JPH05235232A - Electronic component, method and apparatus for surface treating electrode terminal thereof and surface treating solution - Google Patents

Abstract

PURPOSE:To mount at a fine pitch by dipping an electrode terminal in solder or tin electrolyte in which rosin flux adsorbed with anionic surfactant is dispersed, and separating out the flux adsorbed with the surfactant together with solder or tin on its surface. CONSTITUTION:When flux particles made of rosin flux are dispersed in anionic surfactant, anionic surfactant particles are adsorbed to its periphery to store '+' charge in the flux particles themselves. The flux particles are added to and dispersed in plating solution in which solder is dissolved in electrolyte and Sn2<+>, Pb2<+> ions exist. In a plating apparatus 5, when a hoop material 3 to become an electrode terminal and a solder electrode conveyed into the solution are dipped and electrolytically plated, the solder and the flux particles are simultaneously separated out on the surface of the material 3. Thus, the generation of a solder ball and short-circuit between electrodes are prevented, and electronic components can be mounted at a fine pitch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method, a surface treatment apparatus, and a surface treatment solution for electronic components such as LSI chips, which are mounted on a substrate by soldering, and electrode terminals thereof.

[0002]

2. Description of the Related Art To mount an electronic component such as an LSI chip on a printed circuit board by soldering, a flux (generally a rosin-based flux) which plays a role of cleaning and improving wettability of a metal surface to be soldered, and solder And are required. For example, as shown in FIG. 7, cream solder 8 (formed into a cream form by mixing solder particles and flux) is printed on the terminal surface 7 of the printed circuit board, and the electrode terminal 2 of the electronic component 1 is printed thereon.
Was placed and heated in a reflow furnace.

FIG. 8 shows this electronic component mounter. That is,
The surface 7 of the terminal of the printed circuit board with the cream solder printer 10
The cream solder 8 is printed on the printed circuit board, the electronic component 1 is placed on the printed circuit board by the chip mounter 11, and the cream solder 8 is heated and melted in the reflow furnace 12 to be soldered and mounted.

In this case, the electrode terminals of the electronic component are soldered or tin-plated (3-5 μm) in order to improve solder wettability.
m) is applied. Since this plating is only for improving the wettability, it is not plated with a thickness of 5 μm or more.

[0005]

However, with the recent miniaturization of electronic equipment, miniaturization of electronic parts is also rapidly progressing. When electronic components are miniaturized, the electrode terminal pitch of a printed circuit board on which these electronic components are mounted also becomes finer, so that soldering to a fine pattern is required. However, as shown in FIG. 7, the soldering of the fine pattern has a problem that the yield of the soldering process is reduced due to the generation of the solder balls 9 and the short circuit between the electrodes due to the solder.

An object of the present invention is to prevent the generation of solder balls and a short circuit between electrodes to enable mounting of electronic components on a fine pitch, and to reduce the solder paste printing process, and the surface of the electrode terminals thereof. To provide a treatment method, a surface treatment device, and a surface treatment liquid.

[0007]

A first aspect of the present invention is a surface treatment method for an electrode terminal in an electronic component, which is in a solder or tin electrolyte solution in which a rosin flux having an anionic surfactant adsorbed therein is dispersed. And a step of precipitating a rosin-based flux having an anionic surfactant adsorbed together with the solder or tin on the surface of the electrode terminal. A second aspect of the present invention is a surface treatment apparatus for electrode terminals in an electronic component, which is a rosin-based surface treatment method for an electrode terminal of an electronic component, in which an anionic surfactant is adsorbed. First means for immersing an electrode terminal of an electronic component in a solder or tin electrolyte solution in which flux is dispersed, and a rosin-based flux in which an anionic surfactant is adsorbed on the surface of the electrode terminal together with the solder or tin. And a second means for precipitating. ◇ A third invention is an electronic component, wherein the electrode terminal of this electronic component and the electrode terminal are immersed in a solder or tin electrolyte solution in which a rosin flux having an anionic surfactant adsorbed is dispersed. As a result, the surface of the electrode terminal has a rosin-based flux having an anionic surfactant adsorbed together with the solder or tin adsorbed thereon. ◇ A fourth invention is a surface treatment liquid for an electrode terminal in an electronic component, which comprises an anionic surfactant, a rosin flux adsorbing the anionic surfactant, and the rosin flux dispersed therein. A rosin-based flux having a solder or tin electrolytic solution and adsorbing an anionic surfactant together with the solder or tin is deposited on the surface of the material to be treated.

