JP2001342599A - Plating apparatus, plating method and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming continuously plural combinations of plated films with a single transportation rail and forming the plated films with a high quality and uniform thickness on a lead frame and a surface of the lead. SOLUTION: A plating apparatus comprises several plating bath tanks under the transportation rail and plating a liquid storage tank beside the plating bath tank. The sort of plated film to be formed on an electro-conductive member 21 can be selected by means of moving the plating liquid back and forth between the plating bath tank and the plating liquid storage tank. Thus, several combinations of plated films can be formed continuously on an electro- conductive member with a single transportation rail.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a plating apparatus, a plating method, and a semiconductor device manufacturing method for forming at least two plating film layers on a lead and a lead frame mainly composed of a Ni alloy.

[0002]

2. Description of the Related Art A lead material in which the surface of a conductive member such as simple Cu, a Cu alloy or an Fe--Ni alloy is coated with a single Sn or Sn alloy plating layer is a simple Cu or Cu alloy.
It has the excellent conductivity and mechanical strength of the alloy.
In addition, the lead material is a high-performance conductor having both corrosion resistance and good solderability provided by Sn alone or Sn alloy. Therefore, they are frequently used in the field of electric and electronic devices such as various terminals, connectors, and leads, and in the field of power cables.

When a semiconductor chip is mounted on a circuit board, the outer lead portion of the semiconductor chip is subjected to hot-dip plating or electroplating using an Sn alloy to improve the solderability of the outer lead portion. Has been done. A typical example of such a Sn alloy is solder (Sn-
(Pb alloy) and has good solderability and corrosion resistance, so that it is widely used as industrial plating for electrical and electronic industrial components such as connectors and lead frames.

FIG. 7 is a cross-sectional view showing a basic structure of a lead material taken along the line AA in the semiconductor lead frame shown in FIG. For example, the conductive member 21 is made of Cu, a Cu-based alloy containing Cu as a main component, or Fe-Fe containing Ni as a main component.
-It is composed of a Ni-based alloy. The surfaces of the conductive members 21 are plated with two layers of different metal materials. For example, the first plating film 22 of Sn and S
The n-Bi second plating film 23 is formed in this order. Here, assuming that the thickness of the first plating film 22 is t ₁ and the thickness of the second plating film 3 is t ₂ , t ₁ is about 3 to 15 μm,
When t ₂ is set to about _{1 to 5} μm and t ₂ / t ₁ is set to about 0.1 to 0.5, in terms of cost, solderability and heat resistance, solder joint strength, aluminum wire, etc. It is known that it has good characteristics also in terms of the welding strength of the welded portion and that the performance as a lead material can be improved, which is preferable.

FIG. 8 shows the layout of the entire automatic plating apparatus. First, in the alkaline electrolytic cleaning bath 31, organic contaminants, such as oils and fats, which inhibit the adhesion and solderability of the solder plating film on the surface of the conductive member 21 are removed. Next, after being washed in the rinsing bath 32, a chemical etching process (basically, a process using an oxidation-reduction reaction) is performed in the chemical etching bath 33, and unevenness is caused by the presence of grain boundaries and inclusions. The surface of the conductive member 21 having a proper surface is made uniform.

Next, after being washed in the washing bath 34, the oxide film adhered in the washing bath 34 is removed in the acid activation bath 35. Next, after being washed in the rinsing bath 36, plating is performed in the solder plating device 37. Since the solder plating solution is strongly acidic, the surface after plating is acidic. On such a surface, the film discolors over time, and the solderability deteriorates. For this purpose, in the washing bath 38 and the neutralization bath 39, the acid remaining on the plating surface is neutralized, and the adsorbed organic substances are removed. Thereafter, the conductive member 21 which has been washed in the rinsing bath 40 and the hot tub 41 and dried in the drying device 42 is dried.

FIG. 9 is a sectional view of the chemical etching bath 33 in the BB direction in the entire plating apparatus shown in FIG.

The function of the chemical etching bath 33 is as described above. Here, the mechanism of the plating apparatus will be described. In this plating apparatus, both the lateral feed type pusher 331 and the transport rail 332 can move up and down. Then, the upper limit position and the lower limit position of the movable range are determined, and the moving range is repeated. Hanging hook 3
33 are transport rails 33 at appropriate intervals according to the work purpose.
Multiplied by two. It is usually the distance between the centers of adjacent bathtubs. Then, the auxiliary plating rack 334 hanging the conductive member 21 to be plated is hung on the hanging hook 333 and set in the plating apparatus. Next, the lateral feed type pusher 331 will be described.
The distance between the transverse feed type pushers 331 is basically equal to the distance between the centers of the adjacent bathtubs. The lateral feed type pusher 331 is mounted on one arm, and the hook 33 for hanging in the working direction.
When 3 is advanced by 1 span, it returns by that amount. And, this lateral feed type pusher 331 is 1 at the upper limit position.
Span feed and return at the lower limit position.
The transport rail 332 moves in the up-down direction but does not move in the traveling direction. By repeating this operation, the plating apparatus functions.

