JP2004165692A - Method for manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a plurality of combined plated-film through one transferring rail continuously; to form a plated-film having high quality and uniform film thickness on a lead frame and lead surface. <P>SOLUTION: A plurality of plating baths 44, 45, 46 are located below the transferring rail in the plating facility. A plating-liquid containing baths 49, 50 are joined to the plating baths 45, 46 by a liquid transferring means 48. The plating liquid is transferred through the plating baths 45, 46 and the plating-liquid containing bath 49, 50 consequently, the plated film formed on a conductive component can be selected. Therefore, a plurality of combined plated-film can be formed on the conductive component through one transferring rail 42 continuously. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a method for manufacturing a semiconductor device in which at least two plating films are formed on a lead frame.

  In a conventional semiconductor device, a first plating film made of, for example, Sn alone and a Sn alloy made of a Sn alloy containing at least one selected from Ag, Bi, Cu, In, and Zn are formed on the surface of a conductive substrate. Two plating films are formed. Then, a structure in which the soldering temperature of the first plating film is higher than the soldering temperature of the second plating film and excellent in solderability is disclosed (for example, see Patent Document 1).

  Further, in the conventional method for producing a multilayer plated steel sheet, a method for producing a multilayer plated steel sheet having excellent appearance uniformity in which different types of metals are successively plated on Sn plating with respect to an electric tin plate using an insoluble anode. Is disclosed (for example, see Patent Document 2).

  Hereinafter, the plating apparatus will be described with reference to FIGS.

  FIG. 7 is a cross-sectional view taken along the line AA of the semiconductor lead frame shown in FIG. For example, the conductive member 21 is made of a Cu-based alloy or an Fe-Ni-based alloy. The surfaces of the conductive members 21 are plated with two layers of different materials.

  FIG. 8 is a layout of the entire automatic plating apparatus. First, in the alkaline electrolytic cleaning bath 31, a pretreatment is performed on the surface of the conductive member 21 to remove organic contaminants that hinder the adhesion and solderability of the solder plating film. Next, after the conductive member 21 is washed in the washing bath 32, a chemical etching process (basically, a process using an oxidation-reduction reaction) is performed in the chemical etching bath 33.

  Next, after the conductive member 21 is 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 a rinsing bath 36, a plating process is performed by a solder plating device 37. Since the solder plating solution is strongly acidic, the surface of the plating film after the plating process is acidic. On such a surface, the plating film discolors over time, and the solderability deteriorates. Therefore, in the washing bath 38 and the neutralization bath 39, the acid remaining on the plating film surface is neutralized, and the adsorbed organic matter is removed. After that, the conductive member 21 is washed in a water bath 40 and a hot water bath 41, and dried in a drying device 42.

  FIG. 9 is a cross-sectional view of the chemical etching bath 33 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. The upper limit position and the lower limit position of the movable range are determined, and the movable range is repeatedly moved. The hanging hooks 333 are hung on the transport rail 332 at appropriate intervals according to the work purpose. It is usually the distance between the centers of adjacent bathtubs. Then, the plating auxiliary 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 lateral 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 returns by that amount when the hanging hook 333 is sent one span in the working direction. In the lateral feed type pusher 331, the transport rail 332 is at the upper limit position, the hanging hook 333 is sent by one span, the transport rail 332 is at the lower limit position, and the horizontal feed type pusher 331 is returned by that amount. . 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.
JP-A-10-229152 (page 3-4, FIG. 1) JP-A-7-305193 (page 6-12, FIG. 1)

  When an alloy plating film having a different ionization tendency, such as Sn metal and Bi metal, is formed on the surface of a conductive member such as a lead frame, Bi having a high ionization tendency is preferentially deposited. Due to this phenomenon, the surface of the first plating film is formed with non-smooth deposited particles, and even when the second plating film is formed on the surface of the first plating film, the surface of the first plating film becomes non-smooth due to the deposited particles. This results in the formation of a plating film surface.

