JP2005015921A - Plating method, and plating device utilized therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plating method where the generation of defects caused by the interruption of the plating can be prevented, and to provide plating equipment utilized therefor. <P>SOLUTION: The plating method comprises: a stage where the product to be plated is introduced into a plating liquid charged to a plating tank; a stage (120) where a first application current for plating to the product to be plated is applied to perform plating to the product to be plated; a stage (130) where, on the interruption of the plating, a second application current with a current quantity smaller than that of the first application current is applied to the anode, so that, during the interruption of the plating, the generation in the defects of the plating in the product to be plated is prevented; and a stage (140) where, after the dissolution of the interruption in the plating, the second application current is converted into the first application current, and the plating is continued to the product to be plated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to plating on an integrated circuit element, and more particularly to a method for plating an integrated circuit element capable of preventing the occurrence of an undesired defect in a plated product due to plating interruption due to an error such as a momentary stop. Related to plating equipment.

  During the assembly process of an integrated circuit element such as a semiconductor element, a process of plating leads and the like is performed. The plating process is mainly performed by an electroplating method, and is performed in the process of plating tin on the lead. A plating process employing an electroplating method is mainly used for plating an alloy on a product to be plated, as disclosed in Patent Document 1.

  The plating process of semiconductor elements is performed in a large-scale continuous plating process in response to a request for assembling a large number of semiconductor elements. That is, a process of suspending the semiconductor element product subjected to the packaging process on a moving chain belt or the like and continuously moving the semiconductor element product and plating the lead of the semiconductor element product with tin or the like is performed. The plating equipment for such a plating process has a large number of plating tanks that are substantially subjected to the plating process arranged in a row, and the semiconductor element product is continuously passed through the plating tank by a chain belt. It is comprised so that a plating process can be performed.

  The plating equipment includes not only a plating tank but also a number of pre-treatment solution tanks arranged in a row in the front direction of the plating tank, such as a chemical deflash process, a rinse process, a descaling process, an activation process, etc. The solution tanks are arranged in a row, and a solution tank for rinsing is further provided between the solution tanks. In the subsequent direction of the plating tank, a solution tank and a drying unit for the rinsing process and the neutralization process are provided. Such various solution tanks and plating tanks are arranged in a row, and a semiconductor element product is continuously transferred to them by a chain belt to perform the entire plating process.

  However, when the plating process is performed in a series of continuous processes as described above, the plating process may be unexpectedly interrupted due to an error in the plating equipment, and the plating on the product or lead in which plating is in progress may be interrupted. Can occur. In such a case, the transfer of the product or the lead by the chain belt is interrupted, and there is a possibility that overplating or the like occurs in the product located in the plating tank. In order to prevent the occurrence of such overplating, most of the plating equipment that adopts the electroplating method is the anode of the plating tank when the emergency operation of the plating equipment is interrupted, that is, when the chain belt transfer is interrupted. The equipment is configured to interrupt the current supply to the.

  However, such interruption of the current supply may act as a cause of unexpected plating failure. For example, in the case of lead-free plating, bismuth is supplied to a plating solution supplied to a plating tank for tin plating. However, such bismuth is highly replaceable to metal, and when the current supply to the anode is interrupted, bismuth may stick to the product lead and the lead that was in the process of plating may be oxidized black. There is. The product leads located between the plating tanks are also exposed to the atmosphere, so that defects due to oxidation occur.

  In practice, the products that are located in the plating tank in the plating process are about 30 frames on a lead frame basis. If such an undesirable defect occurs, all 30 frames are manually collected and re-plated. Must be done. In such a re-plating operation process, all of the unnecessarily plated portions and oxidized portions on the lead and the like are peeled off and further rinsed, re-plated, etc., and this has a great adverse effect on the overall plating yield.

  Therefore, even if the plating equipment is interrupted momentarily or due to an error, it is effective to cause defects such as undesired plating or oxidation on the products or leads on which plating has progressed. There is a need for a method that can be prevented.

Korean Patent Application Publication No. 2001-0015412 Specification

  The technical problem to be solved by the present invention is that, for example, undesired plating or oxidation is applied to a product or lead in which plating has progressed even if an instantaneous interruption of operation of the plating equipment or an interruption of operation due to an error occurs. The present invention provides a plating method capable of effectively preventing the occurrence of defects and a plating equipment used therefor.