The above-described plating apparatus has one plating pretreatment line and one solder plating line. For example, when a Sn plating film is formed on the first plating film 22 on the conductive member 21 and a Sn—Bi plating film is formed on the second plating film 23, and when the first plating film 22 is formed on the conductive member 21 by Sn.
In some cases, an Sn—Ag plating film is formed on the second plating film 23 and the second plating film 23. In this case, the same Sn plating solution can be used for both the first plating film, but the plating solution used for the second plating film is different. Therefore, after the former plating film is formed on the conductive member 21, the plating apparatus is stopped once, the plating solution in the bath is replaced with a plating solution for the latter, and then the plating film is formed on the next conductive member 21. Had formed.

Further, in the above-described solder plating method and the plating apparatus used therefor, the plating bath in the plating line has a plating solution for forming a plating film on the conductive member 21 and electrodes for supplying current. Here, an anode installed in the plating bath mainly uses an anode in electroplating. Then, the conductive member 21 is immersed in the plating bath. At this time, the conductive member 21 forms a cathode to form a plating film. At this time, the conductive member 21 is replaced with a rectangular plating auxiliary rack 3 composed of two main pillars.
34 for plating. For example, conductive members 21 having different package sizes, conductive members 21 having different package designs, and conductive members 21 having different materials are used.
and so on. When forming a thick plating film on the conductive members 21, a plating operation is performed by applying a strong current density to the plating solution. Thus, plating films of various thicknesses have been formed mainly by giving strength to current density.

In the electroplating, it is known that the current density increases toward the end of the conductive member 21 and the plating film is formed thicker. The upper limit of the range of the current density suitable for the plating solution is called the maximum current density. By utilizing this maximum current density, high-speed plating and plating time can be reduced. However, if the maximum current density is exceeded, clouding will occur on the plated surface, and burnt or powdery deposits will be possible. It is also known that the plating film stops being formed when the current density reaches the limit current density.

[0012]

As a first problem, as described above, this solder plating apparatus has one plating pretreatment line and one solder plating line. Therefore, when a plurality of combinations of plating films are formed on the conductive member 21, when the combination of plating films is changed, there is a problem that the work cannot be performed continuously. In other words, in this plating apparatus, it was possible to successively immerse the conductive members 21 in the prepared plating solution to continuously form plating films of the same combination of plating films. However, a plurality of combinations of plating films could not be continuously formed on the conductive member 21 depending on the intended use of the conductive member 21 to be plated. In other words, there is a problem that extra time and labor are required for replacing the plating solution in the solder plating line.

In addition to the above, a great deal of labor has been spent on managing the solder plating line. For example, there is a case where, after using a plating solution as one plating bath, another plating solution having a different composition from the plating solution is used. At this time, the composition of the latter plating solution is changed unless the former plating solution is removed without fail. In addition, if the composition of the plating solution used is different, the anode used in the plating bath must be changed and replaced. In other words, there is a problem that a great deal of labor is spent on maintenance such as plating solution management or plating bathtub management.

As a second problem, as described above, in the solder plating method and the plating apparatus used therefor, the plating bath in the plating line is used to supply a plating solution for forming a plating film to the conductive member 21 and a current. It has electrodes. Then, a plating film was formed using this plating apparatus. However, there are various types of conductive members 21 depending on the size and design of the surface area. Therefore, although the current flows from the anode to the cathode, the conductive member 2 serving as the cathode
A uniform current does not always pass through any part of the surface of the device 1. In other words, each part of the conductive member 21 is not necessarily equidistant from the anode. In this plating apparatus, the conductive member 21 is placed on a rectangular plating auxiliary rack 334 having two main pillars to perform a plating operation. Therefore, since the conductive member 21 receives the current density from the anode as one surface, the current density is concentrated at the end of the conductive member 21 and the plating film is formed thicker, and the center of the conductive member 21 is compared with the end. A thin plating film was formed. When forming a plating film on the conductive member 21,
There has been a problem that plating is performed at a place where the current density is strong, and the plating film thickness and the plating film composition distribution are not optimized and uniform.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and a plating apparatus according to the present invention is a plating apparatus having a plating pretreatment line and a plating line. Has a plurality of plating baths, and a plating bath containing a plating solution is provided in a desired plating bath.

