MXPA99007320A - Soldering iron tip and method of making the same - Google Patents

Abstract

A technique for producing soldering iron tips entails cutting clad wire into a plurality of segments, each segment comprising a core of material (such as copper) and an outer protective layer (such as stainless steel, Ni, Cr, or alloy thereof). Each clad wire segment is then shaped into a soldering iron tip by a cold or hot heading process, or other metal forming process. In the finished tip, the protective outer layer is disposed behind the working area of the tip, and serves to reduce the corrosion of the tip, and to improve the electrical conductivity between the tip and the soldering iron handle. A heater element can be formed at one end of the soldering iron tip from the same clad wire segment used to produce the tip itself, thereby ensuring good thermal transfer properties between the heater element and the tip. The invention also pertains to a technique for forming a protective outer layer on the working area of the tip. The technique comprises stamping caps from a thin strip or sheet of protective material, such as iron. More specifically, the caps are stamped out of the sheet using a die having a shape which resembles the shape of the working area of the soldering tip. The caps formed in this manner are then inserted over the ends of the tips, and attached thereto by applying brazing material to the formed cap or to the strip of material prior to forming the cap.

Description

CAUTIN POINT AND MANUFACTURING METHOD OF THE SAME BACKGROUND OF THE INVENTION The present invention is concerned with techniques for making soldering tips having protective outer layers and with the tips produced therefrom. Manufacturers of soldering irons (also as soldering irons) commonly use copper (Cu) or copper-based materials for the tip of the soldering iron. Copper offers high thermal conductivity at a relatively low cost. In addition, copper can be easily machined to the desired tip geometry. For example, Figure 1 illustrates an exemplary tip 1 formed by machining a monolithic copper rod or a copper alloy 2. However, copper tips also have a variety of undesirable properties. When heated to the high temperatures required for welding, the tips can dissolve in the weld and / or corrode in the air. In addition, the tips can be deformed when mechanical pressure is applied to them. For this reason, simple copper-based solder tips have a relatively low tip life. The prior art has addressed this problem by coating the copper tips with one or more outer layers. More specifically, as illustrated in Figure 2, the end of the tapered portion of the tip 1 (commonly referred to as the "work area") is coated with an outer layer 4 of iron (Fe). 4 protects the softer copper center 2 from deformation during welding operations and prevents it from dissolving in the weld.The iron is also easily wettable by the molten solder.The rest of the weld iron tip 1 is covered by other types of materials 6 such as a layer of chromium (Cr) or a layer of chromium formed on a layer of nickel (Ni) These layers 6 provide a good electrical connection between the tip of the soldering iron and ground, to ensure a low resistance and low tip potential to ground These layers 6 also protect the copper layer 2 from corrosion in air.Chrome also offers poor wettability by welding and thus prevents welding ura run to the tip from the work area and degrade the performance of the soldering tip. Normally, these materials are coated on the copper tip by a deposition technique known as electroplating without electrodes or electrolytic coating. Electroplating involves the application of a voltage between the tip of the soldering iron (cathode) and pieces of the metal to be deposited (the anode), through an aqueous acid-based electrolyte. The soldering iron tip and the metal anode are both immersed in the electrolyte. The applied voltage causes the metal ions to flow from the anode to the cathode (soldering iron tip) through the electrolyte, thus depositing the metal on the tip of the soldering iron in a controlled manner. For example, U.S. Patent No. 3,315,350 proposes a technique for the electrolytic coating or plating (or electrodeposition) of an iron layer on a copper tip and then the electrolytic coating of an additional layer of nickel and chromium on the iron layer. . U.S. Patent No. 3,986,653 proposes the electrolytic coating of an outer layer of osmium or ruthenium (or an alloy thereof) on a soldering iron tip. Electroplating (electroplating or veneering) of copper soldering tips has disadvantages. First of all, the electrolytic coating sometimes produces a coating of unequal thickness on the tip, especially in regions where the contour of the tip changes abruptly. Secondly, the process itself is inherently unstable, to result in differences in the thickness and quality of the electrolytic coating from one production batch to the next. Third, the electrolytic coating is relatively expensive, which is partly due to the large amount of manual labor required by the technique and the need to dispose of the chemical solutions used in the process in an environmentally safe manner.

