JP2584837Y2 - Jet solder bath - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet solder bath suitable for soldering a printed circuit board, particularly a printed circuit board on which chip components are mounted.

[0002]

2. Description of the Related Art Generally, soldering a printed circuit board on which chip components are mounted is performed in a jet solder bath having a primary jet nozzle and a secondary jet nozzle.

The primary jet nozzle jets a rough wave, and the rough wave penetrates between chip components mounted at high density and reaches a soldering portion which is a corner of the chip component. Can also penetrate, so that unsolder can be eliminated. However, the rough waves jetted from the primary jet nozzle move so violently that they form a bridge where the solder adheres to the adjacent soldering parts, and the solder is formed at the tip of the lead of the discrete component. This will form a icicle that adheres in a shape.

On the other hand, the secondary jet nozzle jets a quiet wave, and this quiet wave corrects a bridge or an icicle formed by the soldering of the primary jet nozzle.
This is to make the soldering part free from soldering defects.

That is, in the jet solder bath, even if a bridge or an icicle is formed by the primary jet nozzle, the bridge or the icicle can be easily corrected by the secondary jet nozzle. However, the generation of unsolder, in which the solder does not adhere to the soldered portion, is a serious problem since the electronic device does not function at all. For this reason, a large number of jet nozzles for eliminating unsolder have been conventionally proposed.

[0006] As a conventional jet solder bath for eliminating unsoldered solder, a moving body is installed in or on a nozzle, and a moving body is moved by external power to break a jet wave (Japanese Patent Publication No. Sho 62).
No.-46270, Japanese Patent Publication No. 1-34712), a method in which a resistor is installed in a nozzle to change the state of the jet of the solder flowing therethrough (Japanese Patent Publication No. 63-15063, Japanese Patent Publication No. 3-25268) Met.

[0007] By the way, in a jet solder bath in which a moving body is moved by power, the moving body must be moved in hot molten solder. However, there were drawbacks such as a shortened life. Also, in the jet solder bath with a resistor installed in the nozzle, the wave condition is always constant, that is, the peak is always a mountain, and the valley is always a valley, so the wave does not change and the solder of the chip component does not change. In some cases, the solder did not easily enter the attachment portion and became unsoldered.

The applicant of the present invention has invented and obtained a patent for a jet solder bath in which no wave is used and the shape of the wave is constantly changed so that the wave always enters the soldering portion of the chip component (Patent No. No. 1571242).

[0009] The jet solder bath, which was set up longitudinally elongated floating body jet outlet of the nozzle, the free body
Are stretched at both ends by tension springs, and the floating body vibrates due to the molten solder blown up from below the nozzle, and this vibration roughens the waves of the molten solder jetted from the jet port of the nozzle.

[0010]

The present invention is to provide a way, both of the floating body
In a jet solder bath whose ends are stretched by tension springs (hereinafter referred to as floating solder baths), the height of the jet is the same if the nozzle length is short, such as a radio, cassette tape recorder, or telephone. There was no problem with soldering to a small printed circuit board. However, when soldering a large printed circuit board such as a computer or a communication device using a long nozzle, unsoldering in which the solder does not adhere to the central portion of the printed circuit board sometimes occurs. An object of the present invention is to provide a floating-type solder bath that does not generate unsolder on a large printed circuit board.

[0011]

Means for Solving the Problems When the inventors of the present invention observed the jet state of the floating type solder bath with a long nozzle from the front, the waves jetted from the nozzle were not horizontal, and the center part was slightly smaller than both ends. Was lower. In other words, in a floating solder bath with a long nozzle, a large printed circuit board can come into contact with the molten solder that is jetted at both ends, but since the molten solder that is jetted at the center is low, it can no longer contact the molten solder. It becomes solder.

The inventors of the present invention have argued that why the long molten nozzle in the floating type solder bath reduces the central molten solder,
As a result of further investigation on the cause, it was found that the non-uniform vibration of the floating body installed at the nozzle outlet at the end and the center caused unsoldering at the center of the printed circuit board. Do you get it.

By the way, the wave of the molten solder jetted in the floating type solder bath becomes rough due to a phenomenon called "Kalman vortex street". The Karman vortex street means that when a rod is placed in a fluid flow, a number of vortices are formed around the flow of the fluid that collides with the rod. Due to the force of the vortex, the rod vibrates in a direction perpendicular to the flow direction, and this vibration disturbs the flow of the fluid.

In other words, the floating body type solder bath is designed to apply the Karman vortex streets to roughen the wave of the molten solder to be jetted, and the wave caused by this phenomenon becomes non-uniform. Very suitable for.

However, in a Karman vortex street, even if the rod vibrates, if the amplitude is large or small, where the amplitude is large, the flow of the fluid is hindered by the vibrating rod and becomes difficult to flow beyond it. , And more flows to the smaller amplitude.

In the floating body type solder bath, the longer the nozzle, the longer the floating body installed therein, and when the long floating body vibrates, the amplitude becomes larger at the center than at both ends. As a result, in the floating solder bath having a long nozzle, the height of the jet at the center becomes lower than that at both ends, and unsolder occurs.

