KR100326300B1 - Solder ball and method for coating it - Google Patents

Abstract

The present invention relates to a solder ball for a ball grid array (BGA) package and a plating method thereof. Conventionally, solder balls are oxidized and corroded by air contact during the package manufacturing process, as well as discoloration and deformation due to friction and impact caused by contact between solder balls, resulting in defects and difficulties in package manufacturing and electrical contact resistance. There was a problem that caused a malfunction.

Therefore, in the present invention, the opening portion 21 having the latching jaw 22 is formed at both sides in the plating bath 10 in which the plating solution 10A is contained, and the drum 20 is installed in the transverse direction so as to be rotatable with the rotation shaft 23. A sphere 100 made of an alloy of lead and tin is introduced into the drum, and a positive electrode connected to the negative electrode 31 and the plating solution 10A of the power supply unit 30 formed in a coil spring form in the drum 20. A method of plating a solder ball by applying power to an electrode 32 is provided, and a single coating film 100A of tin 111 is formed on the surface of a sphere 100 serving as a base material of the solder ball, or Copper 120 and solder 121 and tin 122 or silver 131 and solder 132 and tin 133 and silver 141 and copper 142 and solder 143 and tin 144 Since the solder balls formed with the multilayered coating layers 120, 130, and 140 of the multi-layer coating layer are provided, the shape is discolored and deformed due to friction and impact due to contact between the solder balls during the manufacturing process. In addition, it is possible to prevent oxidation and corrosion due to contact with external air, and to significantly reduce the defect rate of semiconductor package manufacturing. In addition, since the plating of the solder ball having a fine diameter of 0.55 mm or less is made more uniform, the quality of the product can be improved.

Description

Solder Ball and Plating Method {SOLDER BALL AND METHOD FOR COATING IT}

The present invention relates to a solder ball for a ball grid array (BGA) package and a plating method thereof, and in particular, to prevent deformation and discoloration and corrosion of the solder ball due to friction and impact caused by contact between solder balls during a BGA package manufacturing process. It relates to a solder ball and a plating method thereof so as to prevent it.

Recently, due to the development of hybrid integrated circuit (HIC) design and assembly technology, high functionalization has been achieved, and HIC's packages are also divided into SIP (Single In-line Package), DIP (Dual In-line Package) and QFP (Quad Flat Package). The input and output terminals have been increased to 100 mils (1 mil; 1/1000 inch), 75 mils, and 50 mils.

In addition, there are hundreds of input / output terminals and a surface mountable device is required. Therefore, a lead-free ball grid array (BGA) semiconductor package has recently been developed as an HIC package.

The BGA package is divided into gold (Au), silver BGA, and solder BGA depending on the type of ball, but the BGA package in the form of a solder ball having strength in terms of price is widely applied to HIC. It is made of an alloy of tin and lead having a% content, and is formed on the lower surface of a printed circuit board (PCB) to connect a circuit inside the package with a circuit outside the package.

More specifically, as shown in FIG. 4, the BGA semiconductor package attaches a semiconductor chip 102 on which a desired circuit element is formed by a wafer processor directly on a printed circuit board (PCB) 101. In addition, the chip pad of the semiconductor chip 102 is electrically connected to the circuit pattern on the printed circuit board 101 by wire 103 to protect the semiconductor chip 102 and the wire 103 from an external environment. In order to form the epoxy molding compound 104. In addition, the solder ball (S) is fused to the bottom surface of the printed circuit board 101 for the signal extraction of the semiconductor chip 102, the solder ball (S) and the semiconductor chip 102 is inside the printed circuit board 101 It is electrically connected by a predetermined conductive pattern formed so that an external electrical signal enters the semiconductor chip 102 so that data from the semiconductor chip 102 can be output to the outside through the solder ball S. In particular, the solder ball S is used as a power voltage terminal or a ground power terminal, and since the connection distance is short, the inductance and resistance can be reduced, and the heat generated from the semiconductor chip 102 can also be discharged to the outside. do. After the solder ball S is fused to the bottom surface of the printed circuit board 101, the ball grid array semiconductor package is configured by connecting the solder ball S to the motherboard (main printed circuit board).

However, such a conventional solder ball is not only oxidized or corroded by contact with external air during the package manufacturing process, but also causes a lot of defects due to discoloration and deformation due to friction and impact caused by contact between solder balls. There was a problem that caused a malfunction due to signal input and output by contact.

Therefore, the present invention was devised to solve the conventional problems as described above, the object of which is the discoloration and deformation of the shape due to friction and impact due to contact between the solder balls during the manufacturing process, or oxidized by contact with external air To prevent corrosion or corrosion. Another object of the present invention is to make the plating of the solder ball more uniform.