In the plating apparatus of the present invention, preferably, the plating line has a plurality of plating baths below the transport rail. Then, a plating solution storage bath is provided corresponding to the plating bath, and a function of moving the plating solution between the baths is provided. Alternatively, a plurality of plating baths and a plating solution storage bath are respectively provided below the transfer rail, and a function of moving the plating solution between the baths is provided. This makes it possible to form a plurality of combined single-layer or two- or more-layer plating films continuously on the conductive member with one transport rail.

Further, the present invention has been made in view of the above-mentioned conventional problems, and a plating method of the present invention comprises forming an electrode for supplying a current and a plating film in a plating bath containing a desired plating solution. In the plating method of forming a plating film by arranging a conductive member to be energized, a current density flowing from the electrode is set within an optimal current density range of the plating solution,
A plating film is formed on the conductive member after the conductive member is installed on a plating auxiliary rack.

In the plating method of the present invention, preferably, the conductive member and the auxiliary plating rack are integrally used as another electrode different from the electrode, and the auxiliary plating rack is connected to the electrode and the conductive member. In between, the plating film thickness and the plating film composition distribution can be adjusted.

Further, in view of the above-mentioned conventional problems, the plating apparatus of the present invention comprises an electrode for supplying a desired plating solution and a current in a plating bath, and a conductive member provided on a plating auxiliary rack. A plating apparatus for forming a plating film by forming the plating film by installing the conductive member in the plating auxiliary rack made of a member made of a conductive material.

In the plating apparatus of the present invention, preferably, the auxiliary plating rack is a rectangular parallelepiped having four main pillars, and the conductive member is provided in the auxiliary plating rack to form a plating film. Thereby, a more uniform current density can be applied to any part of the conductive member with respect to various conductive members having different surface areas, designs, and the like.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, as a first embodiment,
Referring to FIG. 1, FIG. 2 and FIG. 7, in a plating apparatus having a plating pretreatment line and a plating line, the plating line has a plating bath for forming a plating film layer of a plurality of patterns, A plating apparatus characterized in that a bath is provided with a bath for storing a plating solution is described.

FIG. 1 is a layout schematically showing the functions of a solder plating line for implementing the plating apparatus according to the present invention. In this solder plating line, a pre-dip bath 43, a first plating bath 44, a second plating bath 45,
The third plating bath 46 and the washing bath 47 are provided on the transfer rail 42.
It is installed under. Then, they are fed one pitch at a time by a lateral feed type pusher 41, and a plating film is formed on the conductive member 21 (see FIG. 4) by using these baths as in the conventional case.

In the present invention, as a first mode, a bath for storing a plating solution is provided as necessary corresponding to the plating bath. For example, as shown in FIG. 1, the first plating bath 44 is not provided with a plating solution storage bath, and the first plating bath 49 for the second plating bath 45 is replaced with the first plating bath 49 for the third plating bath 46. Two plating baths 50 are provided. In this case, in order to efficiently use the working space, and when storing the plating solution, a plating solution storage bath was installed under the plating bath so that the plating solution could be stored in a short time. Thus, in this solder plating line, a plurality of combinations of plating films can be continuously formed on the conductive member 21 with one transfer rail according to the intended use.

FIG. 2 is a layout simply showing the function of a solder plating line for implementing the plating apparatus of the present invention, similarly to FIG. 1 described above. In this solder plating line, a pre-dip bath 53, a first plating bath 54, a second plating bath 55, a third plating bath 56, a washing bath 5
7 is installed below the transport line 52. Then, they are fed one pitch at a time by a lateral feed type pusher 51, and a plating film is formed on the conductive member 21 using those baths.

As a second mode, a plating solution storage bath is provided for all the plating baths. For example, as shown in FIG.
The first plating solution storage bath 59 for the second plating bath 55
The second plating solution storage bath 60 for the third plating bath 56.
Third plating solution storage baths 61 are provided. Also in this case, a plating solution storage bath was provided below the plating bath as in the first embodiment. Thus, in this solder plating line, a plurality of combinations of plating films can be continuously formed on the conductive member 21 which can be plated by one transfer rail according to the intended use.

More specifically, in the first embodiment, the mechanism of transport of the solder plating line is the same as that shown in FIG. For example, in the solder plating line of FIG. 1, the first plating bath 44 is filled with a Sn plating solution,
The plating bath 45 contains a Sn-Bi plating solution.
The third plating bath 46 contains a Sn-Ag plating solution. In these plating baths, necessary plating baths are selected according to the intended use of the plated conductive member 21, and the plating solution in the plating bath that is not required moves to the plating solution storage bath. However, in this embodiment, the plating solution is always contained in the first plating bath 44 containing the plating solution of Sn, and the conductive member 21 is immersed in the plating solution of Sn. As a result, a single-layer Sn plating film is formed on the conductive member 21, or a Sn-Bi or Sn-Ag plating film is formed on the first layer of Sn and the second layer. The structure of the lead material is the same as that of FIG.

