WO2003035319A1

WO2003035319A1 - Desoldering wick dispenser

Info

Publication number: WO2003035319A1
Application number: PCT/US2001/045338
Authority: WO
Inventors: William H. Strater
Original assignee: Tech Spray, L.P.
Priority date: 2001-10-23
Filing date: 2001-10-23
Publication date: 2003-05-01

Abstract

A desoldering wick dispenser has a housing (10) with a coil (16) of desoldering wick in the housing. A tube (313) is connected to the housing (10) and an end portion of the wick extends from the coil through the tube (313) to protrude beyond the end of the tube. Preferably the tube is formed of helically wound stainless steel wire. The wick is manipulated by the tube which may be bent by a finger when the dispenser is used. In one embodiment of combined housing and tube, the housing has a funnel shaped face with a central aperture. An end portion of the desoldering wick extends through a tube extending from the center of the housing. The coil (16) of desoldering wick is a spiral having a conical shape approximately complementary to the end (14) of the housing. Alternatively, the coil may be a helically wound spool of wick in a somewhat more elongated tubular housing. In another embodiment, the desoldering wick dispenser includes a conventional wick package in the form of a bowl and a cover, and having a gap between the edge of the cover and the outer edge of the bowl. A desoldering wick is coiled in this housing and an end portion of wick passing through the gap is drawn through a tube. Alternatively, wick may be drawn through a tube connected tangentially to a housing containing desoldering wick.

Description

DESOLDERING WICK DISPENSER

BACKGROUND

This invention relates to a dispenser for wick used for absorbing molten solder. It is fairly common in the electronics industry to remove solder from a printed circuit board. This may be needed, for example, when a component has been removed and is to be replaced by a different component. For many years, solder has been removed by placing a copper wick on the solder and touching it with a hot soldering iron. Such wicks are typically a braid of copper wire having open space for receiving solder. More recently, desoldering wicks have been made of what amounts to woven screen wire folded in multiple layers, leaving space within the mesh and between layers of the mesh for receiving molten solder. Typically, the desoldering wick has a thin layer of flux so that when the solder melts, it is drawn into the wick by capillary action.

Short lengths (e.g. 1.5 m.) of desoldering wick are available in disk-like plastic packages containing a flat spiral of desoldering wick. A typical package has a dish-shaped half with a hollow central hub (somewhat like an angel food cake pan). A flat "cover" is secured to the hub and fits closely near the outer edge of the container. An end of the desoldering wick is pulled through the narrow gap around the edge of the cover. The desoldering wick is unwound from the outside of the two dimensional spiral of wick that surrounds the hub. The user typically holds the dispenser with a short length of protruding wick which is touched against the solder to be removed. Such a dispenser is illustrated in U.S. Patent No. 3,430,886.

It is desirable to provide a dispenser for desoldering wick which is easily handled. Furthermore, it is desirable for the dispenser to have an elongated guide for the desoldering wick to permit it to reach into tight spaces for removing solder.

BRIEF SUMMARY OF THE INVENTION

There is, therefore, provided in practice of this invention according to a presently preferred embodiment, a desoldering wick dispenser having a housing with a coil of desoldering wick in the housing. An end portion of the wick extends through a tube for manipulating the wick during use. In one embodiment a conventional package contains the coil of desoldering wick. In another embodiment, there is a central aperture in the end of the housing and the tube containing an end portion of the wick extends away from the aperture. Another embodiment has a housing with a tube extending tangentially from the housing.

For example, in one embodiment the housing is funnel shaped with the tube extending from the center of the funnel. The coil of wick is in the form of a conical spiral and the end of the wick extending through the tube is drawn from adjacent the center of the coil. If desired, the tube may be formed of an elastically bendable helical coil of wire.

DRAWINGS

FIG. 1 illustrates a desoldering wick dispenser in longitudinal cross-section;

FIG. 2 is an end view of the dispenser of FIG. 1;

FIG. 3 illustrates in longitudinal cross section a second embodiment of desoldering wick dispenser;

FIG. 4 illustrates in a partly cutaway view another embodiment of desoldering wick dispenser;

FIG. 5 illustrates in longitudinal cross-section another embodiment of desoldering wick dispenser;

FIG. 6 is a side view of an alternative embodiment of desoldering wick dispenser;

FIG. 7 is a face-on view of an embodiment of desoldering wick dispenser using a conventional housing;

FIG. 8 is a side view of the embodiment illustrated in FIG. 7; and

FIG. 9 is a side view of a plastic part snapped into a housing in the embodiment of FIG. 7.