  If, for example, the lead is bent in a state where the surface of the lead frame subjected to the plating treatment is a non-smooth plating film surface, the precipitated particles fall off, and the dropped particles adhere between the leads. Then, in the step of contacting the current-carrying terminals with the leads and determining the quality of the IC, there was a problem that particles adhering between the leads were determined to be defective.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and in a method of manufacturing a semiconductor device according to the present invention, a first lead made mainly of Cu or Fe-Ni is made of Sn metal as a main metal material. A method of manufacturing a semiconductor device in which a plating film is formed, a second plating film made of an alloy of the Sn metal and the Bi metal is formed on the outermost surface of the lead, and the lead is fixed to conductive means. The plating film includes the Bi metal in an amount of about 0 to 1% by weight based on the Sn metal. Therefore, in the method of manufacturing a semiconductor device according to the present invention, the plating solution for forming the first plating film layer is formed on the plating film surface by including about 0 to 1% by weight of Bi with respect to Sn. Deposited particles can be suppressed.

  In the method of manufacturing a semiconductor device according to the present invention, a lead mainly composed of Cu or Fe-Ni is prepared, a circuit device is electrically connected to the lead, and sealing is performed so that a part of the lead is exposed. In the method of manufacturing a semiconductor device in which the lead is fixed to a conductive means by sealing with a stopper, Sn metal is used as a main metal material on the surface of the lead, and about 0 to 1% by weight based on the Sn metal. A first plating film containing Bi metal is formed, and a second plating film made of an alloy of the Sn metal and the Bi metal is formed on the outermost surface. Therefore, in the method of manufacturing a semiconductor device according to the present invention, the plating solution for forming the first plating film layer is formed on the plating film surface by including about 0 to 1% by weight of Bi with respect to Sn. Deposited particles can be suppressed. Then, it is possible to prevent the precipitated particles from falling off due to bending of the lead or the like, and to reduce false recognition in IC determination.

  As a first effect, this plating apparatus has a function of moving a plating solution between both bathtubs. As a result, a single-layer or a combination of a plurality of plating films can be formed continuously by one transport rail. Further, 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. Thereby, a plurality of combinations of plating films can be formed on the conductive member continuously by one transfer rail. For this reason, the working time can be greatly reduced, and the labor for replacing the plating solution can be omitted. Further, when the plating solutions are exchanged in the same bathtub, the respective plating solutions do not mix with each other. Therefore, the labor for managing the plating solution and for maintaining the plating bath, plating equipment, and the like can be significantly reduced.

  As a second effect, by performing the plating operation by 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. As a result, it is possible to perform a plating process on conductive members having different surface areas and designs with a current density within a suitable range of a plating solution to be used. Further, the electric field in the plating solution is controlled, so that the current density is uniformly applied to all surfaces of the conductive member. 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.

  As a third effect, a plating auxiliary rack having a rectangular parallelepiped shape composed of four main pillars made of a conductive material is used. Thus, a high-quality plating film can be formed on various conductive members having different surface areas and the like.

  As a fourth effect, 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 Cu alone, a Cu alloy, or an Fe—Ni alloy, the first plating film is formed of Sn—Bi. A plating film is formed using a metal material, in particular, a plating solution containing Sn as a main metal material mixed with a trace amount of Bi. This makes it possible to realize a method of manufacturing a semiconductor device having no plating particles generated on the surface of the first plating film or having a favorable plating film that is extremely fine precipitated particles even if it occurs.

  First, as a first embodiment, a plating apparatus having a plating pretreatment line and a plating line will be described with reference to FIGS. 1, 2, and 7. FIG. The plating line has a plating bath for forming a plating film layer of a plurality of patterns, and the plating bath is provided with a plating solution storage bath.

  FIG. 1 is a layout schematically showing the functions of a plating line for implementing a plating apparatus according to the present invention. In this plating line, a pre-dip bath 43, a first plating bath 44, a second plating bath 45, a third plating bath 46, and a washing bath 47 are provided below the transport rail 42. 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) using these bathtubs. This mechanism is the same as the conventional one.