For these reasons, some manufacturers have considered alternative ways to build tips that have hardened outer layers. For example, US Patent No. 4,055,744 describes a technique for forming a hardened outer layer on the working area of a soldering iron tip by separately forming an iron cap and then mechanically grinding the cap onto the soldering iron tip. The composite structure of the cap and the tip is further formed by manual hammering of the composite structure or by using a tipping machine. While the problems associated with the electrolytic coating are avoided, the tipping of the cap to the copper tip can strongly stick the cap to the tip only at selective points of the tip, such as at the base of the tip, to reduce by this the contact area between the tip and the lid. This in turn can reduce the transfer of heat from the tip to the lid, thus reducing the performance or efficiency of the soldering iron. Another problem addressed by the present invention is concerned with soldering irons that include heating elements. "As illustrated in Figures 3 and 4, a heating element 8 is the component of the soldering iron that actually generates heat. electric coils of the soldering iron (not shown) transfer energy to the heating element 8, which in turn transfers heat to the working area of the soldering tip 1. In a tip design produced by the assignee of the present invention, the heating 8 comprises a coated wire segment having an inner core 12 and an outer layer 10 formed thereon The heating element 8 is press fit into a machined hole 14 located in the rear part of the tip 1. The mechanical interface 16 (in FIG. 4) between the heating element 8 and the tip 1 prevents heat transfer from the heating element 8 to the tip 1. Accordingly it is an exemplary objective of the present invention to provide a technique for making soldering tips that facilitates the efficient and reliable large-scale production of the tips, preferably without the use of electroplating or plating (plating). It is a further object of the present invention to provide a technique for making soldering tips that do not impose interfaces that prevent the flow of heat from the heating element to the tip.

BRIEF DESCRIPTION OF THE INVENTION These and other exemplary advantageous features are obtained according to a first aspect of the invention which encompasses the production of a tip from a coated wire segment. The technique comprises cutting a length of coated wire into a plurality of segments, wherein each segment comprises a core of material (such as copper) and an outer protective layer (such as stainless steel, high purity nickel, high purity chrome). , Fe-Ni alloys such as Invar-type alloys or other suitable material). Then each coated wire segment is formed in a soldering iron tip by a cold-pressing process or another metal-forming process. At the finished tip, the outer protective layer is disposed "behind" the working area of the tip and provides good electrical conductivity between the tip and ground, in order to maintain a low resistance and voltage potential from tip to ground. The outer layer also protects the inner (copper) core from oxidation and offers poor wettability, which prevents the weld from adhering to it. According to another aspect of the invention, the coated wire segment can be further formed to form an integrated heating element located at one end of the tip. Since the heating element is formed from the same segment of the coated wire segment as the tip itself, this technique ensures metallurgical continuity between the heating element and the working area of the tip and by this improves the heat transfer between the heating element and the tip when eliminating the mechanical interface 16 shown in figure 4. According to another aspect of the invention, the metal forming steps described above can be carried out on a wire segment (or rod) that does not include an outer protective layer. According to yet another aspect of the invention, an outer protective layer for the working area of the soldering iron tip can be formed by inserting a cap formed separately from iron (or similar material) over the portion of the working area of the tip . More specifically, the technique comprises the production of a strip or thin sheet of protective layer material such as iron. Then tapered caps are stamped from the sheet by using a die that has a shape that resembles the shape of the tip of the soldering iron. Then the lids formed in this way are inserted over the working area of the tips of the soldering iron and joined thereto by applying a welding material to the lids or the tips and then melting or sintering the welding material. Alternatively, the welding material can be applied directly to the strip of material (before the stamping is carried out) to further make the manufacturing process faster. Whether in one event or another, the use of welding or a similar technique improves the thermal conductivity between the tip and the cap by creating an intimate metallurgical bond between the tip and the cap compared to the previous technique of tipping the cap to the cap. tip. In accordance with another aspect of the present invention a wire or coated rod segment is used to form a soldering iron tip that includes one or more outer protective layers over the working area of the soldering iron tip.