JPH0229737Y2 - - Google Patents

Description

[Detailed description of the invention] - Industrial application field The present invention relates to a ceramic hook made of various ceramic sintered bodies used for soldering work of printed wiring boards.

・ Conventional technology In general, soldering work for printed wiring boards is carried out by suspending printed wiring boards from a conveyor cable such as a chain driven in a bath containing hot molten solder (hereinafter referred to as a solder dip tank for convenience). dipped while continuously inserting the
This is the process of attaching solder to the required circuit parts of the board, such as land parts and through-hole parts. Therefore, as shown in the plan view of Figure 1, an automatic soldering device used for soldering printed wiring boards consists of, for example, a flux board for flux treatment, a preheater for preheating the board, and a molten solder. An apparatus is used which consists of a solder dip tank (c) for immersing the board in a liquid, and a cooler (d) for rapidly cooling the board etc. after soldering. In each device in each of these series of steps, a substrate holding finger (hereinafter also simply referred to as a finger) is locked to a conveyance chain, and the substrate is automatically moved in the direction of the arrow with the substrate held by the finger. transported. In this way, the equipment at each step of the solder flow,
The substrates will be processed in steps (b), (c), and (d), respectively.

・Problems to be solved by the invention However, since conventional fingers for holding printed wiring boards are coated with stainless steel Teflon, the fingers are corroded by flux gas derived from various organic solvents in the flux and chemicals such as hydrochloric acid. The fingers may be heated in hot molten solder, causing distortion and warping, or the molten solder may adhere to a part of the finger surface, or the conveyor chain may come into rotating contact with the tension sprocket or drive roller, causing friction. There were drawbacks such as the finger locking part gradually becoming worn out each time it was used.

・Means and effects for solving the problems In order to eliminate and improve the above-mentioned drawbacks of the conventional fingers, this invention has excellent properties such as thermal shock resistance, abrasion resistance, and corrosion resistance, is lightweight, and uses molten solder. Fingers of various shapes are constructed from ceramic sintered bodies that have the characteristic that no particles adhere to them at all.

The ceramic hook of the present invention will be specifically described below based on examples and drawings.

FIG. 2 is a longitudinal sectional view of the ceramic hook of the present invention. In this drawing, reference numeral 1 indicates a finger body, and more specifically, a finger body for gripping a printed wiring board used for soldering work. In addition, the printed wiring board as used in the present invention refers to various substrates such as ceramic substrates, glass epoxy substrates, phenol paper substrates, and polyamide flexible substrates on which conductor circuits are formed, or on which components such as semiconductors or resistors are mounted. It is installed. The finger body is composed of various ceramic sintered bodies of carbides, nitrides, and oxides such as silicon carbide, boron carbide, silicon nitride, boron nitride, alumina, zirconia, forsterite, and steatite. Ceramic materials generally have superior thermal shock resistance, abrasion resistance, and corrosion resistance compared to metal materials, and furthermore, they are lightweight and do not attract molten solder. Therefore, compared to conventional metal composite fingers, there is less deformation even when heated, there is almost no wear due to friction, and there is no corrosion due to flux gas. Furthermore, since molten solder does not adhere to the surface at all, there is no need to remove solder residue from the fingers.

2 is a recess provided at one end of the finger body for holding the printed wiring board horizontally;
As shown in FIG. 4, this recess has various shapes such as V-shape A, key-shape B, semicircular C, E, and U-shape D. This recess is a portion for holding the printed wiring board horizontally.

3 is a mounting hole provided at the other end of the finger for engaging a cable such as a board conveyance chain. The positions of these holes correspond to the fixing holes provided in the board transfer chain, and the upper end of the finger can be freely fixed in any position using fixing tools such as screws, nuts, and bolts. It is something. Note that the shape of the hole is not particularly limited.

