Vacuum attachment for electronic flux nozzle

A cylindrical body is provided over an ultrasonic flux nozzle. The cylindrical body contains a cavity inside generating a vacuum when the flux nozzle in in operation. Additionally, the portion of the top surface of the cylindrical body that is adjacent to the output of the flux nozzle has passageways for drawing off excess flux into the cavity. As a result, flux that exits the nozzle in an atomized vapor form is limited to a fine stream, thereby allowing the amount of flux to be deposited on a desired area to be precisely controlled.

FIELD OF THE INVENTION 
The present invention relates to the field of manufacturing tools for 
electronic devices, and more specifically, a vacuum attachment to be used 
in conjunction with an ultrasonic flux nozzle. 
ART BACKGROUND 
Most electronic devices are assembled by soldering their constituent 
components together. In the soldering process, a metal alloy is melted and 
used to join two adjacent metal surfaces together. The metallic surfaces 
which are to be joined are heated. The soldering material is then brought 
into contact with the heated surfaces. The alloy is chosen such that its 
melting point is fairly low. The solder is most often lead or tin based. 
The heated metallic surfaces causes the solder to become liquid and flow 
around the parts to be joined. When the solder cools and solidifies, a 
solid joint is thereby formed between the two elements. Because the 
joining medium is metallic, the soldering process result in a good 
electrical contact between the two elements which are joined. 
In order to facilitate the soldering process, a material known as flux may 
be brought into contact with the solder in order to induce the melting of 
the solder. Flux is a rosin based material. It is used to clean the 
metallic surfaces and free them of oxides. This results in better thermal 
contact between the elements to be joined and enhances the melting of the 
solder. 
In the past, solder was applied to the elements to be joined with a 
hypodermic needle means. During this process, a tremendous amount of 
excess, unused, flux was also deposited. The addition of flux to the 
soldering process has its disadvantages in that it can deteriorate the 
quality of the electrical contact between the elements which are joined. 
The excess flux must be removed via a cleaning process. This can involve 
the use of unwanted chemicals, such as freon. 
For this reason, it is desirable that the minimum amount of flux necessary 
to be used during the soldering process, and that the flux be accurately 
deposited at the desired location. Devices are known in the prior art 
which use ultrasonic methods to provide a fine spray of flux. This fine 
spray can be applied to a given area which is to be soldered. 
The ultrasonic devices typically consist of a relatively long, thin nozzle 
which is vibrated at a high frequency. Liquid flux enters the ultrasonic 
device and, as it passes through the nozzle, is broken into small droplets 
by the vibration of the nozzle. The small droplets exit the nozzle in the 
form of an atomized vapor spray. The ultrasonic devices reduce the amount 
of flux which must be used because the smaller elements of the flux can 
easily attach to the items which are to be soldered. These devices have 
the drawback, however, that they disperse the flux over a relatively large 
area and cannot be precisely aimed. As noted above, this may result in a 
poor electrical contact in the items which are to be joined, which could 
result in a deterioration of the operation of the overall assembly. Also, 
the need to clean the device is, for most cases, obviated. 
SUMMARY OF THE INVENTION 
The present invention overcomes the limitations of the prior art by 
providing a vacuum device which can be attached to an ultrasonic flux 
nozzle and which allows the amount of flux which is deposited on the 
desired area to be very precisely controlled. A cylindrical body is placed 
over the flux nozzle. The body contains a cavity inside which a vacuum may 
be generated. The portion of the top surface of the body that is adjacent 
to the output of the flux nozzle has passageways for drawing off excess 
flux into the cavity. When the ultrasonic flux nozzle in operation and 
when a vacuum is formed in the cavity, flux that exits the nozzle in an 
atomized vapor form is limited to a fine stream. Any flux that may tend to 
spread outward from the stream is drawn through the passageways and into 
the cavity by the vacuum pressure.