[0008]

According to the present invention, the rosin-based flux having the anionic surfactant adsorbed together with the solder or tin is deposited on the surface of the electrode terminal by having the above-described means, and the above-mentioned electrode is mounted on the substrate when mounted on the substrate. Solder deposited on the terminal surface or rosin-based flux that adsorbs tin and anionic surfactants can be soldered without causing solder balls or short-circuiting between electrodes even when mounted on a fine pitch. It is possible to obtain electronic components that can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing an external configuration of the LSI chip 1. The LSI chip 1 has a plurality of electrode terminals 2. The electrode terminal 2 is formed by pressing a hoop material.

FIG. 2 is a flow chart for explaining the steps from the hoop material which is the material of the electrode terminals to the formation of the electrode terminals 2 of the LSI chip 1. The hoop material is first punched into a shape of an electrode terminal by a pressing process to form an electrode terminal. FIG. 3 is a plan view showing the hoop material 3 after press working. The hoop material 3 is formed with a plurality of strip-shaped portions 3a to be electrode terminals by pressing. When the pressing process is completed, the hoop material 3 proceeds to the plating process.

FIG. 4 is a diagram showing details of the plating process.
The hoop material 3 after pressing is wound around the reel 4. The hoop material 3 delivered from the reel 4 is conveyed to the plating device 5. In the plating device 5, after performing a pretreatment step of removing dirt such as press oil adhering to the hoop material 3,
Proceed to the plating process (electrolytic plating). A plating solution in which flux particles are dispersed is used in the plating process.

FIG. 5 is a view showing the concept of dispersing flux particles in a plating solution. Here, the rosin-based flux is obtained by dissolving rosin (containing 80 to 90% by weight of abietic acid) as a main component in a solvent such as IPA (isopropyl alcohol) in an amount of 20 to 50% by weight / volume%. The flux particles of the rosin-based flux are fine particles having a diameter of 3 μm or less. When the flux particles are dispersed in the anionic surfactant, the anionic surfactant particles are adsorbed around the flux particles, and the flux particles themselves are charged with “+”. Then, solder particles (alloy of tin and lead) are dissolved in an electrolytic solution, and flux particles in which anionic surfactant particles are adsorbed are added at a ratio of 10 to 15% by weight to a plating solution containing Sn2 + and Pb2 + ions. And disperse.

Returning to FIG. 4, in the plating step, electrolytic plating is performed using the above-mentioned plating solution. That is, the hoop material 3 to be an electrode terminal and the solder electrode (plate-shaped solder) are immersed in the plating solution. Next, the hoop material 3 is used as the "-" electrode and the solder plate is used as the "+" electrode to pass a current. in this case,
The plating thickness depends on the amount of current and time. In this embodiment, the plating thickness is thicker than the normal plating thickness (3 to 5 μm), and solder is deposited on the surface of the hoop material 3 to a plating thickness of 10 to 20 μm. At this time, since the flux particles in which the anionic surfactant particles are adsorbed are dispersed in the plating liquid, both the solder and the flux particles are deposited (eutectoid) on the surface of the hoop material 3.

When the plating process is completed, the cleaning process proceeds to wash the hoop material 3, and the drying process proceeds to dry. Then, the hoop material 3 that has exited the plating apparatus 5 is wound on the winding reel 6.