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of the present invention will be more readily understood upon reading the following detailed description in conjunction with the drawings in which: Figure 1 shows a soldering iron tip machined from according to the prior art; Figure 2 shows a soldering iron tip machined with layers of material deposited thereon by means of the use of electroplating or electroplating, according to the prior art; Figure 3 shows a machined soldering tip that includes a machined hole in its back to receive a heating element according to the prior art; Figure 4 shows a soldering iron tip machined with a heating element pressurized to a machined hole in the back of the tip according to the prior art; Figures 5-8 show the transformation of a coated wire segment to a soldering tip having an outer protective coating according to a first embodiment of the present invention; Figure 9 shows an exemplary technique for forming the coated wire segment; Figure 10 shows an exemplary technique for making a soldering iron lid according to a second embodiment of the invention; Figure 11 shows an exemplary perspective view of the soldering cap produced by the technique shown in Figure 10; Figure 12 shows an exemplary way to attach the lid to the soldering iron tip; Figures 13-14 show the transformation of a coated wire segment to a soldering iron tip having an external protective coating in its working area according to another embodiment of the present invention and Figures 15-17 show the transformation of a a coated wire segment having at least two outer layers to a soldering tip having an outer multilayer coating according to yet another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION In the following description, for purposes of explanation and not limitation, specific details are summarized in order to provide a complete understanding of the invention. However, it will be apparent to one skilled in the art that the present invention can be practiced in other embodiments that deviate from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as not to obscure the description of the present invention with unnecessary detail. In addition, for purposes of brevity, the following description is framed in the context of soldering irons. However, the principles described herein are equally applicable to solders for desoldering. Desoldering soldering irons heat and remove the previously applied solder. 1. Formation of a soldering iron tip using a coated wire or rod segment A first exemplary embodiment produces the soldering iron tips (or soldering tips for desoldering) from coated wire or a coated rod. As shown in Figure 5 in a cross-sectional view, a segment 20 of coated wire (or rod) comprises a core or core of material 24, over which another electrically conductive protective layer 22 is metallurgically bonded. The material 24 of the core may comprise a metal such as copper of high purity, such as copper alloy Nos. C10100 or C10200 having copper contents of 99.99% copper and 99.95% copper respectively. To provide the machinability of copper, copper alloy containing tellurium, such as copper alloy No. C14500 (consisting of 99.5% copper, 0.5% Te, and 0.008% P) can be used. The protective layer 22 may comprise, but is not limited to, high purity nickel, high purity chromium or any alloy thereof, such as Fe-Ni (for example Invar type alloys), Fe-Ni-Cr or other suitable material. The layer 22 may also comprise stainless steel. In accordance with an exemplary embodiment, coated wire produced by Anomet Products, Inc. of Shrewsbury, Mass., Can be used to produce soldering tips in accordance with the techniques described herein. A semi-finished tip produced by the coated wire segment 20 is shown in Figure 6 (in cross-sectional view), while a finished tip produced by the coated wire segment 20 is shown in Figure 7 (in sectional view). transversal). With reference to Figure 7, the tip has a cylindrical portion 23 attached to a cylindrical portion 21 of smaller diameter. The portion 21 ends in a tapered working area 28. The outer layer 22 of the coated wire covers the underlying copper core or core 24, except for the working area 28 of the tip. At the finished soldering tip, the outer protective layer 22 serves a variety of purposes. First, layer 22 protects the underlying copper core 24 from corrosion in the air. Second, outer layer 22 provides good electrical contact between the tip and ground which in turn prevents a voltage from accumulating between the tip and ground that could be discharged during welding operations and damage the components to which it is subjected. applies the welding. In the case of welding of electrical components, military specifications require a peak to ground voltage potential of no more than 2 millivolts (mv) and a tip-to-ground resistance of no more than 2 ohms. Third, the outer layer 22 offers relatively poor wettability by welding and thereby prevents the weld from advancing beyond the working area of the soldering tip. In general, the use of coated wire or rod as a starting material eliminates the need to form the outer protective layer 22 by electroplating or electroplating at a later stage in the production of the tip and therefore eliminates the disadvantages described above of electroplating. or electrolytic coating. 