First, a case in which only the first plating film 22 of a single Sn layer is formed on the conductive member 21 will be described. Here, the first plating bath 44 containing the Sn plating solution is used.
Always contains the Sn plating solution, and the conductive member 21
Then, a Sn plating film is formed. First, the conductive member 21 treated in the above-mentioned plating pretreatment line is subjected to removal of the surface hydroxyl film in the pre-dip bath 43 and immersed in the Sn plating solution in the first plating bath 44. In the meantime, in the second plating bath 45 and the third plating bath 46,
Since no plating film is formed on the conductive member 21, the plating solution in the bath moves to the first plating solution storage bath 49 and the second plating solution storage bath 50. Sn in the first plating bath 44
The conductive member 21 having the plating film formed thereon is transported to the second plating bath 45 and the third plating bath 46, but the plating bath does not contain a plating solution, so that no plating film is formed. Next, the surface of the conductive member 21 on which the plating film has been formed is washed in the washing bath 47. As a result, a single-layer Sn plating film is formed on the conductive member 21.

Second, a case in which two layers of the first plating film 22 and the second plating film 23 are formed on the conductive member 21 will be described. The step of forming a plating film on the conductive member 21 is the same as the above-described content. First, since the first plating bath 44 always contains the Sn plating solution, the conductive member 2
1, a first plating film 22 of Sn is formed. And
Depending on the use of the conductive member 21, the second plating film 2
3. Select a plating bath to form 3. Here, first, S
When forming the n-Bi second plating film 23, the Sn-Ag plating solution in the third plating bath 46 is moved to the second plating solution storage bath 50. Then, when the second plating film of Sn—Ag is formed next, the S
The n-Bi plating solution is moved to the first plating solution storage bath 49, and the second plating solution storage bath 50 is transferred to the third plating bath 46.
From the plating solution of Sn-Ag. As a result, a two-layer plating film of Sn and Sn—Bi or Sn and Sn—Ag is formed on the conductive member 21.

Here, in the plating apparatus shown in FIG. 1, the metal material of the plating solution in the first plating bath 44 is Sn, the metal material of the plating solution in the second plating bath 45 is Sn-Bi, The metal material of the plating solution of the bathtub 46 is Sn-
Ag. And since the solution except those metals and the solvent for dissolving them has the same liquid composition, the conductive member 21
And a plating film can be formed continuously. But,
In some cases, a plating film is formed on the conductive member 21 with plating solutions having different liquid compositions. At this time, a plating bath containing pure water is prepared between plating baths having different plating liquid compositions, and the surfaces of the plated conductive members 21 are washed, so that plating solutions having different liquid compositions are mixed. To prevent. And when this pure water is not needed, it is put in a plating solution storage bath. Thus, a plurality of combinations of plating films can be continuously formed on the conductive member 21 by one transport rail regardless of the composition of the plating solution.

More specifically, the plating method of the solder plating line is the same as that of the first embodiment. For example, in the solder plating line of FIG. 2, the first plating bath 54 is filled with a Sn plating solution, and the second plating bath 55 is Sn: Bi = 98.
(% By weight): 2 (% by weight) of the plating solution
In the plating bath 56, Sn: Bi = 43 (% by weight): 57
(% By weight) of the plating solution. In these plating baths, a necessary plating bath is selected according to the use of the plated conductive member 21, and the plating solution in the plating bath that is not required moves to the plating solution storage bath.
As a result, Sn or Sn: Bi = 98 is applied to the conductive member 21.
(% By weight): 2 (% by weight) single-layer plating film is formed, or the first layer is Sn and the second layer is Sn: Bi = 43 (% by weight): 57 (% by weight) two-layer plating A film is formed or a two-layer plating of the first layer is Sn: Bi = 98 (% by weight): 2 (% by weight) and the second layer is Sn: Bi = 43 (% by weight): 57 (% by weight). A film or the like is formed.

In the second embodiment, the first conductive member 21
In order to form the plating film 22, a plating solution of Sn: Bi = 98 (% by weight): 2 (% by weight) can be used. At this time, when the plating solution contains about several% of Bi, the first plating film 22 has whiskers (needle-shaped crystals).
Is remarkably suppressed.

Therefore, in the present invention, a plating bath containing a plurality of plating solutions having different plating solution configurations, and a plating solution storage bath installed in the plating bath as necessary or in all cases. Then, the plating solution can be moved between both bathtubs according to the intended use of the conductive member 21. As a result, a plurality of combinations of plating films can be continuously formed on one transfer rail.

