration Ni-P plating film. Characteristic circuit electrodes. 2. The antioxidant film has a thickness of 0.05 to 0.5 μm.
2. The circuit electrode according to claim 1, wherein said circuit electrode is an electroless gold plating film having a thickness of: 3. A gold wire is wire-bonded to the surface of the electroless gold plating film.
The described circuit electrode. 4. The circuit electrode according to claim 1, wherein said oxidation preventing film is an electroless solder plating film. 5. The circuit electrode according to claim 4, wherein a solder ball or a solder bump is fixed on a surface of the electroless solder plating film, or a solder wire is wire-bonded. 6. The electroless high-concentration Ni—P plating film,
A non-electric field concentration Ni-P containing phosphorus at a concentration of 6 to 8% by weight or less between the non-electric field low concentration Ni-P plating film.
The circuit electrode according to any one of claims 1 to 5, further comprising a plating film. 7. The circuit electrode according to claim 1, wherein the circuit electrode is provided on a package of an integrated circuit. 8. The circuit electrode according to claim 1, wherein the circuit electrode is provided on a printed circuit board. 9. A method of manufacturing a circuit electrode for forming a circuit electrode that is electrically connected to a pattern on an organic substrate, comprising: a phosphorous concentration of 7 to 12% by weight so that a predetermined portion of the pattern is covered; And forming an electroless high-concentration Ni-P plating film having a thickness of 3 to 10 μm;
Forming an electroless low-concentration Ni-P plating film containing phosphorus at the following concentration and having a thickness of 0.5 to 10 μm; Forming a prevention film. The method for forming a circuit electrode, comprising: 10. The step of forming the antioxidant film includes forming an anti-oxidation film on the upper layer of the electroless low-concentration Ni—P plating film.
The method for forming a circuit electrode according to claim 9, further comprising forming an electroless gold plating film having a thickness of 5 to 0.5 μm. 11. The method according to claim 10, further comprising the step of wire bonding a gold wire to a surface of the electroless gold plating film. 12. The circuit according to claim 9, wherein the step of forming the oxidation preventing film includes the step of forming an electroless solder plating film on the electroless low-concentration Ni—P plating film. Method of forming electrodes. 13. The method for forming a circuit electrode according to claim 12, further comprising a step of fixing a solder ball or a solder bump on the surface of the electroless solder plating film or wire bonding a solder wire. 14. An electroless high-concentration Ni—P plating film and a non-electrolytic low-concentration Ni—P plating film,
Non-electric field concentration Ni containing phosphorus at a concentration of 8% by weight or less
The method for forming a circuit electrode according to any one of claims 9 to 13, further comprising a step of forming a -P plating film.