2. Formation of an integrated heating element Another aspect of the invention involves the formation of a heating element that is integral with the tip of the soldering iron. For example, as shown in FIG. 8, the finished tip (or semi-finished tip) with an integral heating element includes a cylindrical portion 23 sandwiched between the cylindrical portion 21 and a heating element 26 (as shown in FIG. cross section) . The heating element 26 and the tip itself are formed from the same segment 20 of coated wire (or rod). As such, there is metallurgical continuity between the heating element 26 and the tip, which facilitates the transfer of thermal energy from the heating element 26 to the tip. The outer layer 22 of the coated wire covers the tip, in which the heating element 26 is included, but does not cover the tapered end portion 28 of the tip. As mentioned above, the protective layer 22 may comprise, but is not limited to, stainless steel, high purity nickel, high purity chromium or some alloy thereof, such as Fe-Ni (eg, Invar-type alloys), Fe-Ni-Cr or other appropriate material. More specifically, Invar-type alloys of different compositions can be selected to provide different soldering power load capacities. For example, progressively higher power loads can be supplied by layers of: (1) 42% Ni, 6% Cr, 52% Fe; (2) 42% Ni, 58% Fe; (3) 44% Ni, 56% Fe; and (4) 52% Ni, 48% Fe. 3. Making a soldering iron tip using metal forming Those skilled in the art will appreciate that there are many techniques for transforming the coated wire (or rod) segment 20 shown in Figure 5 to a desired tip geometry (such as the shapes of points shown in Figures 6, 7 or 8) in which machining of wire or rod segment 20 is included in the desired shape. Alternatively, according to the present invention, a metal forming process such as hot or cold upsetting can be used to manufacture the tip. Figure 9 illustrates an exemplary technique that employs a cold upset process to transform a wire segment to a finished or semi-finished tip. The exemplary technique begins by feeding a length of wire coated from a wire spool to a cutting element (step SI), which cuts a segment of the wire of prescribed length (step S2). Following the cutting operation, the segment is then transported to a first die chamber (step S3), wherein one or more dies provide one or more blows to taper one end of the segment (step S4) to form a portion 21 that it has a reduced diameter, as shown in figure 6, which is then processed to form a tapered working area 28, as shown in figure 7. The cold upset per se is well understood in the art and thus the details of such a process will be evident to those experienced in this technique. By way of example, U.S. Patent Nos. 3,669,334, 3,934,293, 4,058,865 and 5,146,668 provide exemplary details of typical cold-pressing machinery and techniques for forming wire segments. These patents are incorporated by reference herein. The process may omit steps S5 and S6, after which the part is supplied in step S7. At this stage in the manufacture of the tip, the protective layer 22 can be removed from the work area 28 of the tip by machining or a similar technique. A protective layer can be added to the work area 28 at some later stage of production by using any suitable technique, such as by using electroplating (electrolytic coating or plating) or by adjusting a lid on work area 28 (to be discussed later). at the moment) . If an integral heating element is desired, the tip shown in Figure 7 can be transported to a second die chamber (step S5), wherein another die provides one or more blows to form the heating element 26 at one end of the tip (step S6), as is shown in Figure 8, to thereby produce the finished tip with an integrated heating element 26. The finished tip is supplied in step S7. Steps S5 and S6 are enclosed in a box of broken lines to illustrate that they can be omitted to produce a tip without an integrated heating element, if desired. Alternative methods for constructing the tip include the use of a hot-upsetting process (instead of a cold-upsetting process) or formation of the heating element 26 before forming the portions 21, 28 or forming the heating element 26 to same time as the portions 21, 28 (for example, by means of the simultaneous application of several blows of several dies). The exemplary steps shown in Figure 9 may be fully automated or may require the manipulation of parts and / or machinery by a human operator. In addition, the tip portions (for example portions 21, 23) can be formed in such a way that they have any desired geometry.