In order to achieve the object of the present invention, the electroplating apparatus of the electroplating apparatus is formed in the coil spring form in the inner side of the drum is formed in both sides of the opening having a locking jaw in the plating bath containing the plating solution and installed in the transverse direction so as to rotate about the rotation axis. Inside the drum, a large number of spheres made of an alloy of lead and tin are introduced and embedded, and the electric current is rotated while the drum 20 is rotated while introducing a negative charge to the power supply and immersing an electrode having a positive charge in the plating solution. Provided is a plating method of a solder ball, characterized in that to supply.

And there is provided a solder ball, characterized in that the coating film of tin (100A) is formed on the surface of the sphere 100 of the alloy of lead and tin.

Further, a primary copper layer 121 is formed on the surface of the sphere 100 made of an alloy of lead and tin, and a solder layer 122 made of an alloy of 27% lead and 63% tin is formed thereon. There is provided a solder ball, characterized in that the tin layer 123 is formed on the solder layer 122.

Further, a primary silver layer 131 is formed on the surface of the sphere 100 made of an alloy of lead and tin, and a solder layer 132 made of an alloy of 27% lead and 63% tin is formed thereon. A solder ball is provided, characterized in that a tin layer 133 is formed on the layer 132. A primary silver layer 141 is formed on the surface of the sphere 100 made of an alloy of lead and tin, and copper is formed thereon. A layer 142 is formed, and a solder layer 143 formed of an alloy of 27% lead and 63% tin is formed on the copper layer 142, and a tin layer 144 is formed on the solder layer 143. Featured solder balls are provided.

1 is a block diagram of a plating apparatus showing an embodiment of the present invention.

2 is a block diagram of a plating apparatus showing another embodiment of the present invention.

Figure 3a, Figure 3b, Figure 3c, Figure 3d is a cross-sectional view showing a solder ball structure of the present invention.

Figure 4 is a cross-sectional view showing the internal structure of a typical BGA semiconductor package.

* Explanation of symbols on the main parts of the drawings *

S: Solder Ball

1,10: Plating tank

1A, 10A: Plating solution

2: working sleeve

3,30: power supply

3A, 31: (-) electrode 3B, 32: (+) electrode

20: drum

21: Opening part 22: Jam jaw

23: rotating shaft

100: Old

101A, 120, 130, 140: Coating film 111, 123, 133, 144: Tin

121,142: Copper 122,132,143: Solder

131,141: Silver

Hereinafter, the solder ball plating method of the present invention will be described in detail with reference to the accompanying drawings.

The plating method of the solder ball according to the present invention is largely divided into a wet method and a dry method, and the wet method is further classified into an electroplating method and a chemical method, and a representative method of the dry method is a vacuum deposition method.

First embodiment

This is an electroplating method, as shown in Figure 1, injecting a plurality of spheres 100 as the base material of the solder ball to the operating medium (2) installed in the state locked in the plating solution (1A) of the plating bath (1). Thereafter, the (-) electrode 3A is connected to the working chamber 2 and the (+) electrode 3B operates the power supply unit 3 connected to the plating solution 1A of the plating bath 1 to operate the (-) electrode. Power is applied to the electrode 3A and the positive electrode 3B, respectively. Then, when the operating member 2 is oscillated by mechanical operation, the sphere 100 and the plating liquid 1A injected into the operating cylinder 2 react with each other, as shown in FIG. 3A on the surface of the sphere 100. As described above, the coating film 100A is formed, wherein the plating solution 1A is pure tin having a content of 63% to 100% (actually 99.9%).

On the other hand, if the plating process is sequentially performed by varying the components of the plating solution 1A with a plurality of devices as described above, as shown in FIGS. 3B, 3C, and 3D, a coated solder ball made of a multilayer film is produced. . That is, when a plating process is sequentially performed with a plurality of devices in which the component of the plating liquid 1A is copper and a device in which the component of the plating liquid 1A is silver, solder, and copper are sequentially formed, as shown in FIGS. 3B to 3D. Solder balls (S) having a multi-layer coating film (120, 130, 140) is formed.

FIG. 3B shows a copper layer 121 formed on a surface of a sphere 100 made of a 27% lead and 63% tin alloy, and a solder layer 122 containing 63% or more of tin is formed thereon. A pure tin layer 123 having a content of 63% or more is formed on the 122 to form a coating film 120.

In addition, Figure 3c forms a silver layer 131 of silver on the surface of the sphere 100 made of a 27% lead and 63% tin alloy, and forms a solder layer 132 containing 63% or more of tin thereon, again. A pure tin layer 133 having a content of 63% or more is formed on the solder layer 132 to form a coating film 130.

3D shows a silver layer 141 made of silver on a surface of a sphere 100 made of a 27% lead and 63% tin alloy, a copper layer 142 formed thereon, and a tin layer formed on the copper layer 142. The solder layer 143 and the pure tin layer 144 containing 63% or more are sequentially formed to form the coating layer 140.

Here, the copper and silver layers have reinforcement along with their excellent conductivity, and the solder layer improves adhesion by fusion during the package manufacturing process, so that the work can be made more easily, and the tin layer is oxidized by external air contact. And preventing discoloration due to corrosion and friction between the solder balls.

