JPH0632844B2 - Soldering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soldering apparatus, and in particular to a system in which a component to be coated with solder passes through a solder bath. The present invention is particularly, but not exclusively, concerned with the application of solder to the leads of integrated circuit packs such as dual in-line (DIP), SOIC or other types.

Often such coatings are performed in a fluidized soldering system. In such a system a carrier for the components can be passed over the solder bath in which the waves standing are formed. The arrangement is such that the portion of the component to be coated passes over the top of the wave of solder as the carrier moves over the bath.

A problem with some known systems is that it is difficult to control the quality of the coating, especially for uniform thickness. Often the package leads have areas where the coating is significantly thicker than anywhere else. Another problem is that of adapting to a variety of different types of handleable parts, especially with regard to immersion depth in waves of solder. For example, D
IP requires a 6 mm depth of immersion, whereas SOIC designed for surface mounting on circuit boards, for example, only 1.2 m
You can request a depth of m. To accommodate such depth ranges, it may be necessary to change the wave height or to use separate equipment dedicated to individual components.

A system has been proposed for vertically dipping individual carriers and then removing them vertically from the solder bath.
This offers an improvement in quality over the fluid soldering equipment, but has the drawback of being considerably slower because the carrier cannot be processed continuously.

Therefore, there is a need for a system that achieves some of the benefits of both flow soldering and immersion soldering, so as to provide reasonable quality and reasonable work speed, and preferably greater flexibility. .

The present application discloses an electronic integrated circuit pack mounted on a horizontally arranged carrier including a solder bath, a track for guiding the carrier across the solder bath, and means for propelling the carrier along the track. An apparatus for applying solder to the leads of the carrier, the track comprising a first contoured area for guiding the leading portion of the carrier downwardly toward the surface of the solder, and a longitudinal section from the first contoured area. Directionally and having a second contoured area for guiding the tail portion of the carrier downwards towards the surface of the solder, and the contours of said first and second contoured areas are substantially the same, The carrier comprises first and second followers for respectively supporting a leading portion and a trailing portion of the carrier on a guide track, the first and second contour areas of said guide track being laterally offset from each other, And The longitudinal spacing between them is equal to the longitudinal spacing between the first and second followers of the carrier laterally offset from each other, so that the carrier moves vertically toward and away from the surface of the solder. The device is disclosed, characterized in that it maintains its horizontal orientation.

With such a device, the parts are subjected to a vertical dip, but at the same time the bath is moved laterally. Continuous use can be achieved by the subsequent use of multiple carriers on orbit. Vertical dipping gives good quality coatings, and speed and descent depth can be determined by the contours of specific areas of the track.

The significance of providing separate, spaced-apart contoured areas for the leading and trailing portions of the carrier is that it is dipped across the solder bath and maintained in a horizontal configuration during movement. If the leading and trailing edges were the only contour areas that followed sequentially, the carrier would tilt as it moves toward and away from the solder surface. This will result in uneven and poor quality coating.

Usually the carriers will be guided by trajectories on either side, each trajectory having the areas with the contours mentioned and of course aligning them.

The contours in each contour area generally consist of a downwardly sloping area, a horizontal area and an upwardly sloping area. The slope of the sloped area determines the rate of descent and ascent, and one can be larger than the other if desired. The sloped areas can be flat or have more complex contours to provide varying descent and / or ascent rates.

The two contoured areas on the track can be laterally offset and the corresponding followers supporting the leading and trailing portions of the carrier can likewise be laterally offset with respect to each other. This allows the lead follower to bypass one area and continue to travel on the flat portion of the track until it reaches its associated contour area. At this point the tail follower will reach its relevant contour area. After the dipping operation, the trailer follower will bypass the next contoured area and continue on the flat area of the track.

The follower may be in the form of a wheel, roller, non-rotating low friction element, etc., for example. The follower may be integral with the carrier, attachable to the carrier, or part of a movable support for the carrier.

The carrier itself may be of any suitable type, for example of the type shown in European Patent Application 0171257,
If desired, it may be modified to operate in the apparatus described herein.