  The present invention is a mode in which a plating solution storage bath is provided as necessary in accordance with a plating bath. For example, as shown in FIG. 1, the first plating bath 44 does not include a plating solution storage bath. In the second plating bath 45, a first plating solution storage bath 49 is installed, and in the third plating bath 46, a second plating solution storage bath 50 is installed. In this case, in order to make efficient use of the work space and to store the plating solution in a short time when storing the plating solution, a plating solution storage bath (hereinafter referred to as a plating solution storage bath) is provided under the plating bath. A bathtub). Thus, in this plating line, a plurality of combinations of plating films can be continuously formed on the conductive member 21 by one transport rail.

  FIG. 2 is a layout schematically showing the function of a plating line for implementing the plating apparatus according to the present invention. In this plating line, a pre-dip bath 53, a first plating bath 54, a second plating bath 55, a third plating bath 56, and a washing bath 57 are provided below the transfer 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.

  And, storage tubs are installed for all plating tubs. For example, in FIG. 2, a first storage bath 59 is provided in the first plating bath 54, a second storage bath 60 is provided in the second plating bath 55, and a third storage bath 61 is provided in the third plating bath 56. Also in this case, as described above with reference to FIG. 1, the storage tub was provided below the plating tub. Thus, this plating line is characterized in that a plurality of combinations of plating films can be continuously formed according to the intended use.

  The first mode will be specifically described. The mechanism of transport of this plating line is the same as in FIG. 9 described above. For example, in the plating line of FIG. 1, the first plating bath 44 contains a Sn plating solution, the second plating bath 45 contains a Sn—Bi plating solution, and the third plating bath 46 contains Sn. -Ag plating solution is contained. A necessary plating bath is selected from these plating baths according to the intended use of the plated conductive member 21. On the other hand, in an unnecessary plating bath, the plating solution in the bath is moved to the storage bath. However, in this embodiment, the plating solution is always put in the first plating bath 44 containing the Sn plating solution, and the conductive member 21 is immersed in the Sn plating solution. 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 always contains the Sn plating solution, and the Sn plating film is formed on the conductive member 21. First, the surface of the conductive member 21 treated in the plating pretreatment line is removed in a pre-dip bath 43 and then immersed in a plating solution of Sn in a first plating bath 44. In the meantime, in the second plating bath 45 and the third plating bath 46, since the plating film is not formed on the conductive member 21, the plating solution in the bath moves to the first storage bath 49 and the second storage bath 50. The conductive member 21 having the Sn plating film formed in the first plating bath 44 is transported to the second plating bath 45 and the third plating bath 46. However, since the plating baths 45 and 46 do not contain a plating solution, no plating film is formed. Next, the surface of the conductive member 21 on which the plating film is formed is washed in a washing bath 47. As a result, a single-layer Sn plating film is formed on the conductive member 21.

  Second, a case where the first plating film 22 and the second plating film 23 are formed on the conductive member 21 will be described. First, since the first plating bath 44 always contains a plating solution of Sn, the first plating film 22 of Sn is formed on the conductive member 21. Then, a plating bath in which the second plating film 23 is to be formed is selected according to the intended use of the conductive member 21. Here, when forming the Sn—Bi second plating film 23 first, the Sn—Ag plating solution in the third plating bath 46 is moved to the second storage bath 50. When forming the second plating film of Sn—Ag, the plating solution of Sn—Bi in the second plating bath 45 is moved to the first storage bath 49, and the second plating bath 46 is moved from the second storage bath 50 to the third plating bath 46. The plating solution of Sn-Ag is returned. 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 of 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, and the metal material of the third plating bath 46 is Sn-Bi. The metal material of the plating solution is Sn-Ag. Since the solution except for the metal and the solvent for dissolving the metal has the same composition, a plating film can be formed continuously on the conductive member 21. However, the plating film may be formed on the conductive member 21 using plating solutions having different liquid compositions. At this time, a plating bath containing pure water is prepared between the plating baths, and the surfaces of the plated conductive members 21 are washed to prevent mixing of different plating solutions. When the 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.