According to one means of the present invention for achieving the above technical problem, there is provided a plating method for preventing occurrence of defects due to plating interruption.
The plating method includes introducing a product to be plated into a plating solution placed in a plating tank, and applying a first applied current for plating the product to be plated to an anode immersed in the plating solution. A step of plating the product to be plated, and applying a second applied current having a current amount smaller than the first applied current to the anode when the plating is interrupted, so that the plating is interrupted during the plating interruption. Preventing the occurrence of plating defects in the product, and continuing the plating on the product to be plated by converting the second applied current to the first applied current after the interruption of plating is resolved. .

Here, the second applied current has a current amount of 5% to 40% compared to the first applied current.
The plating solution contains tin and bismuth, and a tin: bismuth plating layer is formed on the product to be plated by the plating.
According to one means of the present invention for achieving the above technical problem, there is provided a plating equipment used in a plating method for preventing occurrence of defects due to interruption of plating.

  The plating equipment includes a series of a plurality of main plating tanks into which a plating solution is placed, an anode immersed in the plating solution in the main plating vessel, and an auxiliary plating through which the plating solution flows. A tank corresponding to the anode, a transfer means for sequentially transferring the product to be plated to the main plating tank and the auxiliary plating tank, and a first application for plating the product to be plated to the anode. A power source for selectively applying a current and selectively applying a second applied current having a smaller current amount than the first applied current to the anode when the plating is interrupted.

Here, the plating equipment further includes an auxiliary anode installed in the auxiliary plating tank corresponding to the transfer means as the cathode passing through the auxiliary plating tank and connected to the power source. The auxiliary anode is connected to the anode connected to the power source and connected to the power source.
Alternatively, the anode extends into the auxiliary plating tank corresponding to the transfer means as a cathode passing through the auxiliary plating tank.

The plating equipment further includes a sensor installed in the auxiliary plating tank to sense the plating solution flowing into the auxiliary plating tank.
When the power source switches from the first applied current to the second applied current, the power source applies the second applied current in a current amount of 5% to 40% of the first applied current.
The method of using such plating equipment includes the step of continuously supplying the products to be plated to the plating equipment by the transfer means and passing the products to be plated through the main plating tank and the auxiliary plating tank, Applying a first applied current for plating to the product to be plated from a power source to the anode to advance the plating to the product to be plated, and from the first applied current from the power source when the plating is interrupted By applying a second applied current of a small amount of current to the anode, during the plating interruption, preventing the occurrence of defective plating of the product to be plated, and after the plating interruption is eliminated, Converting the second applied current to the first applied current and continuing to plate the product to be plated.

Here, the plating equipment further includes an auxiliary anode installed in the auxiliary plating tank, and the second applied current from the power source is applied to both the auxiliary anode and the anode. At this time, the first applied current from the power source is applied to both the auxiliary anode and the anode.
According to another means of the present invention, at least one product to be plated is immersed in at least one plating tank containing a plating solution, and at least one of the anodes immersed in the plating solution. Applying a current for plating to a product to be plated, reducing the plating current applied to at least one anode when the plating is interrupted, and after the plating interruption is eliminated, A plating method is provided that includes converting the plating current to a previous amount and continuing to plate the product to be plated. At this time, the plating current can be reduced from 5% to 40% of the original value.

  According to another means of the present invention, a series of a plurality of main plating tanks into which a plating solution is put, an anode immersed in the plating solution of the main plating tank, and the main plating tank are connected. An auxiliary plating tank through which the plating solution flows, a cathode corresponding to the anode, a transfer means for sequentially transferring the product to be plated to the main plating tank and the auxiliary plating tank, and the anode to the product to be plated. And a power source for reducing the current when the plating is interrupted.

  According to another means of the present invention, at least one plating tank in which a plating solution for plating at least one product to be plated is placed, and the plating solution for plating on the product to be plated And a power supply that selectively applies a second applied current having a smaller current amount than the first applied current when the plating is interrupted.

