JPS6188964A - Production of shielding chassis - Google Patents

Abstract

PURPOSE:To prevent the clogging of the holes of a chassis for a high frequency circuit product with solder and the generation of droppings in the stage of dipping the chassis into the solder after coating of a flux thereon to fill the fitting holes with the solder and to manufacture said chassis by passing the chassis into the floating film of the flux and taking out the same. CONSTITUTION:The surface of the manufactured chassis is cleaned by degreasing and thereafter the entire part of the chassis is dipped into a flux tank. The chassis is thereafter taken out of the flux tank and the entire part of the chassis is warmed. Such chassis 5 is then dipped into a solder melting tank 1. The solder in the tank 1 is held at about 250 deg.C and an oxide film is removed (the jet is held temporarily stopped in the jet solder melting tank) and thereafter the above-mentioned dipping is carried out at within about 5sec. Then the flux coated on the chassis 5 is stripped from the chassis 5 and floats on the solder surface 2, thus forming the flux floating film 6. While the chassis 5 is passed through the inside of the film 6 in the state of preventing the dispersion of the film 6, the chassis is risen at about 10mm/sec speed and is taken out. The chassis is dipped in about 2-5% soln. of water and dilute hydrochloric acid, by which the chassis is washed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a manufacturing method for manufacturing a shielded chassis used for high frequency circuit products such as converters and tuners, and more specifically relates to a manufacturing method for manufacturing a shielded chassis used for high frequency circuit products such as converters and tuners. The present invention relates to a manufacturing method for manufacturing a shield chassis by filling gaps such as a fitting part with a plate with solder.

[Background of the invention]

For example, in devices that handle very high frequency signals, such as TV converters, KEI
(If a gap exists, radio waves may be exchanged between the boards placed in each partition through the gap, which may impair the electrical characteristics. In general, the gap is filled with solder and electromagnetically shielded to prevent the exchange of radio waves.

Therefore, in order to fill the gaps between each fitting part with solder, the conventional method is to place thread solder on the fitting part (corner part) Ic between the chassis frame and the partition plate, and pass it through a melting furnace as it is. As a result, I had to melt the solder to fill in the gaps. but,
Generally, a chassis has about 40 mating parts, so in reality, it is necessary to repeat the above process several times while changing the orientation by turning the entire chassis sideways or upside down. However, the drawback was that it took a lot of man-hours.

Therefore, the entire chassis was immersed directly into the solder melting tank.
One possible method is to fill in the gaps between each fitting part with solder in one operation.

However, when using this method, when taking out the immersed chassis, holes (
The problem is how to remove solder icicles, which can cause the insertion holes of feedthrough capacitors, etc.) to become blocked by solder (hereinafter this phenomenon is referred to as hole clogging), and solder icicles to form on the bottom edge of the chassis. becomes.

For example, conventionally, as described in JP-A-56-1044099, hole blockages and solder icicles are removed by centrifuging after immersion in solder. This method will be briefly explained below using FIG. 2.

FIG. 2 is a process diagram showing a conventional method for manufacturing a shielded chassis.

In FIG. 2, the manufactured chassis is immersed in an organic solvent such as chloroethane to degrease its surface, and then immersed in a flux bath to coat the surface with slack.

Next, after the entire chassis is immersed in the solder melting tank (step d), the chassis is placed in a centrifuge to remove any blockages such as holes, etc., while the molten half FB is not solidified (step e). To make the thickness uniform and to ensure the shielding of the fitting part between the chassis frame and the partition plate,
Oil immersion is performed (step f), and then the attached oil is removed again by chloroethane washing (step g).

However, in this method, since centrifugal separation is performed, it is necessary to perform a treatment for scattering the solder, and there may be drawbacks such as an increase in investment in peripheral equipment.

In addition, the shield at the fitting part between the chassis frame and the partition plate can be made relatively uniform and functionally easy without being immersed in oil by setting the direction in which the chassis is taken out in the direction in which the solder flows easily. No. Furthermore, in this method, in order to effectively perform cleaning after immersion in oil, organic solvents such as chlorotetraethane must be used.However, recently, these organic solvents have been Due to strict pollution regulations, it has become difficult to reuse them, and even if they could be used, there are drawbacks such as the need for capital investment in processing equipment.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to eliminate gaps that occur at the fitting portion between the chassis frame and the partition plate by soldering at once, without clogging the holes with solder or generating solder icicles. It is an object of the present invention to provide a method for manufacturing a shield chassis, which can be filled with the above-mentioned problems by shortening the number of steps and reducing the equipment cost.

[Summary of the invention]

When a chassis coated with slack is immersed in a solder melting tank, the coated slack separates from the chassis and forms a solder bath!
The solder surface mK of the ll tank floats to form a floating film. When the chassis that has been immersed through the floating film is taken out, the gaps that occur at the fitting part between the chassis frame and the partition plate are filled with solder, but the solder does not cover the holes or cause solder icicles. The inventor discovered something that cannot be seen.

The present invention has been made by focusing on this phenomenon. Therefore, in order to achieve the above-mentioned object, the present invention forms a floating film of flux on the surface of the solder in the solder melting tank in which the chassis is immersed. This process includes a first step and a second step in which the nine chassis immersed in the solder melting tank are taken out through the floating film of the slacks, and the holes on the side of the chassis are not clogged with solder or solder icicles are generated. In addition, solder is used to fill gaps that occur at the fitting portion between the partition plate that partitions the inside of the chassis frame and the frame.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a process diagram showing an embodiment of the present invention.