The means for propelling the carrier along the track may be of any suitable form, but one preferred embodiment comprises a chain conveyor having multiple fingers for engagement with the carrier. The carrier can include notches for receiving fingers. The fingers must have sufficient vertical limit to remain in contact with the carrier during the dipping operation. Alternatively, the carrier can have a portion of the vertical limit sufficient to remain in contact with the shallow finger or similar member.

It is most advantageous if the contoured portion is replaceable. In this way descending and ascending depth and velocity,
Furthermore, by varying the total immersion time, it is easy to adapt the device to different parts. Each contoured portion may be provided on a separate replaceable member, but preferably the pair of areas concerned is provided on a single replaceable member such as a block. This is a considerable benefit over flow soldering systems where the height of the waves has to be changed.

Embodiments of the inventive device will now be described by way of example and with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a guide track used in the apparatus.

FIG. 2 is a sectional view through a part of the apparatus.

Referring in detail to the drawings, FIG. 1 shows a left guide track 1 in the form of an L-section angle bar and a corresponding right guide track 2 also in the form of an L-section angle bar. On the device, tracks 1 and 2 are arranged in parallel for guiding the carriers in the direction of arrow A. Orbit 1 and 2
Has aligned notches 3 and 4 of lower guide surfaces 5 and 6 suitable for accommodating contoured blocks 7 and 8, respectively. These blocks are removably arranged in the notches by suitable means so that they can be exchanged to provide different contours. The blocks are provided with indentations, as indicated at 9, so that their upper surfaces 10 and 11 are flush with the surfaces 5 and 6 of the tracks 1 and 2, respectively, when housed in the cutouts 3 and 4. Let's do it.

Referring to a block, it has a leading contour area 12 formed on the left hand or outside of the leading end of the block. This contoured area consists of a downwardly sloping ramp 13 descending from the upper surface 10, a horizontally extending portion 14 and an upwardly sloping ramp 15 extending to the upper surface 10. The width of this area is about half the width of the block.

The block 7 has a tail contour area 16 formed on the right hand or inside the tail end of the block, again having a width of about half the width of the block 7. The trailing contour area 16 is thus laterally offset from the leading contour area and has the same shape and size as that of the leading contour area 12, and is inclined downwardly to a ramp 17, a horizontal portion 18 and an upper portion. It has a ramp 19 that tilts to.

The distance between the start of the ramp 17 and the start of the ramp 13, and thus all other corresponding contour parts, is
Equal to the spacing between the leading and trailing followers that support the carrier and follow the leading and trailing contours, respectively. Thus, assuming that the carrier is horizontal when the follower moves along the level surface 5 of the track 1, it will descend and rise according to the contour, but will remain horizontal when the follower passes through the contour area. .

The right-hand block 8 is an exact mirror image of block 7, the contour areas 19 and 20 each having the same contour.
Mirror images of 2 and 16. Blocks 7 and 8 are vertically aligned on trajectories 1 and 2. This allows the right-hand follower aligned with the left-hand follower to follow the contours at the same time and ensure that the supported carrier always remains horizontal.

Referring now to FIG. 2, the left hand side of the soldering device is shown. The left track 1 is arranged horizontally and has an angle 21
It is attached to the frame 20 by. The track 2 runs along the sides of a solder bath 22 containing solder with a liquid surface 33. On top of the bath 22 a carrier 24 for the parts, for example of the type shown in European patent application 0171257, is installed. The carrier 24 has a central area 25 in which the components are mounted on their tracks with their leads downwards, and a support 26 on the left-hand side thereof. Directly below this support 26, outside the support 26, a lead follower in the form of a rotating wheel 27 in a bearing block 28 is mounted. Also provided inside the support 26 is a rear follower in the form of a rotating wheel in the bearing block 30. Wheels 27 and 29 run along surface 5 of track 1. However, the wheels 27 are arranged to follow the contour in the area 12 of the block 7, and the wheels 29 are
Are arranged so as to follow the contours in the area 16. As can be appreciated, the leading block 28 and wheels 27 are provided in front of the carrier 24, and the inwardly spaced aft block 30 and wheels are provided at the rear of the carrier.