FIG. 3 is a front view of the ceramic hook of the present invention, and 1 to 3 are the finger body 1, the recess 2, and the mounting hole 3, as shown in the previous figure. 4 is a notch at the tip of the finger, which reduces the resistance of the solder liquid when immersed in a molten solder bath, improves the drainage of the solder liquid when the board etc. is lifted from the liquid, and also eliminates the need for extra material. It also has the effect of reducing the weight of the main body. Reference numeral 5 denotes a notch on the side of the figure main body, which provides the same effect as the notch at the tip.

FIG. 4 is a side view showing various shapes of recesses at the tip of the finger. 1 is a main body, and 2 is a recessed portion.

FIG. 5 is a perspective view of the ceramic hook of the present invention attached to the board conveying cable. Reference numeral 1 designates the finger body, 3 a mounting hole, 4 a cutout at the tip, 6 a board conveyance cable, and 7 a printed wiring board.

・Example 5 A finger shaped as shown in FIGS. 2 and 3 is constructed of a ceramic material containing silicon carbide as a main component, and semiconductors and other electronic components are mounted and mounted on a printed wiring board. When the product was suspended as shown in the figure and transported and inserted into a solder dip tank for solder reflow, which was heated and melted at approximately 350°C, a number of excellent effects were confirmed as shown below.

- Effects of the invention (1) Approximately half the weight of conventional metal fingers
The weight can be reduced to one-third from the previous one.

Further weight reduction can be achieved by providing a notch at the tip or side surface of the finger body as illustrated in FIGS. 2 and 3.

(2) Due to its excellent wear resistance, there is almost no wear loss like with conventional metal fingers.

(3) Even after repeated use, no deformation such as distortion or warping occurred due to heating and cooling recycling.

(4) Since the printed wiring board is fitted in the recess and an appropriate tension can be applied to the board, the warpage of the board is less than before.

(5) Corrosion resistance has been improved as there is no corrosion caused by gases derived from various chemicals generated from flux.

(6) If the material of the finger body is carbide-based ceramics such as silicon carbide sintered body or boron carbide sintered body, it has no particular affinity with solder, and solder may adhere to the surface of the finger tip. It's convenient because there's nothing to do.

Therefore, the following secondary effects also occur.

(7) When removing the printed wiring board, since there is no solder attached to the hook, the board can be removed easily and quickly.

As described above, according to the present invention, the finger body is made of various ceramic materials, so it has better corrosion resistance, abrasion resistance, thermal shock resistance, etc. than metal, and there is no solder adhesion, making it lightweight and inexpensive. It is possible to provide a hook for transporting a printed wiring board.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an example of a solder bath for a printed wiring board, Fig. 2 is a side sectional view of a ceramic hook of the present invention, Fig. 3 is a front view of a ceramic hook of the present invention, and Fig. 4 is a finger FIG. 5 is an explanatory diagram showing various shapes A to H of the recesses for holding a board at the tip of the main body, and FIG. 5 is a perspective view of a state in which a hook is hung from a board conveyance cable to support a board. 1...Finger body, 2...Concavity at the tip, 3
...Mounting hole at the other end, 4...Notch at the tip, 5...
Notch on the side.

Claims (1)

[Claims for Utility Model Registration] 1. A finger for holding a printed wiring board used for soldering work of a printed wiring board, which has a concave portion at the tip of the main body 1 for holding the board, and other than the main body 1 of the finger. A ceramic hook made of a ceramic sintered body having a mounting hole 3 at its end for engaging a board carrying cable, wherein the board holding finger of the hook has a notch 4 at its tip, and A ceramic hook characterized in that the tip of the finger has a structure in which it makes linear contact with the substrate and grips it. 2. A utility model characterized in that the ceramic sintered body is one of silicon carbide, boron carbide, boron nitride, alumina, zirconia, etc., and is a ceramic material particularly excellent in heat resistance, wear resistance, and corrosion resistance. A hook according to claim 1 of the registered claim.