The process discussed above forms the coated wire segment 20 shown in Figure 5. However, the technique can also be used to form wire segments that do not have an outer protective layer 22. In this embodiment, the protective layer 22 could be formed subsequently on the tips formed by means of electroplating (or electrolytic coating) or a similar technique. 4. Formation of an outer layer cap on the tip working area Figures 10-12 illustrate another aspect of the present invention for forming a hardened outer layer on the tip working area. The technique shown in Figures 10 to 12 has wide application for many types of tips produced by various techniques. For example, the technique shown in Figures 10 to 12 can be used to supply a hardened outer layer on the exposed end 28 of the soldering iron tip produced by the method described with reference to Figures 5 to 9 or it can be used to supply a hardened outer layer for machined copper centers or cores, such as the machined core 2 shown in Figure 1. As shown in Figure 10, a continuous thin strip of material 30 is produced (e.g., a strip having a thickness about 0.127 mm (5 mils)). According to exemplary embodiments, the material can comprise high purity iron (for example iron having a purity of 99.5% in an exemplary embodiment), nickel or other material or alloy. After this, a plurality of lids 34 are stamped out using the die 32 which engages with the die 35. Only a couple of dies (32, 35) have been shown to facilitate discussion, although several pairs of dies can be shown. (32, 35). The die 32 has an external contour 37 that defines the internal contour of the cover 34, while the die 35 has a recess or recess having a contour 39 that defines the external geometric shape of the cover 34. Figure 11 shows a cover Exemplary formed 34 having a tapered end 38 and a cylindrical portion 36. The cap 34 may alternatively be formed by other techniques such as, but not limited to, an intense drawing process. Then the lid 34 is inserted over the working area 33 of a tip 41 in the manner shown in Figure 12. The lid 34 is preferably secured to the tip 41 by a metallurgical gluing technique such as welding or a similar technique. For example, a small amount (for example approximately 0.0051 mm (0.2 mils)) of high purity silver or "CUSIL" (72% Ag, 28% Cu) can be applied to a mating surface of either the stamped cover 34 or the tip 41 and then fused or sintered to metallurgically attach the lid to the tip. Alternatively, to further promote production efficiency, the welding material can be applied to the strip of material 30 prior to stamping. During fusion, silver and copper form a eutectic CuAg that attaches the cap to the tip. As an alternative to stamping the lid 34 from a sheet of material such as iron, the lid can be produced by cold upsetting or forming wire segments or metal shapes (eg spheres) to the desired tapered shape. The details of such a process will be evident to those with experience in the art and thus will not be discussed in further detail. By way of example, US Pat. No. 3,669,334 describes one such technique. The finished soldering tip 41 shown in cross-sectional view in FIG. 12 comprises a center or copper core 40 having a tapering working area end 33. The cover 34 is inserted on the end 33 of the work area. The cover 34 can be brought into contact with another layer 42 (or series of layers). These additional layers 42 can be formed by any suitable technique. For example, these layers 42 can be formed by the technique shown in Figures 5-9 or via electroplating or electroplating. Alternatively, these layers 42 may themselves be separately formed as caps and inserted onto the core 40 prior to the insertion of the lid 34, such that the tip has a plurality of overlapping covers. In any case, these layers 42 preferably have a low wettability by welding and provide a low tip-to-ground potential as previously described. Finally, while the tip 41 shown in Figure 12 does not include an integrated heating element, this technique can be used to provide tips 34 for tips that include integrated heating elements (such as the tip shown in Figure 8). According to the exemplary embodiment shown in FIG. 12, the external contour of the working area 33 generally coincides with the internal contour of the lid 34. Alternatively, the terminal end of the tip does not need to coincide with the internal contour of the lid 34. For example, the terminal end of the tip can be truncated along the line 61, to thereby form an intermediate region between the end of the tip and the lid 34. This intermediate region is filled with a solder composition (or another metallic substance) to improve the thermal conductivity between the tip and the lid 34.

More specifically, in one embodiment, a quantity of welding material is added to the interior 63 of the lid 34 before adjusting the lid 34 on the end of the tip. The welding material can be applied to the inside of the lid in the form of a paste, in solid or powder form or some other form. Once applied, the lid 34 (with welding material deposited thereon) is heated to melt or sinter the welding material, to thereby bond the welding material to the interior of the lid at its distal end. After the lid 34 is cooled, the lid is inserted over the end of the tip and is joined thereto by an appropriate technique such as welding or sintering. In yet another embodiment, the lid 34 can be secured to the end of the tip before the solder material cools, such that the solder material is still in a molten or at least still soft form. This technique also ensures that the junction between the end of the tip and the lid does not contain any air space. Still other forms of the invention comprise securing the cap 34 to the tip end and then adding the solder material to the inner cavity between the cap 34 and the tip through a hole in the cap (not shown) for example.