  The second embodiment will be specifically described. For example, in the solder plating line of FIG. 2, the first plating bath 54 contains a plating solution of Sn, and the second plating bath 55 has a plating ratio of Sn: Bi = 98 (% by weight): 2 (% by weight). The third plating bath 56 contains a plating solution of Sn: Bi = 43 (% by weight): 57 (% by weight). A necessary plating bath is selected from these plating baths according to the use of the conductive member 21, and the plating solution in the unnecessary plating bath moves to the storage bath. As a result, a single-layer plating film of Sn or Sn: Bi = 98 (% by weight): 2 (% by weight) is formed on the conductive member 21, or the first layer is Sn and the second layer is Sn: Bi = 43 (%). (Wt%): 57 (wt%) of a two-layer plating film is formed, or the first layer is Sn: Bi = 98 (wt%): 2 (wt%) and the second layer is Sn: Bi = 43 (wt%). % By weight): Two-layer plating films of 57 (% by weight) are formed.

  In this embodiment, a plating solution of Sn: Bi = 98 (% by weight): 2 (% by weight) can be used to form the first plating film 22 on the conductive member 21. At this time, the generation of whiskers (needle-shaped crystals) in the first plating film 22 is significantly suppressed by including about several percent Bi in the plating solution.

  Therefore, in the present invention, a plating bath containing a plurality of plating solutions having different plating solution configurations, and a storage bath installed in the plating bath as needed or all. Then, the plating solution is moved to both the upper and lower baths 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 transport rail. Thus, conventionally, the plating apparatus is temporarily stopped in accordance with the combination of the plating films, but in the present invention, there is no need to replace the plating solution in the bathtub. As a result, the working time can be greatly reduced, and the labor for replacing the plating solution can be omitted. Further, conventionally, when the plating solutions are exchanged in the same bathtub, the respective plating solutions are mixed. However, in the present invention, as described above, the liquid composition is the same. Therefore, even if a plating solution is mixed, a change in the composition of the solution can be suppressed, and labor for managing the plating solution and maintaining a 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 storage bath, and when the plating film is formed in the second and third plating baths, or in the first and second plating baths, the plating solution is transferred to the first and second plating baths. There is a case where a single-layer plating film is formed only in the third plating bath by moving to the storage bath. In addition, 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 between both bathtubs, it is possible to continuously form a plurality of combinations of plating films 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, there are Sn plating, Cu plating, and Ni plating. Also in these cases, it is possible to form a plurality of combinations of plating films on the conductive member 21 continuously using one transport rail by using this plating apparatus.

  Next, a plating auxiliary rack having four main pillars and a rectangular parallelepiped structure and a plating method using the plating auxiliary rack will be described with reference to FIGS.

  FIG. 3 is a layout simply showing a plating auxiliary rack for performing the plating method of the present invention. FIG. 4 shows a layout in which the conductive member 21 (see FIG. 7) installed in the plating auxiliary rack 72 shown in FIG. 3 is immersed in the plating bath 71. Here, in the electroplating, since the conductive member 21 is mainly used as a cathode, the case where the electrode 73 is the anode 73 will be described.

  In the present invention, when forming a plating film on the conductive member 21, a rectangular parallelepiped plating auxiliary rack 72 composed of four main columns is used. This is characterized in that the current density can be applied more uniformly to various conductive members 21 having different surface areas and the like.

  Specifically, the plating solution has a current density range suitable for each plating solution when performing the plating operation. By performing the plating operation at a current density within the appropriate range, a high-quality plating film can be formed. Then, the conductive member 21 is placed on a rectangular parallelepiped plating auxiliary rack 72 composed of four main columns, and is immersed in the plating solution in the plating bath 71 together with the plating auxiliary rack 72. Since the plating auxiliary rack 72 is formed of a conductive material, it forms a cathode integrally with the conductive member 21. As shown in FIG. 4, 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 do. As a result, most of the portion having a high current density is directed to the main pillar of the plating auxiliary rack 72. On the other hand, a plating film is formed on the conductive member 21 in other places where the current density is weak. As a result, a plating film having a uniform plating film thickness and a uniform plating film composition distribution can be formed on various conductive members 21 having different surface areas, such as the conductive member 21 having a large surface area and the conductive member 21 having a small surface area. Can be.