According to another means of the present invention, the step of plating at least one product to be plated that passes through at least one plating tank containing a plating solution for plating, and while the plating is interrupted, Reducing the first current for plating and converting it to a second current.
At this time, the second current may be low enough not to cause the plating and high enough not to cause substitution or deposition of the components of the plating solution.

  According to another means of the present invention, in order to prevent at least one main plating tank and at least one product to be plated from being exposed to the environment outside the plating solution, any one of the plating solutions is used. A plating equipment comprising: at least one auxiliary plating tank connected to the main plating tank so as to flow from one main plating tank.

  According to the present invention, even if the operation of the plating equipment is instantaneously interrupted or the operation is interrupted due to an error, defects such as undesired plating or oxidation occur in the product or lead on which the plating has progressed. It can be effectively prevented.

  According to the present invention, even when the plating process is momentarily stopped or interrupted due to the occurrence of an error or the like, it is possible to effectively prevent the occurrence of defective plating of a product to be plated, for example, a lead frame, which was being plated. Thereby, the request | requirement of a reprocessing work reduces and it can improve a production rate and an equipment operation rate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the embodiments of the present invention can be modified in various other forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.
In the embodiment of the present invention, a large number of plating tanks are arranged in series, the product to be plated is transferred by a transfer means such as a chain belt, and the equipment is instantaneously interrupted due to an error or the like in the plating equipment for performing plating. When transfer of the product to be plated is interrupted, the current applied to the plating solution in the plating tank through the anode is reduced, but an undesired metal substitution reaction occurs when the current is applied with the minimum amount of current. Effectively prevent.

  In addition, even if an instantaneous operation interruption occurs, in order to effectively prevent oxidation etc. from occurring on the product to be plated that was transferred by the chain belt, A plating solution is provided at a minimum so that the product to be plated is maintained in the plating solution in a substantial plating process. For this purpose, an auxiliary plating tank is introduced between the plating tanks, and the plating equipment is configured so that the plating solution is also provided to the auxiliary plating tank. At this time, the auxiliary anode is also introduced into the auxiliary plating tank, and a minimum current is applied to the plating solution through the auxiliary anode so as to prevent the metal substitution reaction when instantaneous stop or instantaneous interruption of operation.

  According to such an embodiment of the present invention, even if an undesired momentary operation interruption or plating interruption of the plating equipment or the transfer chain belt occurs, an undesirable metal substitution reaction and exposure of the product to be plated to the atmosphere. It is possible to effectively prevent oxidation due to. Thereby, it is possible to effectively prevent occurrence of defects such as excessive plating, undesired metal substitution reaction, oxidation, etc. in the product to be plated due to undesired interruption of plating.

FIG. 1 is a flow diagram schematically illustrating a plating method according to an embodiment of the present invention. 2 to 6B are diagrams schematically illustrating plating equipment used in a plating method according to an embodiment of the present invention.
Referring to FIG. 1, in a plating method according to an embodiment of the present invention, when a plating process is momentarily interrupted due to an undesired error or the like, a product to be plated which is located in a plating tank and is being plated, In order to prevent excessive plating from progressing to the leads of the integrated circuit element and to prevent the occurrence of such an undesirable metal substitution phenomenon, the current applied to the plating solution in the plating bath is the current applied for plating. Compared to a small amount.

  For example, if the plating process is interrupted due to a plating equipment error, etc., the application of current for plating to the product to be plated is temporarily applied. Interrupted. When the current for plating is continuously supplied, the product to be plated, which has been transferred by a transfer means such as a chain belt, stops at a certain position and is kept immersed in the plating solution. Since the plating reaction is continuously performed, the plating layer is plated more than the required thickness for the product to be plated. In order to prevent this, the supply of the applied current applied for plating must be interrupted.

However, the bismuth atoms present in the plating solution when the supply of the applied current for plating is interrupted tend to spontaneously substitute for other metals and precipitate. As a result, bismuth may be substituted and deposited on the product to be plated or other metal parts in the plating tank, which may cause an undesirable defect.
In order to prevent this, in the embodiment of the present invention, when the plating process stops instantaneously, the first applied current for plating applied to the plating solution in the plating tank is converted into a relatively small second applied current. While the plating process is momentarily interrupted, the second applied current is continuously applied to the plating solution. That is, the second applied current is continuously applied to prevent the bismuth atoms from being deposited on the plating solution through the plating solution through the product to be plated (that is, the cathode) and the anode.