That is, a plurality of combinations of plating films can be continuously formed on the conductive member 21 by one transfer rail. This eliminates the need to temporarily stop the plating apparatus according to the combination of plating films and replace the plating solution in the bathtub. As a result, the working time can be significantly reduced, and the labor for replacing the plating solution can be omitted. Further, when the plating baths are exchanged in the same bath, the plating baths do not mix with each other, and the labor for the management of the plating baths and the maintenance of the plating bath, plating equipment and the like can be greatly reduced.

In addition, a plurality of combinations of plating films can be continuously formed on one transfer rail. For example, in the first plating bath, the plating solution is moved to the first plating solution storage bath, and the plating film is formed in the second and third plating baths. In the first and second plating baths, the plating solution is transferred to the first and second plating baths. There is a method of forming a single-layer plating film only in the third plating bath by moving the plating bath to the second plating bath. Also,
A thick plating film can be formed on the conductive member 21 by putting plating solutions of the same composition into adjacent plating baths.

In any case, as described above,
By moving the plating solution of the present invention between both bathtubs, it is possible to form a plurality of combinations of plating films continuously on one transport rail.

As described above, the case of solder plating has been described as an example, but this plating apparatus can be used not only for solder plating. For example, Sn plating, Cu
There are plating, Ni plating and the like. Also in these cases, a plurality of combinations of plating films can be formed on the conductive member 21 continuously using one plating rail by using this plating apparatus.

Next, as a second embodiment, referring to FIGS. 3, 4 and 7, a plating auxiliary rack having a rectangular parallelepiped structure centered on four main pillars and this plating auxiliary rack were used. The plating method will be described.

FIG. 3 is a layout simply showing a plating auxiliary rack for implementing the plating method of the present invention. FIG. 4 is a layout in which the conductive member 21 (see FIG. 7) installed in the plating auxiliary rack 72 shown in FIG. 3 is plated from the plating bath 71 from above. Here, in the electroplating, the conductive member 21 is mainly used.
Is described as a case where the electrode 73 is the anode 73 in order to make the electrode 73 a cathode.

According to the present invention, when a plating film is formed on the conductive member 21, a rectangular parallelepiped plating auxiliary rack 72 composed of four main pillars is used, so that any part of the conductive member 21 having a different surface area or the like can be used. It is characterized in that the current density is applied more uniformly.

More specifically, the plating solution has a current density range suitable for each plating solution when performing the plating operation, and a high quality plating film is formed by performing the plating operation within the range. be able to. In this plating method, the conductive member 21 is installed in a rectangular parallelepiped plating auxiliary rack 72 composed of four main pillars, and the plating auxiliary rack 72 is immersed in the plating solution in the plating bath 71. Since this plating auxiliary rack 72 is formed of a member made of a conductive material, it forms a cathode integrally with the conductive member 21. Then, as shown in FIG. 2, the conductive member 21 is installed so as to be located at the center of the plating auxiliary rack 72, so that the main column of the plating auxiliary rack 72 is located between the anode 73 and the conductive member 21. Will be. By doing so,
Most of the high current density parts are plated auxiliary racks 72.
Of the conductive member 21
To form a plating film. As a result, it is possible to form a plating film having a uniform plating film composition distribution and a uniform plating film thickness on various different conductive members 21 such as the conductive member 21 having a large surface area and the conductive member having a small surface area.

For example, a plating film may be formed on the conductive member 21 having a large surface area. Here, the plating solution has a current density in a range suitable for the plating solution. Since the surface area is large, there is also a difference in how the current density is applied between the center and the end of the conductive member 21. In this case, as described above,
When the main pillar of the plating auxiliary rack 72 enters between the conductive member 21 and the anode 73, the electric field adjustment in the plating solution is assisted so as to avoid most of the parts having a high current density.
As a result, the difference in current density between the center of the conductive member 21 near the anode 73 and the end of the conductive member 21 far from the anode 73 is reduced, and the surface of the conductive member 21 is uniformly plated with a uniform film thickness. A plating film having a film composition is formed.

The first layer of Pb-free plating is S
With n, a plated film of Sn—Bi may be formed as the second layer. At this time, the second Sn—Bi plating film is
It is plated in the range of about 1-5 μm. Here, if the plating is performed without using the plating auxiliary rack 72, the variation in the plating film thickness especially at the end and the center of the conductive member 21 in the thin Sn—Bi plating film due to the electroplating characteristics as described above. And some parts are not formed. However, by using the plating auxiliary rack 72, a plating film having a uniform plating film composition with a uniform film thickness is formed on the surface of the conductive member 21 without any unformed portion.