  For example, a plating film may be formed on the conductive member 21 having a large surface area. When 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. However, as described above, since the main pillar of the plating auxiliary rack 72 enters between the conductive member 21 and the anode 73, the portion to be plated can avoid a portion 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. Then, a plating film having a uniform thickness and a uniform plating film composition is formed on the surface of the conductive member 21.

  Further, there may be a case where a Pb-free plating film is formed in which the first layer is Sn and the second layer is Sn-Bi. At this time, the second Sn—Bi plating film is plated in a range of about 1 to 5 μm. Here, plating is performed without using the plating auxiliary rack 72. In this case, due to the above-described electroplating characteristics, a variation in the plating film thickness occurs in the thin Sn—Bi plating film, particularly at the end and the center of the conductive member 21. Alternatively, a portion where the plating film is not formed occurs at the center of the conductive member 21. However, by using the plating auxiliary rack 72, a plating film having a uniform thickness and a uniform plating film composition is formed on the surface of the conductive member 21.

  Here, the plating apparatus of the present invention will be described. In this plating apparatus, a plating auxiliary rack 72 made of a conductive material is used. The plating auxiliary rack 72 is composed of four main pillars and has a rectangular parallelepiped shape. The plating auxiliary rack 72 has the conductive member 21 installed at the center and 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 adjusting the electric field in the plating solution so that a plating film having a uniform plating film composition with a uniform thickness is formed.

  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 plating film composition distribution and to form a uniform plating film.

  Further, as described above, the embodiment in which the electrode 73 is the anode has been described. However, even when the electrode 73 is the cathode, a plating film can be formed on the conductive member 21 similarly.

  Finally, a method for plating leads used in a semiconductor device will be described with reference to FIGS.

  First, in the first plating film 22 plated on the surface of the conductive member 21 such as Cu simple substance, Cu alloy or Fe—Ni alloy, when the plating solution in which the main metal material is Sn alone is plated, A smooth film is formed on the surface of the first plating film 22. However, when two kinds of metals such as Sn-Bi are plated as the first plating film 22, Bi having a high ionization tendency is preferentially deposited on the first plating film. Due to this phenomenon, the surface of the first plating film 22 is formed as a film with non-smooth precipitated particles.

  As a result, when an operation of contact between the lead frame and the processing device is added, a problem described below occurs. For example, in the bending step, there is a step of contacting a current-carrying terminal with a lead frame to determine the quality of an IC. In this step, the non-smooth particles preferentially precipitated fall off, and the dropped particles adhere between the leads. This may lead to a defect in the determination of the quality of the IC. In addition, when the lead frame is transported, there is a case where the frictional resistance of the surface of the lead frame is reduced and then the lead frame is rotated and stays on the transport unit that comes into contact with the lead frame.

  Here, a problem occurring in the bending process will be specifically described. FIG. 5 is a schematic view of a mold for bending a lead frame. As shown in the figure, a problem occurs when the lead frame 82 of the semiconductor device 81 is cut and bent by the punch 83.

  First, the plated lead frame 82 is placed on the pedestals 84A and 84B. Then, 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 leading end of the lead frame 82 is placed on the pedestal 84B. Then, the lead frame 82 is cut by the punch 83, 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 coarsened precipitate particles adhere to the bottom surface of the punch 83 as debris. Alternatively, a phenomenon in which the deposited particles adhere to the lead frame 82 occurs.

  Moreover, the lead frame currently used has about 200 pins, and the pitch of the lead frame is as narrow as 0.4 mm. In addition, since the semiconductor device itself is significantly reduced in size, it is presumed that the attached matter causes poor quality. For this reason, it is desirable in the semiconductor manufacturing process that the above-described 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 following manufacturing method.

  As described in the first embodiment, in the plating apparatus of the present invention, the plating solution can be freely selected, and the first plating film 22 of Sn alone can be formed on the surface of the conductive member 21. Is possible. 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. Then, the plating auxiliary rack 72 is subjected to cleaning or the like in a subsequent step, and the plating film of the plating auxiliary rack 72 itself is dropped. However, 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, an extremely small amount of Bi is mixed as an impurity into the anode used as the electrode 73. Therefore, Bi is mixed with Sn to some extent even in the plating solution of Sn alone. Actually, even if the first plating film 22 is a plating film made of Sn alone, there is a possibility that a very small amount of Bi exists in the film and the first plating film 22 is formed.