  The second applied current is not high enough to induce plating. However, the second applied current is merely a current that induces a metal element included in the plating solution that has a strong tendency to substitutional precipitation, that is, bismuth not to be substitutionally deposited. The amount is sufficient. For example, if the first applied current for plating is about 75A to 100A, the second applied current for preventing metal displacement deposition may be about 5A to 30A. That is, the second applied current may be about 5% to 40% compared to the first applied current. Preferably, the second applied current is applied to about 15A when the first applied current is 75A.

An example of an actual mass production process in which a plating tank is arranged and a product to be plated is sequentially transferred and plated in a plating equipment in which a large number of various purpose solution tanks are arranged before and after the plating tank. Examples of the present invention will be described more specifically.
2 and 3 are referred to together with FIG. FIG. 2 is a view schematically showing plating equipment used in a plating method according to an embodiment of the present invention, and FIG. 3 is a plating tank and auxiliary plating tank constituting the plating equipment according to an embodiment of the present invention. It is a top view which shows roughly.

  As schematically shown in FIG. 2, a large number of plating tanks 300 are arranged in series in the plating equipment, and a solution tank 250 in which various processes are performed is arranged before and after the plating tank 300. A product to be plated, that is, a lead frame in which a semiconductor element is packaged, is sequentially and continuously transferred to the plating tank 300 and the solution tank 250 by a transfer means such as a chain belt. Is done.

  The product to be plated is put on the chain belt at the mounting portion 210 and is put into the plating equipment. By the transfer of the chain belt, the product to be plated is first subjected to a chemical deflash process, followed by rinsing and high-pressure rinsing and then descaling. Next, after a rinsing step and an activation step, that is, after being immersed in a solution containing an activator, a pre-dip step is performed in the pretreatment solution tank 270. The turn wheel serves to change the transport direction of the chain belt. After being transferred to the plating tank 300 through the pre-dip process and plated, it is pulled out by the desorption part 230 through a neutralization process, a high-temperature rinse, an air injection and a drying process. At this time, it can be understood that the substantial plating process is performed when the product to be plated passes through the plating tank 300.

  As shown in FIG. 3, the plating tank 300 for performing the plating process shown in FIG. 2 may include main plating tanks 310, 320, 330, and 340 and an auxiliary plating tank 400. The auxiliary plating tank 400 is introduced through a connecting portion 350 that connects the main plating tanks 310, 320, 330, and 340, so that the plating solution also flows through the portion between the main plating tanks 310, 320, 330, and 340. To play an acceptable role. That is, the product to be plated that is dropped on the chain belt 500 and is immersed in the plating solution is separated from the plating solution between the main plating tanks 310, 320, 330, and 340 and is not exposed to the atmosphere. Therefore, the auxiliary plating tank 400 and the main plating tanks 310, 320, 330, and 340 are connected to each other so that the plating solution is also provided to the auxiliary plating tank 400. Accordingly, the plating solution provided to the main plating tanks 310, 320, 330, and 340 can flow into the auxiliary plating tank 400.

  After introducing the main plating tanks 310, 320, 330, and 340 and the auxiliary plating tank 400 in this way (110 in FIG. 1), the product to be plated is continuously transferred to perform plating (120 in FIG. 1). At this time, a current for plating is supplied to the anode 700 introduced into the main plating tanks 310, 320, 330, and 340 and the product to be plated suspended from the chain belt 500 through the power source 600 for the plating reaction. Applied. As such an applied current, a high current of about 75 A to 100 A is applied by a power source 600 including a rectifier to induce a plating reaction.

  FIG. 3 schematically shows the application of such a plating current. A plating current is applied to each of the anodes 700 introduced into the main plating tanks 310, 320, 330, and 340 in a plate shape (130 in FIG. 1). The power source 600 contacts the chain belt 500, and the product to be plated, that is, the lead frame that is electrically connected to the chain belt 500 and hangs down on the chain belt 500, serves as a cathode.