Here, a plating apparatus used in the plating method of the present invention will be described. In this plating apparatus, a plating auxiliary rack 72 made of a conductive material is used.
The auxiliary plating rack 72 has a rectangular parallelepiped shape composed of four main pillars. And, this plating auxiliary rack 72
Is located between the conductive member 21 and the anode 73 to assist in forming a plating film. At this time, the plating auxiliary rack 72 forms a cathode integrally with the conductive member 21 and assists in electric field adjustment in the plating solution so that a plating film having a uniform plating film composition with a uniform thickness is formed.

Therefore, in the plating method and the plating apparatus used therefor, when the plating film is formed on the conductive member 21, the plating auxiliary in the form of a rectangular parallelepiped formed of four main pillars made of a conductive material is used. A rack 72 is used. As a result, the plating auxiliary rack 72 forms a cathode integrally with the conductive member 21 and the plating auxiliary rack 7
Since the four main pillars 2 are located between the conductive member 21 and the anode 73, it is possible to prevent a portion having a high current density from directly covering the conductive member 21 to form a plating film. As a result, the electric field in the plating solution is adjusted with the assistance of the plating auxiliary rack 72, and a uniform current density is applied to all surfaces of the conductive member 21.

That is, by forming a plating film on the conductive member 21 using the plating auxiliary rack 72, it is possible to optimize the plating film thickness and the distribution of the plating film composition and to form a uniform plating film.

As described above, the case of solder plating has been described as an example, but this plating apparatus can be used not only for solder plating. For example, Sn plating, Cu
There are plating, Ni plating and the like. Also in these cases, a plating film can be formed on various types of conductive members 21 by using a plating apparatus used in this plating method under conditions suitable for a plating solution.

As described above, the embodiment in which the electrode 73 is the anode 73 has been described. However, even when the electrode 73 is the cathode 73, the conductive member 21 is formed by the same plating method.
A plating film can be formed on the substrate.

Finally, as a third embodiment, a method of plating a lead used in a semiconductor device will be described with reference to FIGS.

First, Cu alone, Cu alloy or Fe—N
The first plating on the surface of the conductive member 21 such as i-alloy
In the case where a plating solution containing Sn as a main metal material is plated on the plating film 22, a smooth film is formed on the surface of the first plating film 22, in particular. However, when two kinds of metals such as Sn-Bi are plated as the first plating film 22, the first plating film has a large ionization tendency.
i has a feature of being preferentially deposited. Due to this phenomenon,
The surface of the first plating film 22 is formed with non-smooth deposited particles.

As a result, when an operation of contacting the lead frame is added, the following problem occurs. For example, in the bending process, in the step of contacting the current-carrying terminals with the lead frame to determine the quality of the IC, the above-mentioned preferentially deposited non-smooth particles fall off, so that the dropped particles adhere between the leads. This leads to a defect. In addition, when the lead frame is transported, the frictional resistance of the surface of the lead frame is reduced, and the lead frame remains on the transport unit that comes into contact with the lead frame.

Here, the problem that occurs in the bending process will be specifically described. FIG. 5 is a schematic view of a mold for bending a lead frame. Then, as shown, the lead frame 82 of the semiconductor device 81 is cut and
Problems occur when bending.

First, a plated lead frame 8
2 are placed on the pedestals 84A and 84B, and the sealing body of the semiconductor device 81 and the lead frame 82 are fixed by the pedestal 84A and the lead supporting means 85. At this time, the lead frame 8
2 is set on the base 84B and the punch 83
Then, the lead frame 82 is cut, and the other portions are bent. At this time, the bottom surface of the punch 83 and the surface of the lead frame 82 come into contact with each other, and a phenomenon that coarsened precipitate particles adhere to the bottom surface of the punch 83 as debris or adhere to the lead lead frame 82 occurs.

In addition, the lead frame currently used has about 200 pins, and a narrow lead frame has 0.4 pins.
mm. Further, since the semiconductor device itself is significantly reduced in size, it is presumed that the adhered substance causes poor quality. For this reason, it is desirable in the semiconductor manufacturing process that the above-mentioned main metal material be plated with a plating solution composed of Sn alone or the like.

On the other hand, it has been found that a trace amount of Bi is mixed in the plating method in which the main metal is composed of Sn alone in the manufacturing method described below.