DESCRIPTION

In a first embodiment the desoldering wick dispenser is in the form of a funnel-shaped housing 10, having an enlarged hollow body 11 and a protruding axial nose 12. A tube 13 is inserted into the end of the nose portion of the housing and extends a few centimeters so that the total length of the nose and tube portions is in the order of ten cm. This turns out to be a convenient length for handling the dispenser. The tube may be longer on a commercial product, giving the user an opportunity to shorten the dispenser by snipping off a portion of the tube.

The housing has a generally conical end face 14 around a central aperture through the nose portion. There is a smoothly rounded surface between the tapering end face and the inside wall of the aperture.

The tube inserted into a socket in the end of the nose may be heat resistant plastic held in place solely by friction or it may be adhesively bonded to the injection molded housing. Alternatively, the tube maybe a metal, such as aluminum or stainless steel, which is not wettable by molten solder. A metal tube may be longitudinally slit and slightly larger in diameter than the socket in the end of the nose. Such a tube is squeezed to a slightly smaller diameter and springs out against the inside of the nose to secure the tube in place. A metal tube may also be adhesively bonded to a plastic housing. If desired, the tube may be integral with the housing, i.e., the nose of the funnel shaped housing is elongated to a desired extent. A conical coil 16 of desoldering wick fits into the circular housing. An end of the wick drawn from adjacent the center of the spiral coil extends through and slightly beyond the end of the axial tube 13. The desoldering wick may be a conventional braid of copper wire, a knitted wick, or preferably multiple layers of folded copper screen mesh. Any of such embodiments has a thin coating of solder flux. Desoldering wick is used in sizes 1, 2, 3, 4, 5 and 6 with the numerals indicating the approximate width of the desoldering wick in millimeters. About 90 percent of the usage is in sizes 2, 3 and 4. Any of these sizes are suitable for fitting into the housing of the desoldering wick dispenser. The housing can readily be made deep enough to accommodate a wide embodiment of desoldering wick and at the same time, quite satisfactorily contain wick with a narrow width. An exemplary desoldering wick has a thickness of about 0.4 mm. A housing as described can readily accommodate and dispense 2.5 to 5 meters of desoldering wick.

A dome shaped cover 17 snaps into the open end of the funnel shaped housing to close it and protect the desoldering wick. The convex face of the dome shaped cover conforms more or less to the conical coil of desoldering wick to keep it in place. The cover can economically be made from a circle of stiff paper with a radial slit so that it can be deformed into a shallow cone and snapped into the end of the housing.

An operator uses the desoldering wick by gripping it around the narrow perimeter of the housing and directing the tube toward a spot where solder is to be removed. Alternatively, the housing maybe "palmed" and the tube directed with the operator's fingers. Other operators may prefer to hold the dispenser with the fingers on the tube, more like one holds a pencil.

A bit of desoldering wick extends beyond the end of the tube. The amount drawn from the coil and pulled out of the end of the tube is determined by the operator, as required. For a particular task, the wick can be drawn out of the tube by fingers or preferably by conventional clippers. Such clippers are used to snip off an end of the wick after it is used and engorged with solder. Thus, in a single operation, the clippers can draw out enough wick for the next desoldering job and the already used end snipped off. By drawing the wick in this manner, it is not necessary to touch it with the fingers.

The elongated tube on the housing permits the operator to place the desoldering wick in a precise location on a circuit board or the like. The tube permits such placement in narrow spaces between components which may be crowded together on densely packed circuit boards.

Conventional coiled wick on spools or in prior dispensers is typically advanced by grasping the wick with one's fingers and pulling from the spool. This contaminates the flux and leaves a deposit of flux on the fingers of the operator.

The included half angle between the conical end face and the axis of the dispenser is in the range of from 45° to 75° and is preferably about 65°. The angle of the cone of desoldering wick in the housing has approximately the same angle as the housing. It is found that such an angle (rather than a flat coil) enhances the drawing of desoldering wick from near the center of the coil without hindrance by friction or tangling.

The spiral coil of desoldering wick is easily wound as a two dimensional spiral. The coil is placed in the housing and a conical tool, or just the convex cover, is pressed in to deform the coil to approximately match the taper on the end of the housing. An end of the desoldering wick near the center of the coil is then pushed or pulled through the nose and tube. The dome shaped or conical end cover can then be snapped in place.