The metal element contained in the plating solution is plated on the product to be plated by the applied plating current. In the case of lead-free tin plating, the plating solution contains a tin element and a bismuth element, and tin and bismuth are plated on the product to be plated at a constant rate by such an applied plating current to form a plating layer.
However, there is a possibility that the plating process may be momentarily stopped or interrupted due to various types of errors during the plating process. Since the transfer of the chain belt 500 is interrupted by such a momentary stop or the like, the product to be plated remains immersed in the plating solution and continues to be stopped during the interruption period.

  In such a case, if the product to be plated is still in the plating solution under the supply of plating current, excessive plating may occur in the product to be plated. Since such excessive plating defects must be eliminated, when an instantaneous stop or interruption of the plating process occurs, the power source 600 interrupts the supply of the plating current, and the product to be plated through the anode 700 and the chain belt 500, That is, a second applied current smaller than the first applied current, which is a plating current, is applied to the cathode (130 in FIG. 1).

  Such a change in power supply from the first applied current to the second applied current is instantaneously interrupted in the plating process by a program set by a control unit (not shown) that controls the overall plating equipment. It happens automatically when it occurs. The second applied current is applied with a current amount that is about 5% to 40% smaller than the first applied current. That is, when the first applied current is 75A to 100A, the second applied current is applied to about 5A to 30A. Preferably, the second applied current may be 15A when the first applied current is 75A.

The conversion of the first applied current for plating applied to the plating solution to the second applied current smaller than this is for two large purposes.
First, the plating reaction of the product to be plated immersed in the plating solution is prevented from being activated, and the plating reaction is continuously performed to increase the thickness of the plating layer excessively. It is for preventing. Since the current amount of the plating current acts as one element for determining the plating amount by the plating reaction, it is possible to substantially prevent the plating reaction from proceeding to the product to be plated by reducing the current amount.

  Secondly, as in the case of lead-free tin plating, when the plating solution contains a metal element having a strong substitution tendency with respect to a metal such as bismuth, if the supply of the first applied current is interrupted, the bismuth atoms are changed. Displacement deposition is performed on the anode 700 or the product to be plated. Since this is an undesirable phenomenon in the plating process, it can be understood as a defect. However, as in the embodiment of the present invention, when a second applied current having a smaller current amount than the first applied current required for plating is applied through the anode 700 or the like, substitution deposition of bismuth atoms is caused. Is prevented.

  However, as shown in FIG. 3, the anode 700 installed in the main plating tanks 310, 320, 330, and 340 does not extend to the auxiliary plating tank 400. Therefore, some undesired phenomenon may occur in the product to be plated located at the position of the auxiliary plating tank 400, that is, the connecting part 350 between the main plating tanks 310, 320, 330, and 340 when the plating process is stopped. There is sex. For example, when an Sn: Bi plating solution is used, the Sn: Bi composition ratio of the plating layer varies. This is an undesirable phenomenon in the characteristics of the plating layer.

  In order to prevent such composition variation of the plating layer, a plate-like auxiliary anode 750 is introduced into the auxiliary plating tank 400 as shown in FIGS. 4, 5A and 5B. FIG. 4 is a plan view schematically showing the state of electrodes installed in the main plating tanks 310, 320, 330, and 340 and the auxiliary plating tank 400 constituting the plating equipment according to an embodiment of the present invention. FIG. 5A is a schematic view schematically illustrating a current application state in the main plating tanks 310, 320, 330, and 340 according to an embodiment of the present invention, and FIG. 5B is an auxiliary plating tank according to an embodiment of the present invention. 4 is a schematic diagram schematically showing a current application state at 400. FIG.

  Referring to FIG. 4, the auxiliary plating tank 400 is introduced through the connecting part 350 so as to connect the first main plating tank 310 and the second main plating tank 320, for example. Since the region of the first main plating tank 310 is substantially up to the plating liquid partition 311 introduced into the first main plating tank 310, the plating liquid provided in the first main plating tank 310 is the plating liquid partition 311. It will be put in the state. The plating liquid partition 311 is provided with a drain (not shown) for discharging the plating liquid in an outer space thereof.