Returning to FIG. 2, when the plating process is completed,
Next, the bonding process is performed. In this bonding step, the LSI chip is placed on the hoop material 3 plated with solder and flux particles, and the strip-shaped portion 3a of the hoop material 3 to be the electrode terminal 2 is bonded to the LSI chip. When this bonding process is completed, the process proceeds to the molding process. In the molding process, the bonded LSI chip portion is molded with resin. When the molding process is completed, unnecessary portions of the hoop material 3 are cut to separate the plurality of electrode terminals 2 (strip portions 3a) from each other, and the LSI chip 1 having the shape shown in FIG. 1 is completed.

Since the flux is deposited together with the solder on the surface of the electrode terminal 2 in the LSI chip 1 by the steps described above, a small amount of the solder and the flux can be uniformly supplied unlike the cream solder, and the cream solder is used. No need. That is, as shown in FIG. 6, the electrode terminals 2 of the LSI chip 1 are positioned on the terminal surface 7 of the printed circuit board by the chip mounter 11 shown in FIG. The solder and the solder are heat-melted in this order, and the electrode terminal 2 is soldered to the terminal surface 3 of the printed board.

[0017]

According to the present invention, a rosin flux having an anionic surfactant adsorbed together with solder or tin is deposited on the surface of an electrode terminal and deposited on the surface of the electrode terminal when mounted on a substrate. It is possible to obtain an electronic component that can be soldered to a substrate with solder or a rosin-based flux that adsorbs tin and an anionic surfactant, and prevent generation of solder balls and short-circuiting between electrodes to achieve a fine pitch. It is possible to provide the electronic component capable of mounting the electronic component and reducing the solder paste printing process, the surface treatment method of the electrode terminal thereof, the surface treatment apparatus, and the surface treatment liquid.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external configuration of an LSI chip.

FIG. 2 is a flowchart showing an operation until a hoop material is processed into an LSI electrode.

FIG. 3 is a diagram showing a hoop material after pressing.

FIG. 4 is a diagram showing a plating process of a hoop material.

FIG. 5 is a conceptual diagram showing a state in which flux particles are dispersed in a plating solution.

FIG. 6 is a diagram showing a mounting structure that does not use cream solder.

FIG. 7 is a diagram showing a conventional mounting state using cream solder.

FIG. 8 is a diagram showing a series of devices from a cream solder printing machine to a reflow oven.

[Explanation of symbols]

 1 ... LSI chip 2 ... Electrode terminal 3 ... Hoop material 4 ... Reel 5 ... Plating device 6 ... Take-up reel 7 ... Terminal surface 8 ... Cream solder 9 ... Solder ball 10 ... Cream solder printer 11 ... Chip mounter 12 ... Reflow oven

Claims (4)

[Claims] 1. A step of immersing an electrode terminal of an electronic component in a solder or tin electrolyte solution in which a rosin-based flux having an anionic surfactant adsorbed therein is dispersed; And a step of depositing a rosin-based flux having an anionic surfactant adsorbed thereon, the surface treatment method of an electrode terminal in an electronic component. 2. A method for treating the surface of an electrode terminal of an electronic component, the method comprising the step of treating an electrode terminal of an electronic component with a solder or tin electrolyte in which a rosin flux having an anionic surfactant adsorbed therein is dispersed. And a second means for precipitating a rosin flux having an anionic surfactant adsorbed together with the solder or tin on the surface of the electrode terminal. Electrode terminal surface treatment device for electronic parts. 3. An electrode terminal and the solder or tin on the surface of the electrode terminal by immersing the electrode terminal in a solder or tin electrolyte solution in which a rosin flux in which an anionic surfactant is adsorbed is dispersed. An electronic component, comprising: a rosin-based flux having an anionic surfactant adsorbed together with the rosin-based flux. 4. An anionic surfactant, a rosin flux having the anionic surfactant adsorbed thereon, and a solder or tin electrolyte solution in which the rosin flux is dispersed. A surface treatment liquid, characterized in that a rosin flux having an anionic surfactant adsorbed is deposited together with the solder or tin.