  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 with respect to Sn, no precipitated particles are generated. When Bi is contained in an amount of 0.5 to 1.0% by weight with respect to Sn, coarsening of precipitated particles hardly occurs. However, a small amount of precipitated particles may be generated at an acceptable level. On the other hand, when Bi is contained in an amount of 1.0 to 3.0% by weight relative to Sn, 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 on the surface of the second plating film 23.

  From this, if the first plating film 22 is formed of Sn alone or a plating film of 1% by weight or less (particularly 0 to 0.5% by weight), any concentration of Sn is formed on the first plating film 22. -It was found that the coarsening of the particles did not occur even if the Bi plating film 23 was formed.

  In the following, a semiconductor device using a lead frame generally mounts a semiconductor chip on the lead frame and performs wiring using a thin metal wire. Thereafter, the lead that is sealed and exposed from the sealing portion is bent. Then, the single semiconductor device is electrically measured via leads and supplied to the 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 a semiconductor chip, it is necessary to perform a process for preventing a plating film from being applied to a connection portion of a thin metal wire. On the other hand, when the treatment is performed after the sealing, the metal conductive part exposed from the sealing part 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, a passive element or a composite thereof may be sealed. In addition, as the sealing material, a thermoplastic or thermosetting resin, ceramic, or the like can be processed.

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

It is a figure explaining a plating line used for a plating device of the present invention. It is a figure explaining a plating line used for a plating device of the present invention. It is a figure explaining the plating auxiliary rack used for the plating device of the present invention. It is a layout which looked at the figure which performs plating work in the plating bathtub used for the plating device of the present invention from the top. FIG. 4 is a diagram illustrating a method for manufacturing a semiconductor device according to the present invention. It is a figure explaining the semiconductor chip which carries out the present invention and the conventional plating. FIG. 4 is a diagram illustrating a cross section of the semiconductor lead frame shown in FIG. 3 formed of the present invention and a conventional two-layer plating film as viewed from the AA direction. It is a figure explaining the layout of the present invention and the whole conventional automatic plating device. FIG. 6 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.

Claims (7)

A first plating film made of Sn metal as a main metal material is formed on a lead mainly made of Cu or Fe-Ni, and a second plating film made of an alloy of the Sn metal and Bi metal is formed on the outermost surface of the lead. Forming a semiconductor device, and fixing the lead to a conductive means.
The method of manufacturing a semiconductor device according to claim 1, wherein the first plating film contains the Bi metal in an amount of about 0 to 1% by weight based on the Sn metal. 2. The method according to claim 1, wherein the Bi metal is included in an amount of about 0 to 0.5% by weight based on the Sn metal. In a method for manufacturing a semiconductor device, wherein a two-layer plating film of a first plating film and a second plating film is formed on a surface of a lead, a first plating solution for forming the first plating film on the lead. Immersing the lead in a second plating solution for forming the second plating film, without washing the lead with water, with the first plating solution attached to the lead. The method for manufacturing a semiconductor device according to claim 1, wherein the method comprises: A lead mainly made 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. In a method of manufacturing a semiconductor device fixed to
A first plating film containing Sn metal as a main metal material and containing about 0 to 1% by weight of Bi metal with respect to the Sn metal is formed on the surface of the lead. A method of manufacturing a semiconductor device, comprising forming a second plating film made of an alloy with the Bi metal. 5. The method according to claim 4, wherein the first plating film and the second plating film are formed on the leads exposed from the sealing body. In a method for manufacturing a semiconductor device, wherein a two-layer plating film of a first plating film and a second plating film is formed on a surface of a lead, a first plating solution for forming the first plating film on the lead. Immersing the lead in a second plating solution for forming the second plating film, without washing the lead with water, with the first plating solution attached to the lead. A method for manufacturing a semiconductor device according to claim 4 or claim 5, wherein 5. The method according to claim 4, wherein the lead exposed from the sealing body is bent or an electrical measurement is performed via the lead. 6.

Images