  Accordingly, the auxiliary plating tank 400 is introduced so as to reach a substantial area of the first main plating tank 310, that is, an area where the plating liquid is placed, and the plating liquid put in the first main plating tank 310 is introduced. It flows into the auxiliary plating tank 400. Therefore, as shown in FIGS. 5A and 5B, when an instantaneous interruption of the plating process such as interruption of the transfer of the chain belt 500 occurs, the product to be plated is located in the auxiliary plating tank 400 and stops at that position. 550 is maintained in a state immersed in the plating solution 390 flowing into the auxiliary plating tank 400.

  At this time, the auxiliary anode 750 is introduced into the auxiliary plating tank 400. The auxiliary anode 750 may be introduced in a plate shape having a length comparable to the length of the auxiliary plating tank 400. Such an auxiliary anode 750 is introduced in order to prevent a defective metal product such as a bismuth element, which has a strong metal displacement precipitation characteristic, from sticking to the product to be plated 550 remaining in the auxiliary plating tank 400. . Accordingly, the auxiliary anode 750 may be connected to the power source 600 in common with the main anode 700 introduced into the first main plating tank 310 and the like. As a result, when the plating process is momentarily stopped or interrupted, the second applied current that prevents substitution deposition of metal elements is applied to the auxiliary anode 750 as well as the main anode 700.

Of course, the main anode 700 may be extended in the auxiliary plating tank 400 to a length in which the auxiliary plating tank 400 extends so that the main anode 700 can also serve as the auxiliary anode 750.
By introducing the auxiliary anode 750 into the auxiliary plating tank 400, substitutional deposition of bismuth is prevented, and it is possible to effectively prevent the composition ratio of the plating layer of the product to be plated from fluctuating due to the interruption of plating.

  On the other hand, as shown in FIG. 5B, the plating solution 390 flows into the auxiliary plating tank 400, so that the product to be plated 550 is continuously immersed in the plating solution 390 during the series of plating steps shown in FIG. Can be maintained and transported. Therefore, there is no possibility that the product to be plated 550 is exposed to the atmosphere even when the plating is interrupted. Therefore, it is possible to effectively prevent the product to be plated 550 that was being plated from being exposed to the atmosphere and oxidized.

Furthermore, the introduction of the auxiliary plating tank 400 is achieved by, for example, interconnecting four mutually separated main plating tanks 310, 320, 330, and 340 to distribute the plating solution 390, resulting in one large plating tank. A plating effect equivalent to the case of introducing 300 can be realized. That is, the uniformity of plating can be further improved.
When the auxiliary plating tank 400 is not introduced, an effect that the plating is interrupted occurs between the main plating tanks 310, 320, 330, and 340. When the auxiliary plating tank 400 is introduced, since the first applied current, which is a plating current, can be applied through the auxiliary anode 750 in a normal state where the plating process is not interrupted, the plating reaction continues to the product to be plated 550 during the transfer. It is done. This means that the disadvantages caused by the fact that the main plating tanks 310, 320, 330, and 340 can only be separated due to the characteristics of the equipment can be overcome.

  In fact, the individual main plating tanks 310, 320, 330, and 340 are very long to about 1.5 m, so that the entire plating tank 300 has a length of 6 m or more. It is practically very difficult to configure this with a single plating tank. However, by introducing the auxiliary plating tank 400, the separated main plating tanks 310, 320, 330, and 340 can actually realize a plating effect equivalent to that when a single plating tank is introduced.

Meanwhile, the auxiliary plating bath 400 may be configured as shown in FIGS. 6A and 6B. 6A and 6B are a perspective view and a side view schematically showing an auxiliary plating tank constituting the plating equipment according to an embodiment of the present invention.
Referring to FIGS. 6A and 6B, the auxiliary plating tank 400 may be configured such that two plate-like walls 410 are erected on the bottom plate 420. Legs 430 for support are attached to the bottom plate 420, and the two standing walls 410 can be supported on the bottom plate 420 by the support portion 460. A hole 440 is introduced into one wall 410, and a sensor 470 that detects the presence or absence of a plating solution is introduced into the hole 440. Such sensing of the plating solution is essential for proper supply of the plating solution.