Wheels move along track 1 and areas 12 and 16
Carrier 2 when following their respective contours in
4 is maintained in a horizontal position, but is dipped into the solder for a sufficient amount to cover the required part of the part and then pulled up.

The movement of the carrier is attached to the frame 20, including a chain link 31 passing through an idler sprocket (not shown) and an electric motor driven sprocket (not shown) through a chain guide 32. It is realized by a chain conveyor. The drive speed can be adjusted. On the chain conveyor is provided an arm 33 having a hanging finger 34 that engages the support 26 of the carrier 24, for example by being housed in a slot in the left-hand end of the support. The depth of the fingers 34 is adapted to maintain engagement with the support 26 as the carrier 24 descends and rises. Usually a large number of carriers will be processed sequentially and each will be moved by each of the longitudinally separated fingers.

The right-hand side of the device using track 2 corresponds exactly to the left-hand side, except that it is not necessary to provide a second drive mechanism. In the absence of a second drive mechanism, which is usually arranged in a link or otherwise to the first, it may be desirable to provide a guide to help direct the carrier under the track in a straight line. .

The particular structure described and illustrated has numerous benefits that also apply to other systems that employ at least some of the features and ideas that have been introduced. This device has great flexibility and can be used to solder to all types of semiconductor leads from the smallest SOICs to long lead components and power transistors. This system, which includes vertical movement and vertical dipping but maintains a horizontal orientation, is very flexible but gives good results.
Since constant movement can be maintained, the power output is at least as good as the result obtained by fluidized soldering and can be increased to a level better than the result obtained by static immersion. Dross production can be reduced compared to flow soldering systems.

It will be appreciated that this disclosure embodies a number of inventive features and that variations and modifications are possible while also retaining at least some of the benefits described. The invention also extends to a method of coating a part using a system for maintaining a horizontal orientation and a part so coated. Furthermore, the solder bath can be replaced by a bath of another fluid such as a flux or, in fact, any fluid in common applications.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a guide track used in the apparatus, and FIG. 2 is a sectional view of the apparatus. 1, 2 are guide tracks, 12 and 19 are leading contour areas, 16,
20 is a tail contour area, 22 is a solder bath, 24 is a carrier,
Reference numerals 27 and 29 are rotating wheels, and 28 and 30 are bearing blocks.

Claims (6)

[Claims] 1. A carrier having a horizontal position in which an electronic integrated circuit pack is mounted so that a lead wire is directed downward and can be freely taken out.
A lead wire soldering device for an electronic integrated circuit pack, comprising: a solder bath; a guide track for guiding the carrier across the solder bath; and means for propelling the carrier along the guide track. The carrier has a first follower for supporting the leading part of the carrier on the guide track, and a second follower longitudinally separated from the first follower and supporting the rear part of the carrier on the guide track. The guide track includes a first contoured area for guiding the first follower downwardly toward the surface of the solder, and a longitudinally spaced area from the first area and a second follower. A second contoured area for guiding downwards towards the surface of the solder, the first follower bypassing the second contoured area and the second contoured area when the carrier is propelled along the guide track. The follower bypasses the first contour area. As to the first and second contour zone of the guide track are offset laterally from each other,
Similarly, the first and second followers supporting the leading and trailing portions of the carrier are also laterally offset from each other, and when the carrier is propelled along the guide track, the carrier keeps its horizontal position and the integrated circuit. The first and second contoured areas are of the same shape, and between the first and second contoured areas, such that they approach and leave perpendicular to the solder surface for dipping the leads of the pack into the solder bath. The vertical spacing between the first and second followers is equal to the vertical spacing between the first and second followers. 2. The apparatus according to claim 1, wherein the guide tracks are provided on both sides of the solder bath. 3. The apparatus of claim 1 or 2 wherein the first and second contoured areas comprise a downwardly sloping area, a horizontal area and an upwardly sloping area. 4. The means for propelling the carrier along the track comprises a chain conveyor having a plurality of fingers for engaging the carrier.
The device of paragraph. 5. The device according to claim 1, wherein each contoured area is formed by a block removable from the guide track. 6. The apparatus of claim 5 wherein the guide track has a notch into which the block having the first and second contoured areas of the guide track is replaceably received.