As described in the first embodiment, in the plating apparatus of the present invention, a plating solution can be freely selected, and the first plating film 22 of Sn alone is formed on the surface of the conductive member 21. It is possible to form. However, as described in the second embodiment, since the plating auxiliary rack 72 is used when plating the conductive member 21, a plating film is also formed on the surface of the plating auxiliary rack 72. And
The plating auxiliary rack 72 is subjected to cleaning and the like in a subsequent step, and the plating film of the plating auxiliary rack 72 itself is dropped.
The plating auxiliary rack 72 is repeatedly used in one transfer line. For this reason, an extremely small amount of Bi is mixed into the plating solution made of Sn alone.
Also, a very small amount of Bi
Are mixed as impurities. Therefore, Bi is mixed with Sn to some extent even in the plating solution of Sn alone. Actually, even though the first plating film 22 is a plating film made of Sn alone, there is a possibility that the first plating film 22 is formed as a semiconductor device in which a trace amount of Bi exists in the film.

Therefore, it was investigated how much Bi would enter the first plating film 22 to cause a problem. When Bi is contained in an amount of 0 to 0.5% by weight based on Sn, no precipitated particles are generated. Bi is 0.5 to Sn or less.
When it is contained in an amount of 1.0% by weight, coarsening of precipitated particles hardly occurs, but a very small amount may occur at a level that does not cause any problem. However, if Bi is contained in an amount of 1.0 to 3.0% by weight, a problematic level of coarsening of precipitated particles occurs. When the deposition particles are coarsened on the surface of the first plating film, the deposition particles are naturally coarsened also on the surface of the second plating film 23.

From this, the first plating film 22 is made of Sn
A single or less than 1% by weight (particularly 0 to 0.5% by weight) plating film is formed, and any concentration of Sn-B
It was found that the particles were not coarsened even if the i-plated film 23 was formed.

Hereinafter, in a semiconductor device using a lead frame, a semiconductor chip is mounted on the lead frame, and wiring is performed using thin metal wires. Thereafter, the lead that is sealed and exposed from the sealing portion is bent. The single semiconductor device is electrically measured via a lead and supplied to a user. Then, on the user side, it is fixed to the electrode on the mounting board via a brazing material.

Here, the plating process can be performed before mounting the semiconductor chip and after sealing. When plating is performed before mounting the semiconductor chip, it is necessary to perform a process so that a plating film is not applied to a connection portion of the thin metal wire. On the other hand, when the treatment is performed after the sealing, the metal conductive portion exposed from the sealing portion can be immersed in the plating chemical, and there is an advantage that selective deposition is unnecessary. Although the semiconductor device has been described as a circuit device, passive elements and composites thereof may be sealed. Further, as a sealing material, a thermoplastic or thermosetting resin, ceramic, or the like can be processed.

Further, the present invention can be applied to an electrode such as a CSP in which a semiconductor chip is fixed on a matrix on an electrode on a support substrate, then sealed, and then individualized. In this case, means capable of supplying current to all the electrodes is required.

[0061]

As is apparent from the above description, the plating apparatus of the present invention has the following effects.

The first effect is that this plating apparatus has a function of moving a plating solution between both baths in a solder plating line, so that a single layer or a combination of a plurality of layers can be continuously formed on one transport rail. Can be formed. Therefore, the plating solution is not changed every time the plating film formed on the conductive member is changed, and the plating apparatus is not temporarily stopped. As a result, a plurality of combinations of plating films can be continuously formed on the conductive member by one transfer rail, so that the working time can be significantly reduced, and the labor for replacing the plating solution is eliminated. Can be. Further, when the plating solutions are exchanged in the same bath tub, the respective plating solutions are not mixed with each other, so that the labor for the management of the plating solution and the maintenance of the plating bath tub and the plating equipment can be greatly reduced.

As a second effect, by performing the plating operation according to the plating method of the present invention, it is possible to release most of the strong current density from the conductive member to various conductive members having different surface areas and the like. it can. By doing so,
For conductive members with different surface areas and designs, the current density within the preferred range of the plating solution used, the electric field in the plating solution is controlled, and the current density is uniformly applied to all surfaces of the conductive member Become like as a result,
It is possible to optimize a plating film thickness and a plating film composition distribution and form a uniform plating film for various conductive members.

The third effect is that the plating apparatus used in this plating method uses a plating auxiliary rack having a rectangular parallelepiped shape composed of four main pillars made of a conductive material. It is possible to form a high-quality plating film on various conductive members having different characteristics.

A fourth effect is that in a method of manufacturing a semiconductor device in which a plurality of plating films are formed on the surface of a conductive member such as a simple substance of Cu, a Cu alloy or an Fe—Ni alloy,
The first plating film is made of a Sn-Bi metal material, particularly a trace amount of B
A plating film is formed by using a plating solution containing Sn as a main metal material in which i is mixed, but no deposition particles are generated on the surface of the first plating film, or even if it is generated, extremely fine deposition particles are formed. A method for manufacturing a semiconductor device having a certain good plating film can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a plating line used in a plating apparatus of the present invention.