. Formation of the outer layer on the work area when using coated wire Another exemplary embodiment involves the production of soldering tips (or soldering tips for desoldering) that have an outer layer on the tip work area from a segment of coated wire or a segment of coated rod. As shown in Figure 13 in cross-sectional view, in this embodiment the coated wire (or rod) segment comprises a core or center of material 70 made of copper or a copper alloy. The protective layer 71 may comprise, but is not limited to, high purity iron, nickel or similar material or alloy. This segment can be configured or formed according to any of the techniques discussed above to a desired tip geometry, such as the exemplary tip geometry shown in Figure 14 in cross-sectional view. As shown in Figure 14, the tip includes a copper core 70 having an outer layer 71 (for example consisting of iron) that substantially covers the entire surface of the tip, in which the area of the tip is included. work 72. The outer layer 71 may be joined at the distal end of the work area 72 by any suitable technique, such as gripping the far end of the work area 72. Furthermore, although not shown, additional layers may be formed on the outer layer 71, such as a layer having the properties discussed above in the context of Figure 5 (in which but not limited to high purity nickel, high purity chromium or some alloy thereof, such as Fe-Ni or other alloys type Invar, Fe-Ni-Cr, stainless steels or other appropriate material). These additional layers can be formed on the outer layer 71 by any suitable technique such as electroplating or electroplating. Instead of the electrolytic coating (or electroplating or plating) of additional layers on the layer 71, still another embodiment of the present invention comprises forming a tip having two or more outer layers when forming or forming a coated wire segment having two or more outer layers. or more external layers, as shown in Figure 15 in cross-sectional view. More specifically, the segment (or rod) of coated wire shown in Figure 15 comprises a center or core of material 80 made of a metal such as copper or a copper alloy. A first coated layer 82 comprises, but is not limited to, high purity iron, nickel or a similar material or alloy. A second outer covering layer 84 may comprise, but is not limited to, high purity nickel, high purity chromium or any alloy thereof, such as Fe-Ni or other Invar type alloys, Fe-Ni-Cr, stainless steels or other suitable material. This segment can be configured or formed according to any of the techniques discussed above to a desired tip geometry, such as the exemplary tip geometry shown in Figure 16. As shown in Figure 16 in cross-sectional view, the The tip includes the core or copper center 80 having outer layers 82 and 84 that cover substantially the entire surface of the tip, in which the work area 86 is included. The outer layer 84 can be separated or removed to reveal the layer external 82 (formed, for example, of iron) in the work area 86, as shown in FIG. 17 in cross-sectional view. The outer layer 84 can be removed by any suitable technique such as machining. The exemplary embodiments described above are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus, the present invention has the possibility of variations in the detailed implementation that can be derived from the description contained herein by one skilled in the art. It is considered that all such variations and modifications are in the scope and spirit of the present invention as defined by the following claims.