Accordingly, the present inventors have completed the present invention by focusing on the fact that the height of the jet is constant if the amplitude of the floating body is the same in all parts even in a long nozzle in the floating body type solder bath. I let it.

According to the present invention, in a jet solder bath in which molten solder is jetted from a nozzle and a printed circuit board is brought into contact with the jet solder to mount a floating body elongated in the longitudinal direction at the nozzle outlet. At the same time, both ends of the floating body are stretched with tension springs, and
A jet solder bath characterized in that one vibration control piece for suppressing vibration of a floating body is installed at a substantially central portion of the floating body.

When the vibration control piece is installed on the idler, the vibration control piece hits the wall surface of the nozzle when the idler vibrates in the narrow nozzle, and large vibration cannot be made. Amplitude.

The vibration control piece used in the present invention can be of any shape as long as it can be installed on a floating body and can suppress the vibration of the floating body. The most suitable shape is a disk.

It is sufficient to provide one vibration control piece at substantially the center of the floating body to make the vibration of the floating body uniform.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a jet solder bath according to the present invention; FIG. 1 is an exploded perspective view of the jet solder bath of the present invention, FIG. 2 is an enlarged sectional view of a main part of the jet solder bath of the present invention, and FIG.
FIG. 3 is a diagram illustrating an installation state of a floating body.

The jet nozzle 1 comprises a pair of nozzle plates 2, 2 and side plates 3, 3 provided on both sides thereof. The upper part of the pair of nozzle plates 2 and 2 is vertical, the space between them is narrower, and the lower part is inclined to widen. Therefore, the molten solder S sent from below by a pump (not shown) is blown up from between the pair of nozzle plates 2 and 2.

A floating body 4 is provided between the pair of nozzle plates 2 in the longitudinal direction of the nozzle. The floating body is a thin rod-shaped body made of a material to which the molten solder does not adhere, for example, one made of stainless steel.

A vibration control piece 5 is provided substantially at the center of the floating body.
One is installed. The vibration control piece is a disk having a diameter slightly smaller than the narrow space above the pair of nozzle plates 2 and 2. The vibration control piece to be installed on the floating body is located approximately at the center of the floating body.
Number only are installed.

Here, a state in which the floating body is installed on the nozzle will be described. 1 and 3 illustrate the installation of the floating body. A mounting device 6 is installed on the side plates 3. The mounting device 6 has a hole 7 at one end larger than the diameter of the floating body.
Is a box-shaped body in which a screw hole 8 is screwed at the other end. The mounting device 6 is fixed with a screw (not shown) so that the notch 9 of the side plate 3 and the hole 7 coincide with each other.

When the floating body 4 is mounted on the mounting device 6, the end of the floating body is engaged with the tension spring 10, and the tension spring is further engaged with the bolt 11 screwed into the screw hole 7.
The bolt 11 is configured such that the tension of the tension spring can be adjusted by the degree of screwing. A lock nut 12 for preventing the bolt from being loosened is screwed to the bolt 11.

Next, the state in which the wave of the molten solder is roughened in the jet solder bath of the present invention will be described. The molten solder S sent from below the nozzle by a pump (not shown)
It is jetted from above the nozzles passing between the nozzle plates 2 and 2. At this time, since the floating body 4 is provided between the narrow nozzle plates 2, 2, Karman vortex streets are formed around the floating body, and the floating body vibrates laterally under the influence of these vortex rows. Since the floating body is made of an elastic material such as stainless steel to which the molten solder does not adhere, the vibration vibrates at a larger amplitude at the center than at both ends.

By the way, since the vibration control piece 5 is installed substantially at the center of the floating body, even if the central part of the play body tries to vibrate with a large amplitude, the vibration control piece hits the nozzle plate and large vibration cannot be made. . Therefore, the floating body vibrates at substantially the same amplitude at both the center and both ends.

If the amplitude of the floating body is the same over the entire length, the state in which the floating body obstructs the passage of the molten solder becomes the same, and the height of the jet from the nozzle plate becomes uniform.

[0031]

[Effect of the Invention] The jet solder bath of the present invention is a floating type solder bath capable of producing a jet wave most suitable for soldering chip components. Therefore, even when soldering a large printed circuit board, no unsoldering is generated at the center portion, and reliable soldering can be performed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a jet solder bath of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the jet solder bath of the present invention.

FIG. 3 is an explanatory view of a state in which a floating body is held by a tension spring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Nozzle plate 3 Side plate 4 Floating body 5 Vibration control piece 6 Mounting device

Claims (2)

(57) [Scope of request for utility model registration] In a jet solder bath in which molten solder is jetted from a nozzle and a printed circuit board is brought into contact with the jet solder to perform soldering, a floating body elongated in a longitudinal direction is installed at a jet port of the nozzle. , The idling
Both ends of the body are stretched with tension springs, and
A jet solder bath, wherein one vibration control piece for suppressing vibration of a floating body is provided at a central portion . 2. The jet solder bath according to claim 1, wherein the vibration control piece is a disk.