  The wall length of the auxiliary plating tank 400 is such that when the auxiliary plating tank 400 is introduced between the main plating tanks 310 and 320 as shown in FIG. 3 or 4, the auxiliary plating tank 400 is at least the main plating tanks 310 and 320. It must have a length enough to reach the plating solution put in. That is, the wall 410 of the auxiliary plating tank 400 is configured to have a length that allows the auxiliary plating tank 400 to pass through the plating liquid partition (311 in FIG. 4) or to match the plating liquid partition. Is desirable.

  Referring to FIG. 1, when the instantaneous interruption or stop of the plating is eliminated, the second applied current is converted to the first applied current that is a plating current and applied to the main anode 700 or the auxiliary anode 750. The plating process is further continued (140 in FIG. 1). In such a case, as described above, during the instantaneous interruption or stop period of plating, plating defects such as excessive plating, metal displacement deposition or oxidation can be effectively prevented in the product to be plated. It is no longer necessary to reprocess the product to be plated that has remained in the plating solution when the plating process is momentarily interrupted. Actually, plating failure did not occur in the product to be plated even when the plating was interrupted for about 2 minutes. Therefore, the yield of the plating process and the operation rate of the plating equipment can be greatly improved.

The present invention has been described in detail through specific embodiments. However, the present invention is not limited thereto, and it is apparent that modifications and improvements can be made by those skilled in the art within the technical idea of the present invention. .
(Industrial applicability)
The present invention can be used for assembling a package of an integrated circuit device such as a semiconductor device. In particular, it can be used to plate the leads of a semiconductor device package.

It is a flowchart which shows the plating method by the Example of this invention roughly. 1 is a schematic view schematically showing plating equipment used in a plating method according to an embodiment of the present invention. 1 is a plan view schematically showing a main plating tank and an auxiliary plating tank constituting a plating equipment according to an embodiment of the present invention. FIG. 4 is a plan view schematically showing electrodes installed in a main plating tank and an auxiliary plating tank constituting a plating apparatus according to an embodiment of the present invention. It is a schematic diagram which shows roughly the electric current application state in the main plating tank which comprises the plating equipment by the Example of this invention. It is a schematic diagram which shows roughly the electric current application state in the auxiliary plating tank which comprises the plating equipment by the Example of this invention. 1 is a perspective view schematically showing an auxiliary plating tank constituting plating equipment according to an embodiment of the present invention. It is a side view which shows roughly the auxiliary plating tank which comprises the plating equipment by the Example of this invention.

Explanation of symbols

  270 Pretreatment solution tank, 300 Plating tank, 310, 320, 330, 340 Main plating tank, 311 Plating liquid partition, 350 connection part, 390 plating liquid, 400 Auxiliary plating tank, 470 Sensor, 500 Chain belt, 550 Product to be plated 600 power supply, 700 main anode, 750 auxiliary anode

Claims (22)