Claims (57)

1. CLAIMS 1. A process for making a soldering tip having an external protective layer, characterized in that it comprises the steps of: cutting a length of coated wire to form a coated wire segment, the wire includes a core material surrounded by a layer external protective that is metallurgically bonded to the core material; and deforming the coated wire segment to form a working end, thereby forming the soldering iron tip of the outer protective layer. The process according to claim 1, characterized in that it further includes the step of forming the coated wire segment to form a heating element at an end opposite the working end. 3. The process according to claim 1, characterized in that the forming step comprises cold or hot upsetting. 4. The process according to claim 2, characterized in that the forming steps comprise cold or hot upsetting. 5. The process according to claim 1, characterized in that the core material comprises copper or a copper alloy. 6. The process according to claim 1, characterized in that the protective outer layer is located behind a working area of the soldering iron tip and provides a low resistance or tip potential to ground and protects the soldering tip from corrosion in the air or dissolution by welding. The process according to claim 1, characterized in that the protective outer layer consists essentially of stainless steel, nickel, chromium, a nickel alloy, an iron-nickel alloy or a chromium alloy. The process according to claim 6, characterized in that the protective outer layer consists essentially of stainless steel, nickel, chromium, a nickel alloy, an iron-nickel alloy or a chromium alloy. 9. The process according to claim 1, characterized in that the protective outer layer is located at least on a working area of the soldering iron tip. 10. The process according to claim 1, characterized in that the outer protective layer consists essentially of iron or an iron alloy. 11. The process according to claim 9, characterized in that the outer protective layer consists essentially of iron or an iron alloy. The process according to claim 1, characterized in that the outer protective layer on the coated wire segment comprises at least a first outer layer and a second outer layer. The process according to claim 12, characterized in that, in a finished or semi-finished soldering tip, the first outer layer is located on a working area of the soldering iron tip and the second outer layer is located behind the soldering iron area. work of the soldering iron tip, where in addition the second external layer provides a low resistance or tip potential to ground and protects the soldering tip from corrosion in the air or solder dissolution. The process according to claim 2, characterized in that it also comprises the formation of a cylindrical middle section positioned between the heating element and the working end. 15. The process according to claim 14, characterized in that the cylindrical middle section has a first diameter and the heating element has a second diameter, wherein the first diameter is greater than the second diameter. 16. A soldering tip characterized in that it is produced by the process according to claim 1. 17. A soldering tip characterized in that it is produced by a process according to claim 2. 18. A soldering tip characterized in that it is produced by the process according to claim 12. 19. A process for manufacturing a soldering iron tip, characterized in that it comprises the steps of: cutting a length of wire to form a wire segment; forming the wire segment to form a working end by using a metal forming process, to thereby form the soldering tip and deforming the wire segment to form a heating element component at an end opposite the working end . 20. A process in accordance with the claim 19, characterized in that it also includes the step of forming a protective layer on the soldering tip after the forming steps. 21. The process according to claim 20, characterized in that the protective layer consists of essentially of stainless steel, nickel, chrome, a nickel alloy, an iron-nickel alloy or a chromium alloy. 22. The process according to claim 19, characterized in that the forming steps comprise cold or hot upsetting. 23. The process according to claim 19, characterized in that the wire segment is formed from copper or a copper alloy. 24. A soldering iron tip characterized in that it is produced by the process according to claim 19. 25. A soldering iron tip characterized in that it is produced by the process according to claim 20. 26. A soldering iron tip characterized in that it comprises: a metal core or core element made of a material having a high thermal conductivity, the core element or metal core has a first tapered working end and a second end opposite the first end, to form a heating element and an outer protective layer, metallurgically bonded to portions of the metal core element including the heating element, the heating element and the first tapered working end of the metal core element are arranged to promote the thermal transfer of energy between the heating element and the first tapered working end of the core element of metal 27. The soldering iron tip according to claim 26, characterized in that the outer protective layer is located behind a working area of the soldering iron tip and provides a low resistance or potential to ground and protects the soldering iron tip. of corrosion in air or dissolution by welding. 28. The soldering iron tip according to claim 26, characterized in that the external protective layer consists essentially of stainless steel, nickel, chromium, a nickel alloy, an iron-nickel alloy or a chromium alloy. 29. The soldering iron tip according to claim 27, characterized in that the outer protective layer consists essentially of stainless steel, nickel, chromium, a nickel alloy, an iron-nickel alloy or a chromium alloy. 30. The soldering iron tip according to claim 26, characterized in that the outer protective layer is arranged on the heating element but not on the first tapered working end. 31. The soldering iron tip according to claim 26, characterized in that the protective outer layer is arranged on at least the working end. 32. The soldering iron tip according to claim 26, characterized in that the outer protective layer consists essentially of iron or an iron alloy. 