FIG. 3 illustrates a second embodiment of desoldering wick dispenser which resembles the first embodiment, but employs a three dimensional spool of desoldering wick instead of an essentially two dimensional spiral coil of wick. In this embodiment, the circular housing 110 is elongated and has a somewhat smaller diameter than the housing illustrated in FIG. 1. A tube 113 is pressed into an extending nose portion 112 of the housing. An end cover snaps over the opposite open end of the housing.

A coil of desoldering wick 116 is contained within the housing and an end 120 of the wick extends through and out of the end of the tube. This coil of desoldering wick is wound as a spool having successive layers of right hand and left hand helixes of wick. Such an elongated coil of wick can be wound using a mechanism similar to what is used for guiding line on a fishing reel. The end portion of the wick extending through the tube is drawn from the inside of the coil similar to the way string is pulled from the center of a ball of string. A greater length of desoldering wick can be contained in such a three dimensional coil than in the essentially two dimensional coil in the housing of the first embodiment. This is particularly true for the narrower widths of desoldering wick.

With wider widths of wick, an increased weight may make the coil unduly heavy. An excess amount of desoldering wick stored in the dispenser may make the back end heavy and not as comfortable to handle by the person using the dispenser. An increased weight may, however, be offset by the convenient shape where the housing has a smaller diameter and is elongated.

Figure 4 illustrates a desoldering wick dispenser employing a conventional package for the wick. The wick containing package comprises a dish-shaped or bowl-shaped body 210 with a hollow central hub 211 (somewhat like an angel food cake pan). The bowl has a typical diameter of about 4.7 cm. and is about one cm. deep. An approximately flat cover 212 snaps onto the hub and fits closely near the outer edge of the body, leaving a narrow gap 213 around the edge of the cover. The desoldering wick 214 is wound in a two-dimensional or flat spiral around the central hub (before the cover is placed on the body). The wick is unwound from the outside of the spiral of wick that surrounds the hub. The end of the wick is drawn through the gap around the edge of the cover and is slightly pinched by the close fit between the cover and the body so that it does not freely unwind. Such a dispenser is illustrated in U.S. Patent No. 3,430,886, which is hereby incorporated by reference.

The end of the desoldering wick unwound from the spiral is passed through a tube 216 so that the end 217 of the wick extends beyond the end of the tube. A convenient tube length is about 5 to 7 cm. The diameter of the tube is enough to provide some friction against the wick, for the particular size wick employed (from about 1 to 6 mm, most commonly 2, 3 or 4 mm). The friction is enough to prevent the wick from falling from the tube, but not so much that it is hard to draw the wick through the tube. When this embodiment is used, the wick is held by means of the tube so that the wick can be placed in a precise location on a circuit board or the like. The package with coiled wick inside is readily "palmed" or left dangling from the end of the tube as the tube is held much like one holds a pencil. The friction between the cover and body engaging the wick is enough to support the package.

After solder is sucked into the wick, a little more can be pulled out of the package, and the additional length pulled through the tube a little further with clippers and the end snipped off. By using a tube in combination with the conventional package, almost the entire length of wick may be used before discarding the final "tail". The wick is manipulated by the tube even after the inside end is pulled out of the package. The tube keeps the operator's fingers cool. By being careful not to pull out too much of the unused wick, even a short remaining bit of wick may be used. With a plastic tube, the sides can be pinched against the wick to add friction as the wick is pulled out.

The embodiment of desoldering wick dispenser illustrated in FIG. 5 is the same as that illustrated in FIG. 1, except for the tube 313 through which the wick is dispensed. In this embodiment the tube is fabricated from stainless steel wire helically wound into a coil spring about 5 to 6 cm long. Preferably, the coils of the spring are essentially tight against each other for the major portion of the length of the tube. Near the end remote from the housing, i.e., the end from which the wick is dispensed, it is preferred to space the some of the coils 325 a short distance apart (about 0.05 to 0.5 millimeter) for minimizing heat transfer along the length of the spring.

In an exemplary embodiment the spring is wound with one half millimeter diameter stainless steel wire. An exemplary tube has an inside diameter of about 2.6 to 2.7 mm. A desoldering wick having a nominal width of 3.5 mm can be fitted through such a tube. The wick is generally flat and is buckled somewhat to a width that will fit through a tube having an inside diameter smaller than the nominal width of the flat wick. Smaller widths of wick, of course, fit through the tube easily. The total length of tube beyond the wick housing is about 5 cm. A few turns near the outer end are tight against each other, and approximately the next nine mm of coils are spaced apart about 0.1 mm. Preferably, the spring forming such a tube is wound with a left hand turn. The spring is screwed into the housing, much as a screw is threaded into a hole, to the depth of an internal shoulder. It is found that a small burr left from snipping off the wire when making the spring digs into a plastic housing and inhibits inadvertent unscrewing of the spring from the housing. More significantly, the left hand winding of the spring inhibits removal. Due to years of exposure to right hand threads, people attempt to remove the spring by turning in the direction of a right hand thread, which, of course, doesn't work. Although a spring tube maybe removed by unscrewing as a left hand thread, people rarely think of that.