Second embodiment

In addition, as the electroplating method as in the first embodiment, first, the apparatus as shown in FIG. 2 is provided, which is open at both sides to the plating bath 10 in which the plating liquid 10A is contained, and the opening 21 The cylindrical drum 20 in which the locking step 22 is formed to protrude inwardly is installed in a state in which a part of the cylindrical drum 20 is immersed in the plating liquid 1A. In addition, the rotating shaft 23 is installed on both sides of the drum 20 is configured to rotate the drum 20 by the driving force of the drive motor (not shown). In addition, a power supply unit 30 is formed outside the drum 20, and a negative electrode 31 of the power supply unit 30 is formed in a coil spring or a mesh form inside the drum 20, and a power supply unit 30 is formed. The positive electrode 32 of) is connected to the plating liquid 1A in the plating bath 1.

In this plating apparatus, the present invention first, a plurality of solder balls, that is, spheres 100 made of an alloy having a content of 27% lead and 63% tin in the drum 20 is introduced. Then, the power supply 30 is operated to drive the drum 20 while applying power to the negative electrode 31 of the drum 20 and the positive electrode 32 of the plating solution 10A. When rotated with a driving force of the), the sphere 100 and the plating liquid 1A having a diameter of 0.5 mm or less, that is, a fine diameter of 0.35 mm in the drum 20 react with each other to reach the surface of the sphere 100. As shown in 3a, a coating film 100A is formed, wherein the coating film 100A is made of pure tin 111 having a content of 63% or more.

In addition, as in the first embodiment, when a plurality of devices are provided for each plating solution to perform a sequential plating process, a solder ball having multiple coating layers 120, 130, and 140 as illustrated in FIGS. 3B to 3D is performed. (S) is produced.

Third embodiment

This is a vacuum deposition method, in which a sphere 100, which is the base material of the solder ball S, is accommodated in a vacuum chamber into which a reaction gas is injected, and a plating material of tin or copper and silver having a content of 63% or more is provided on the lower side thereof. 3A to 3D by selectively accommodating and mutually reacting by applying power of the (+) electrode and the (-) electrode by operation of a power supply unit having a sphere as a (-) electrode and a plating material as a (+) electrode. As shown, the coating film 100A, 120, 130, 140 is formed on the surface of the sphere 100.

Fourth embodiment

This is a chemical ion exchange method in which when a material causes friction with a counterpart having a high ionization tendency, the friction causes the plating of the counterpart having a high ionization tendency to transfer to the surface of the material. Some materials are the bases of solder balls, and the counterparts are white powder tin or copper and silver plating materials that tend to ionize more than lead.

As described above, the present invention allows a single layer film of tin or a multi-layer coating film made of copper, silver, solder, etc. to be formed on the base surface of the solder ball, thereby maintaining the characteristics of copper and silver itself having excellent conductivity, and solder ball during the package manufacturing process. The friction and impact caused by contact between each other can prevent the form from being discolored and deformed, as well as the oxidation and corrosion caused by air contact. In addition, this has the effect of reducing the defect rate of semiconductor package manufacturing and further increasing the simplicity and efficiency of the operation. And since the plating of the solder ball having a fine diameter of 0.5mm or less is made more uniform, there is an effect that can improve the quality of the product.

Claims (7)

In the plating tank 10 in which the plating liquid 10A is contained, an opening portion 21 having a locking jaw 22 is formed at both sides, and the drum 20 is installed in the transverse direction so as to be rotatable about the rotation shaft 23. A plurality of spheres 100 made of an alloy of lead and tin are introduced into the drum 20 of the electroplating apparatus in which the power supply unit 30 is formed in the form of a coil spring, and a negative charge is introduced into the power supply unit 30. And supplying a current while rotating the drum (20) while immersing the electrode (32) having a positive charge in the plating solution (10A). delete delete The solder ball, characterized in that the coating film of tin (100A) is formed on the surface of the sphere 100 of the alloy of lead and tin by the method of claim 1. The primary copper layer 121 is formed on the surface of the sphere 100 made of an alloy of lead and tin by the method of claim 1, and the solder layer 122 made of an alloy of 27% lead and 63% tin is formed thereon. Is formed, the solder ball, characterized in that the tin layer 123 is formed on the solder layer 122. The primary silver layer 131 is formed on the surface of the sphere 100 made of an alloy of lead and tin by the method of claim 1, and a solder layer 132 made of an alloy of 27% lead and 63% tin is formed thereon. And, the solder ball, characterized in that the tin layer 133 is formed on the solder layer 132. The primary silver layer 141 is formed on the surface of the sphere 100 of the alloy of lead and tin by the method of claim 1, a copper layer 142 is formed thereon, and a lead 27 on the copper layer 142. Solder ball characterized in that the solder layer 143 is formed of an alloy of% and 63% tin, the tin layer 144 is formed on the solder layer 143.