As shown in Figure wc1, first step a is to manufacture the chassis using the parts machining process and parts assembly process as in the conventional method.
), then in the first degreasing step, dirt and oil are removed from the surface of the chassis using chloroethane (step b), and then the entire seven palms are immersed in a flux bath (step c). In this flux application step, a tank containing flux having a relatively high softening point is used. After that, the chassis is taken out of the flux bath and placed in a high temperature atmosphere using a heater or the like for about 20 seconds to make the surface of the chassis ylK clean due to the cleaning action of the activation of the flux and to warm the entire chassis (Step C). ).

Next, the solder dipping step shown in step d in FIG. 1 will be explained with reference to FIGS. 5(a) and 5(b).

FIG. 3 is an explanatory diagram for explaining the solder dipping process in one embodiment of the present invention. (a) shows the state inside the solder melting tank before the chassis is immersed, and (b) shows the state inside the solder melting tank after the chassis is immersed.

In FIG. 3, 1 is a solder melting tank, 2 is a solder surface in the solder melting tank 1, 3 is a flux dispersion prevention frame, 4 is a dispersion prevention frame support means, 5 is a chassis, 6 is a flux floating film, and 7 is a chassis. It is a gripping means.

In the solder dipping process, first, the solder in the solder melting tank 1 shown in FIG. If it is a jet solder melting tank, the chassis 5 is immersed in the solder melting tank 1 with the jet temporarily stopped. It is best to immerse the chassis 5 into the solder melting tank 1 in line 5 immediately after the oxide film on the solder surface 2 has been removed, and it is necessary to immerse the chassis 5 in the solder melting tank 1 for about 5 seconds at most. This is an important point. This is because pinholes in the solder occur due to the adhesion of oxide scum to the surface of the chassis solder plating due to the oxide film.

Next, when the chassis 5 is immersed in the solder melting tank 1, the flux applied to the chassis 5 separates from the chassis 5 and floats to the solder surface 2 in the solder melting tank 1, where 7 fluxes float. A film 6 is formed.

This flux floating film 6 does not disperse much because the inside of the solder melting tank 1 is in a stationary state, but in order to ensure prevention of dispersion, the flux floating film 6 is placed on the chassis in advance as shown in FIG. 3(a). A dispersion prevention frame 3 (a frame with open top and bottom surfaces) larger than the outer size of the solder melting tank 1 is buried in the solder melting tank 1, and after removing the oxide film on the solder surface 2, as shown in FIG. 3(b)K, Solder surface 2
A part of the dispersion prevention frame 3 is extended to a human size length from above, and the chassis 5 is immersed in the dispersion prevention frame 3 for 5K. By doing so, it is possible to reliably prevent the flux floating film 6 from dispersing. Also, as another method, it is possible to make the solder melting tank 1 smaller so as to prevent dispersion.
On the solder immersion console, the larger the solder melting tank 1 is, the better the results will be because there will be less variation due to the relationship between heat radiation and the outside world. Furthermore, if it is desired to form an even thicker flux floating film 6, flux may be dropped onto the solder surface 2 within the dispersion prevention frame 3 from outside.

In this way, the flux applied to the chassis 5 floats away from the chassis 5, or the flux is dropped onto the solder surface 2 from the outside, forming a flux floating film 6 that is not dispersed. Above, immersed chassis 5
about 10 tm while passing the flux through the floating membrane 6.
/sec and take it out.

The chassis 5 taken out in this manner does not show any hole plugging caused by solder or generation of solder icicles.

This is probably due to the surface tension lowering effect of the flux or the gas generated from the flux, which prevents the holes drilled on the side of the chassis from being filled with solder drippings, or causes icicles to form at the edges of the chassis. It is thought that this is to prevent this, but we do not know for sure.

The immersed chassis 5 must be removed from the solder melting tank 1 before the flux floating film 6 on the solder surface 2 starts to carbonize.

For this reason, it is advantageous to use a flux with a high softening point because it can take a longer time.

The above is an explanation of the solder dipping process.

Next, in the cleaning process shown in step C in FIG.
The surface of the chassis was cleaned by immersing it in a 5% solution. Fine particles of flux and solder on the surface of the chassis can be easily removed with the solution without using chloroethane or the like.

〔Effect of the invention〕

According to the present invention, it is possible to manufacture a shield chassis by filling gaps that occur at the fitting portion between the chassis frame and the partition plate with solder all at once without clogging holes with solder or generating solder icicles. can. Moreover, compared to the conventional method, the number of steps can be reduced, the equipment cost can be reduced, and it can be easily realized. Furthermore, it is possible to process several chassis at once, greatly increasing productivity, and running costs are low because water and a 2-5% dilute hydrochloric acid solution are used instead of chloroethane. It's done.

[Brief explanation of drawings]

Fig. 1 is a process diagram showing an embodiment of the present invention, Fig. 2 is a process diagram showing a conventional shield chassis manufacturing method, and Fig. 3 is a process diagram illustrating a solder dipping process in an embodiment of the present invention. This is an explanatory diagram. Code explanation

Claims (1)

[Scope of Claims] 1) A manufacturing method for manufacturing a shielded chassis by filling a gap formed at a fitting portion between a partition plate that partitions the inside of a chassis frame and the frame with solder, the chassis being immersed. a first step of forming a floating film of flux on the surface of the solder in the solder melting tank; and a second step of taking out the chassis immersed in the solder melting tank through the floating film of flux. . A method of manufacturing a shielded chassis, characterized in that the gap is filled with solder without clogging holes or generating solder icicles on the side surface of the chassis. 2) In the method for manufacturing a shielded chassis according to claim 1, in the first step, the chassis coated with flux is immersed in a solder melting tank, so that the coated flux melts into the chassis. It is characterized by comprising either or both of the steps of forming a floating film by floating on the solder surface at a distance from the melting tank, or forming a floating film by dropping flux from the outside onto the solder surface in the melting tank. How to manufacture a shield chassis.