DETAILED DESCRIPTION OF THE INVENTION 
The following specification presents a description of a vacuum attachment 
for an ultrasonic flux nozzle. The vacuum attachment may be used to 
control the precision of the output of the nozzle. In the following 
specification, many details such as particular component arrangements and 
specific dimensions are described in order to provide a more thorough 
understanding of the present invention. It will be apparent to those 
skilled in the art, however, that the invention may be practiced without 
these specific details. In other instances, well-known components and 
functions are not described so as not to obscure the present invention 
unnecessarily. Moreover, the present invention is described in conjunction 
with an ultrasonic flux nozzle because the present invention is designed 
to be used with such a device. It is to be understood, however, that the 
ultrasonic flux nozzle is not an element of the present invention. The 
present invention consists only of the vacuum attachment as described and 
claimed. 
Referring first to FIG. 1, a perspective view of the present invention is 
shown. In FIG. 1, the vacuum attachement is shown partially cut away so as 
to reveal the interior details of the device. The vacuum attachment 10 is 
placed over the nozzle 100 of the ultrasonic flux device 101. With most 
ultrasonic flux devices, the nozzle 100 is generally shaped in the form of 
an extended cylinder. With the ultrasonic flux device, flux enters the 
bottom of the nozzle 100 in liquid form. Pressure causes the flux to 
travel upward through the nozzle towards its end 102. A suitable mechanism 
(not shown in FIG. 1) is provided to vibrate the nozzle 100. This 
vibration takes place at a very high frequency. The vibration causes the 
liquid flux to break up into tiny droplets which exists the nozzle 100. 
The flux exits in an atomized vapor spray form through the opening 103 in 
the tip 102. The ultrasonic flux nozzle atomizes particles to the 20 to 50 
micron range. By shaping the tip 102 and opening 103 in certain ways, the 
flux can be made to disperse in a given pattern. It has been found that 
the exact shape and extent of such a pattern cannot be adequately 
controlled in a sufficient manner. Without the vacuum attachment of the 
present invention, therefore, excess flux may travel in any random 
direction, which lends to unwanted flux deposition on the elements that 
are to be soldered together. 
As noted above, the vacuum device 10 is placed over the nozzle 100. In the 
preferred embodiment, the vacuum device 10 is substantially cylindrical in 
shape and is made up of an elongated body 12. A central hole 14 is present 
to provide access for the nozzle 100. A number of openings 50 are formed 
into the top surface of the body 12. These openings allow access to a 
cavity 42 formed within the body. A vacuum source (not shown) is coupled 
to the body 12 through the exhaust holes 52. 
Referring next to FIG. 2, a cross-sectional view of the preferred 
embodiment of the vacuum attachment means is illustrated. In this view, 
the vacuum attachment 10 is shown mounted on the ultrasonic flux device 
101. The nozzle 100 of the ultrasonic flux device extends upwards through 
the central hole 14 in the vacuum attachment 10. In the preferred 
embodiment, a cylindrical outer wall 40 couples with the ultrasonic flux 
device 101 as shown. An upper member 44 and lower member 48 protrude 
radially inward from the outer wall 40 towards the nozzle 102. These upper 
and lower members combine with inner cylindrical wall 49 to define a 
cavity 42 within the vacuum device. 
In FIG. 2, the upper member 44 and lower member 48 appear to be straight 
members. When viewed from above, these elements are actually shaped as 
disks because the entire vacuum unit is cylindrical in shape in the 
preferred embodiment. Although the body 12 of the vacuum attachment 10 in 
the preferred embodiment is cylindrical in shape, it will be appreciated 
by those skilled in the art that the present invention is not limited to 
such a shape. Other arrangements may be used, so long as the body 12 
surrounds the nozzle 102. 
An inner support member 45 extends upward from the top member 44 and angles 
inward toward the nozzle 102. This support member 45 is used as an 
alignment means to position the vacuum unit 10 on the ultrasonic flux 
device 101. As with the outer wall 40 and inner wall 49, although there 
appear to be two support walls 45 in FIG. 2, the entire device is circular 
so that a single support wall 45 actually travels the entire circumference 
around the nozzle 102. Other positioning means may be used with equivalent 
results. For example a rubber grommet may be placed in the central hole 14 
to align the vacuum attachment on the nozzle. 
At least one exhaust hole 52 is formed within the outer wall 40. The 
exhaust hole 52 provides a passageway between the interior cavity 42 and 
the outside of the vacuum coupling 10. A vacuum source (not shown in FIG. 
2 but illustrated schematically in FIG. 1) is attached to the exhaust hole 
52. This vacuum source causes a low pressure vacuum to be formed within 
the cavity 42. FIG. 2 illustrates two exhaust holes 52. In the preferred 
embodiment there are actually three exhaust holes spaced at equidistant 
intervals. The vacuum source is coupled to each of these exhaust holes. 
This arrangement provides for balanced pressure levels within the cavity 
42. It will be appreciated by those skilled in the art that a different 
number of exhaust holes may be provided with equivalent results. The flux 
is drawn through the exhaust holes. A filter means is provided outside of 
the vacuum unit (not shown in FIG. 2) to filter the flux vapor out of the 
airflow. 
Formed within the top member 44 are a plurality of openings 50. These 
openings 50 are used to draw off any excess flux which has been 
transformed into the aerosol state as described above. The operation of 
these openings 50 will be described more fully below. 
Coupled to the inside of the outer wall 40 and within the cavity 42 is a 
circular shelf 46. The shelf 46 is used to balance the air pressure at all 
points within the cavity 42. Shelf 46 accomplishes this task by preventing 
laminar fluid flow between the exhaust ports 52 and the nearest opening 
50. In this manner, the vacuum pressure is substantially balanced at all 
of the openings 50. This arrangement enhances the overall operation of the 
vacuum attachment 10. 
The operation of the vacuum attachment is quite straightforward. A user 
simply places the device on the ultrasonic flux device 101. The ultrasonic 
flux device 101 is turned on. As described above, this results in a fine 
atomized vapor spray of flux being emitted form the opening 103 at the end 
102 of the nozzle 100. It is most often desirable that this flux move in a 
straight line axially outward away form the nozzle 100. Excess flux may 
also move radially outward from the end of the nozzle, as noted above. In 
that case, the excess flux will travel over the openings 50 in the vacuum 
attachment. The vacuum in the cavity 42 will cause a low pressure region 
to be formed above the openings 50. The flux will be drawn towards this 
low pressure region and into the cavity 42. Thus, with the present device, 
excess flux is not allowed to be deposited on the elements of the 
electronic units which are to be soldered together. This allows the flux 
to be accurately positioned and allows the use to carefully control the 
amount of flux which is used. 
The foregoing has described a vacuum attachment for an ultrasonic flux 
nozzle. This description has been made with reference to specific 
exemplary embodiments thereof. It will be appreciated by those skilled in 
the art that various departures from these embodiments can be made without 
departing from the overall spirit and scope of the present invention. Some 
of these changes have been described. Others are possible. The full scope 
of the present invention is limited only by the following claims.