Introducing the product to be plated into the plating solution in the plating tank;
Plating the product to be plated by applying a first applied current for plating to the product to be plated to the anode immersed in the plating solution;
When the plating is interrupted, the second applied current having a smaller current amount than the first applied current is applied to the anode, thereby preventing the occurrence of plating failure of the product to be plated while the plating is interrupted. And the stage of
After the interruption of the plating is eliminated, converting the second applied current to the first applied current and continuing to plate the product to be plated;
The plating method characterized by including.   2. The plating method according to claim 1, wherein the second applied current is a current amount of 5% to 40% as compared with the first applied current.   The plating method according to claim 1, wherein the plating solution contains tin and bismuth, and a tin: bismuth plating layer is formed on the product to be plated by the plating. A series of a plurality of main plating tanks containing the plating solution;
An anode immersed in the plating solution of the main plating tank;
An auxiliary plating tank that connects between the main plating tanks and the plating solution flows;
A cathode corresponding to the anode, a transfer means for sequentially transferring products to be plated to the main plating tank and the auxiliary plating tank;
A first applied current for plating the product to be plated is selectively applied to the anode, and when the plating is interrupted, a second applied current having a smaller current amount than the first applied current is applied to the anode. A power supply to selectively apply;
Equipped with plating equipment.   5. The auxiliary anode according to claim 4, further comprising an auxiliary anode installed in the auxiliary plating tank and connected to the power source so as to correspond to the transfer means as the cathode that passes through the auxiliary plating tank. Plating equipment.   The plating apparatus according to claim 5, wherein the auxiliary anode is connected to the power source by being connected to the anode connected to the power source.   5. The plating equipment according to claim 4, wherein the anode extends into the auxiliary plating tank corresponding to the transfer means as a cathode passing through the auxiliary plating tank.   The plating equipment according to claim 4, further comprising a sensor installed in the auxiliary plating tank in order to sense the plating solution flowing into the auxiliary plating tank.   The power source applies the second applied current at a current amount of 5% to 40% of the first applied current when the first applied current is switched to the second applied current. The plating equipment as described in 4. A series of a plurality of main plating tanks in which a plating solution is placed, an anode immersed in the plating solution in the main plating vessel, an auxiliary plating vessel in which the main plating vessel is connected and the plating solution flows, and the anode In a plating method using a plating equipment comprising a corresponding cathode, a transfer means for sequentially transferring products to be plated to the main plating tank and the auxiliary plating tank, and a power source for applying a current to the anode,
Continuously supplying the products to be plated by the transfer means and passing the products to be plated through the main plating tank and the auxiliary plating tank;
Applying a first applied current for plating on the product to be plated from the power source to the anode to advance the plating on the product to be plated;
When the plating is interrupted, by applying a second applied current having a current amount smaller than the first applied current from the power source to the anode, a plating failure of the product to be plated is generated during the interruption of the plating. The stage of preventing
After the interruption of plating is eliminated, the second applied current is converted to the first applied current by the power source to continue plating the product to be plated;
The plating method characterized by including.   The plating method according to claim 10, wherein the plating solution contains tin and bismuth, and a tin: bismuth plating layer is formed on the product to be plated by the plating.   The plating method according to claim 10, wherein the second applied current has a current amount of 5% to 40% compared to the first applied current. The plating equipment further includes an auxiliary anode installed in the auxiliary plating tank,
The plating method according to claim 10, wherein the second applied current is applied from the power source to the auxiliary anode and the anode. The plating equipment further includes an auxiliary anode installed in the auxiliary plating tank,
The plating method according to claim 13, wherein the first applied current is applied from the power source to the auxiliary anode and the anode. Immersing at least one product to be plated in at least one plating bath containing a plating solution;
Applying a current for plating the product to be plated to at least one anode immersed in the plating solution;
Reducing the plating current applied to the anode when the plating is interrupted;
After the interruption of the plating is resolved, the plating current is converted to the previous amount to continue the plating on the product to be plated;
The plating method characterized by including.   The plating method according to claim 15, wherein the plating current is reduced from 5% to 40% of the original value.   The plating method according to claim 15, wherein the plating solution contains tin and bismuth, and a tin: bismuth plating layer is formed on the product to be plated by the plating. A series of main plating baths into which the plating solution is placed;
An anode immersed in the plating solution of the main plating tank;
An auxiliary plating tank that connects between the main plating tanks and the plating solution flows;
A cathode corresponding to the anode, a transfer means for sequentially transferring products to be plated to the main plating tank and the auxiliary plating tank;
Applying a current for plating to the product to be plated to the anode and reducing the current when the plating is interrupted;
Equipped with plating equipment. At least one plating tank containing a plating solution for plating at least one product to be plated;
A power source that applies a first applied current to the plating solution for plating on the product to be plated and selectively applies a second applied current having a smaller current amount than the first applied current when the plating is interrupted. When,
Equipped with plating equipment. Plating at least one product to be plated that passes through at least one plating bath containing a plating solution for plating;
Reducing the first current for the plating and converting it to a second current while the plating is interrupted;
The plating method characterized by including.   21. The plating method according to claim 20, wherein the second current is low enough not to cause the plating and high enough not to cause substitution or deposition of the components of the plating solution. At least one main plating tank;
In order to prevent at least one product to be plated from being exposed to the environment outside the plating solution, at least one auxiliary connected to the main plating bath so that the plating solution flows from any one of the main plating baths. A plating tank,
Equipped with plating equipment.

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