An advantage of a desoldering wick dispenser with a spring for a dispensing tube is the ability to elastically bend the tube to fit into tight places. When bending force is released, the spring straightens. If desired, such an embodiment may be made with a more ductile material than stainless steel, such as aluminum or plastic, so that a persistent bend may be made for dispensing wick through a bent tube. With a more ductile material for the spring, such a bend may be changed or reversed for use of the dispenser in various situations. Alternatively, one may make a dispenser with a tube that is originally bent or crooked instead of straight.

Stainless steel is exemplary of equivalent metals that have high modulus of elasticity and yield point for making a spring, and which are not wettable by molten solder. Aluminum is exemplary of equivalent metals and plastics that maybe plastically deformed to form a bent tube that is not wettable by solder.

Many modifications and variations of a desoldering wick dispenser as described hereinabove will be apparent to those skilled in the art. For example, a somewhat different coil of desoldering wick may be placed in a housing similar to that illustrated in FIG. 3. Such a coil may be a single layer of helical winding of desoldering wick, with the portion of the wick extending through the tube being drawn from an end of the coil nearer to the tube. Such a coil may be made, for example, by winding a single helix of a hollow braid and then compressing the coil longitudinally for flattening the braid.

FIG. 6 illustrates another embodiment of desoldering wick dispenser which is economical and easily manipulated. The dispenser has a generally circular housing 410 with a hollow nose 412 extending tangentially from one edge. The housing is preferably flat or disc-shaped. It is easily made from two generally similar mirror-image halves of plastic, snapped together. With such an arrangement, the two halves can be made by a straightforward molding technique. The housing is hollow, as indicated by the dashed line 414 indicating the perimeter of the inside of the housing, which generally mimics the exterior.

A tube 416 in the form of a helical winding of wire which is not wettable by molten solder, such as stainless steel wire, is held in a cavity in the nose of the housing. A generally flat spiral coil of desoldering wick 415 fits loosely in the circular portion of the housing. The inside of the housing is preferably flat to conform to the shape of the coil of wick and minimize opportunity for tangling as wick is pulled from the outside of the coil. An end of the desoldering wick from the outside of the spiral coil extends through the nose and helically wound tube so that the end 418 extends a short distance beyond the end of the tube. Such a tube is essentially the same as described and illustrated with respect to the embodiment illustrated in FIG. 5.

This embodiment may be used by holding the housing in the palm of a hand and manipulating the tube by bending it with a forefinger to touch the area being desoldered. Alternatively, the tube may be held like a pencil, with the housing laying outside the person's hand. When so used, a somewhat longer tube may be desirable.

In an alternative arrangement, the housing may be roughly spherical (i.e. a three dimensional circle) with a tube extending tangentially from the housing. In such a case, the desoldering wick may be coiled into what amounts to a three dimensional spiral or ball fitted loosely in the housing. The ball can rotate freely in the housing for dispensing wick. Such an embodiment may be used for containing longer lengths of desoldering wick, and particularly for narrow widths of wick.

FIGS. 7 and 8 illustrate another embodiment of desoldering wick dispenser for use with a conventional package of desoldering wick as described in the background portion, and similar to what is described and illustrated in U.S. Patent No. 3,430,886. FIG. 9 illustrates an injection- molded plastic attachment(most of which is also illustrated in FIG. 8) which snaps into the conventional package to make the desoldering wick dispenser combination. The conventional package 510 has a dish-shaped half 512 with a hollow central hub 514. A cover 516 is secured to the hub (or may form part of the hub) and fits closely near the outer edge of the disc-shaped half. A loose coil (not shown) of desoldering wick lies within this package around the hub. An end of the wick passes through the narrow gap between the dish-shaped half and the cover.

A molded plastic attachment 518 is connected to the package or housing containing the coil of desoldering wick. The attachment has a hollow "axle" which fits loosely through the hollow hub of the package of desoldering wick. A circumferential rib or interrupted rib 522 on the axle fits through the hub, which is slightly flexible material and inhibits removal of the attachment from the package. A flange 524 is adjacent the dish-shaped half of the package on its opposite face. The fit of the axle and space between the rib 522 and flange are loose enough that the package with desoldering wick can rotate freely.