FIG. 2 is a diagram illustrating a plating line used in the plating apparatus of the present invention.

FIG. 3 is a diagram illustrating a plating auxiliary rack used in the plating apparatus of the present invention.

FIG. 4 is a layout viewed from the top where a plating operation is performed in a plating bath used in the plating apparatus of the present invention.

FIG. 5 is a diagram illustrating a method for manufacturing a semiconductor device according to the present invention.

FIG. 6 is a diagram illustrating a semiconductor chip to be plated according to the present invention and a conventional method.

FIG. 7 shows the present invention and the conventional two-layer plating film shown in FIG.
FIG. 4 is a diagram illustrating a cross section of the semiconductor lead frame shown in FIG.

FIG. 8 is a diagram illustrating the layout of the present invention and the entirety of a conventional automatic plating apparatus.

9 is a diagram illustrating a cross section of the chemical etching bath of the entirety of the present invention and the conventional automatic plating apparatus shown in FIG.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/50 H01L 23/50 D

Claims (16)

[Claims] 1. A plating apparatus having a plating pretreatment line and a plating line, wherein the plating line has a plurality of plating baths, and a plating solution storage bath is provided in a desired plating bath. Plating equipment. 2. A plating apparatus having a plating pretreatment line and a plating line, wherein the plating line has a plurality of plating baths, and a plating solution storage bath is provided in each of the desired plating baths. And plating equipment. 3. A plating film is formed on a conductive member in the plating bath of the plating line.
Alternatively, the plating apparatus according to claim 2. 4. The plating apparatus according to claim 1, wherein the plating solution storage bath is provided at a position lower than the plating bath. 5. The plating apparatus according to claim 1, wherein the plating bath is connected to the plating solution storage bath by a pipe, and the plating solution is moved through the bath. 6. In the plating line, in the plating bath in which the conductive member is not immersed, the plating solution is moved to the corresponding plating solution storage bath to prevent the conductive member from being immersed in the plating solution. 3. The plating apparatus according to claim 1, wherein a plurality of combinations of plating films are formed on the member. 7. A plating method for arranging an electrode for supplying current and a conductive member on which a plating film is formed in a plating bath containing a desired plating solution and applying a current to form a plating film, wherein a current flowing from the electrode is provided. A plating method comprising: setting a density within an optimum current density range of the plating solution; installing the conductive member on a plating auxiliary rack; and then forming a plating film on the conductive member. 8. The plating method according to claim 7, wherein the plating auxiliary rack is used integrally with the conductive member as another electrode different from the electrode. 9. The plating method according to claim 7, wherein the plating auxiliary rack is positioned between the electrode and the conductive member to adjust a plating film thickness and a plating film composition distribution. 10. A plating apparatus for forming a plating film with an electrode for supplying a desired plating solution and a current in a plating bath and a conductive member provided on a plating auxiliary rack, wherein the plating film is formed of a conductive material. A plating apparatus, wherein a plating film is formed by installing the conductive member in a plating auxiliary rack. 11. The plating apparatus according to claim 10, wherein the plating auxiliary rack has a rectangular parallelepiped shape centered on four main pillars. 12. A first plating film layer made of Sn as a main metal material is formed on a lead mainly made of Cu or Fe-Ni, and a plating film made of Sn-Bi as a main metal material is formed on the outermost surface of the lead. In the method for manufacturing a semiconductor device, wherein a layer is formed and the lead is fixed to a conductive means via a brazing material, the first plating film layer contains about 0 to 1% by weight of Bi with respect to Sn. A method for manufacturing a semiconductor device, comprising: 13. The Bi is 0 to 0.5 with respect to Sn.
13. The method of manufacturing a semiconductor device according to claim 12, wherein the amount is about 10% by weight. 14. A lead mainly composed of Cu or Fe—Ni is prepared, a circuit device is electrically connected to the lead, and the lead is sealed with a sealing body so that a part of the lead is exposed. A method for manufacturing a semiconductor device, comprising: bending the lead exposed from the sealing body, or electrically measuring the lead through the lead, and fixing the lead to conductive means via a brazing material. Has Sn as a main metal material,
A first plating film layer containing about 0 to 1% by weight of Bi with respect to the first metal layer, and a plating film layer containing Sn-Bi as a main metal material is formed on the outermost surface; Device manufacturing method. 15. The method according to claim 14, wherein the lead is prepared by performing a plating process. 16. The method for manufacturing a semiconductor device according to claim 14, wherein a plating process is performed on the leads exposed from the sealing body after sealing with the sealing body.