The flange 524 at the axle is integral with a roughly J-shaped extension 526 which has a generally H-shaped cross-section with a web 528 and two flanges 530. There is a round nose 532 approximately perpendicular to the axle, at the opposite end of the extension from the axle. There is a passage 534 through the nose and a tube 536 of helically wound stainless steel wire is inserted into the end of the passage. The opposite end of the passage is near the largest diameter portion of the housing (package) containing the coil of desoldering wick when the attachment is snapped into the conventional package. The gap between the dish-shaped half and cover is also near this largest diameter portion of the housing.

An end of the wick from the outside of the coil of wick in the housing passes through the gap between the dish-shaped half and cover, through the passage 534 and through the helically wound tube 536. A small portion of the end of the wick 538 extends beyond the end of the tube. In the illustration of FIG. 7, a small amount of the wick 538 can be seen between the cover 516 and ending of the passage of through the nose.

Such an assembly of a conventional package serving as a housing for desoldering wick and the attachment 518 can be used in the same manner as the preceding embodiments. When the desoldering wick is drawn through the tube for use, the coil of wick in the housing may rotate relative to the hub, or the entire package may rotate as the wick is drawn through the gap at the edge of the cover.

Instead of extending radially from the housing as illustrated in the embodiment of FIGS. 7 to 9, an attachment may be made with the nose extending generally tangentially from the circular package. In an embodiment where the tube extends tangentially from the housing, the direction should have the same handedness as the coil of desoldering wick to minimize the chance of binding as the wick is pulled from the coil.

Instead of an attachment as illustrated in FIGS. 7 to 9, an all-wire attachment maybe used. In such an embodiment, the wire used to form the helically wound tube is extended and wrapped in a second coil to form an axle to fit through the hub of a conventional package for desoldering wick. Some additional stiffening may be provided between the end of the tube and the wire- wound axle through the package.

Claims

CLAIMS:

1. A desoldering wick dispenser comprising: a housing; and a coil of desoldering wick in the housing, and characterized by: a tube connected to the housing; and an end portion of the wick extending from the coil through the tube to protrude beyond the end of the tube.

2. A desoldering wick dispenser according to claim 1 wherein the tube comprises a helically wound wire extending away from the housing, and preferably wherein a major portion of the helically wound wire has coils substantially touching and a minor end portion of the wire has coils spaced apart from each other.

3. A desoldering wick dispenser according to either one of claims 1 or 2 wherein the housing comprises: a body having an end face tapering outwardly nearer the center of the housing; and a central aperture in the tapering end face; and wherein the tube extends away from the aperture and the end portion of the coil extends from the inside of the coil.

4. A desoldering wick dispenser according to any one of the preceding claims wherein the end face of the housing is generally conical with an included half angle in the range of from

45 ° to 75 °.

5. A desoldering wick dispenser according to either one of claims 1 or 2 wherein the housing is generally circular and the tube extends away from an edge portion of the housing in a tangential direction.

6. A desoldering wick dispenser according to either one of claims 1 or 2 wherein the housing is generally circular and the tube extends away from an edge portion of the housing in a radial direction.

7. A desoldering wick dispenser according to either one of claims 1 or 2 wherein the tube is on an attachment comiected to the housing so that the housing can rotate relative to the housing.

8. A desoldering wick dispenser according to any one of the preceding claims further comprising a cover on a face of the housing, the cover conforming approximately to the shape of the coil of wick.

9. A desoldering wick dispenser according to any one of the preceding claims wherein the tube is made of a metal that is not wettable by molten solder and preferably the metal comprises stainless steel.

10. A desoldering wick dispenser according to either one of claims 1 or 2 wherein the housing comprises an outwardly tapering end face with the tube extending from the center of the end face.

11. A desoldering wick dispenser according to any one of the preceding claims wherein the coil is either in the form of a spiral with the end portion extending from an inside part of the spiral, or comprises multiple layers, each layer being in the form of a helix of wick with the end portion extending from an inside part of a helix.

12. A desoldering wick dispenser according to any one of the preceding claims wherein the coil comprises a spiral having a shape approximately complementary to an end face of the housing.

13. A desoldering wick dispenser according to any one of the preceding claims wherein the tube is connected to the housing by the desoldering wick extending through the tube.