33. The process according to claim 31, characterized in that the outer protective layer consists essentially of iron or an iron alloy. 34. A process for applying a protective cap on a soldering iron tip, characterized in that it comprises the steps of: forming a lid from a sheet of metallic material, the lid having an internal contour that generally coincides with an external contour of a soldering iron tip; Fit the cap on the soldering iron tip and secure the cap to the soldering iron tip by metallurgically attaching the cap to the soldering iron tip. 35. The process according to claim 34, characterized in that it further comprises the step of applying a welding composition to the lid immediately following the adjustment step, wherein the step of metallurgically gluing comprises melting or sintering the welding composition. 36. The process according to claim 34, characterized in that it further comprises a step of applying a welding composition to the sheet of material before the forming step, wherein the step of metallurgically gluing comprises melting or sintering the welding composition. 37. The process according to claim 34, characterized in that the sheet of metallic material comprises iron or an iron alloy. 38. The process in accordance with the claim 34, characterized in that the tip includes a core or center formed from copper or a copper alloy. 39. The process according to claim 34, characterized in that the forming step forms a portion of the tapered end and a cylindrical portion on the lid. 40. The process according to claim 34, characterized in that the forming step comprises the intense stamping or stretching of a plurality of lids from the sheet of metallic material. 41. A process for manufacturing a soldering iron tip having outer protective layers, characterized in that it comprises the steps of: cutting a length of coated wire to form a coated wire segment, the wire includes a core material surrounded by a first protective layer external; configuring the coated wire segment to form a tapered end of the soldering iron tip; forming a layer from a sheet of a second protective material; adjust the cover on the tapered end of the soldering iron tip; and secure the cover to the soldering iron tip by metallurgically attaching the cap to the soldering iron tip. 42. A process for applying a protective cap on a soldering iron tip, characterized in that it comprises the steps of: forming a lid from a sheet of metallic material; adjust the cap on one end of the soldering iron tip; and secure the cover to the soldering iron tip by metallurgically attaching the cap to the soldering iron tip. 43. The process in accordance with the claim 42, characterized in that it further comprises the step of applying a welding composition to the lid immediately following the adjustment step, wherein the step of metallurgically gluing comprises melting or sintering the welding composition. 44. The process according to claim 42, characterized in that it further comprises the step of applying a welding composition to the sheet of material before the forming step, wherein the step of metallurgically gluing comprises melting or sintering the welding composition. 45. The process according to claim 42, characterized in that the sheet of metallic material consists of iron or an iron alloy. 46. The process in accordance with the claim 42, characterized in that the tip includes a core or center formed from copper or a copper alloy. 47. The process according to claim 42, characterized in that the forming step forms a portion of the tapered end and a cylindrical portion on the lid. 48. The process according to claim 42, characterized in that the forming step comprises the intense stamping or stretching of a plurality of lids from the sheet of metallic material. 49. The process according to claim 42, characterized in that it also includes the steps of: before the adjustment step, apply a welding composition to the inside of the lid to fill at least a portion of an interior cavity of the lid and heating the solder composition. 50. The process according to claim 49, characterized in that the solder composition is applied in the form of a paste. 51. The process in accordance with the claim 49, characterized in that the welding composition is applied in the form of a powder. 52. The process according to claim 49, characterized in that the welding composition is applied in the form of a solid. 53. A soldering iron tip, characterized in that it comprises: a core element or metal center made of a material having a high thermal conductivity; a protective cap secured to one end of the metal core or core element, wherein the cap and the metal core element define at least one intermediate region between the cap and the core element or metal core; a solder composition that fills the at least one intermediate region. 54. The process according to claim 1, characterized in that it also includes the steps of: forming a lid from a sheet of metal material, the lid has an internal contour that generally coincides with an external contour of the working end; adjust the lid on the working end; and securing the cap to the soldering iron tip by metallurgically attaching the cap to the working end. 55. The process according to claim 54, characterized in that it further comprises the step of applying a solder composition to the lid following the adjustment step, wherein the step of metallurgically gluing comprises melting or sintering the solder composition. 56. The process according to claim 54, characterized in that it further comprises the step of applying a welding composition to the sheet of material before the forming step, wherein the step of metallurgically gluing comprises melting or sintering the welding composition. . 57. The process according to claim 54, characterized in that it also includes the steps of: before the adjustment step, apply a welding composition to the inside of the lid to fill at least a portion of an interior cavity of the lid and heating the solder composition. SUMMARY OF THE INVENTION A technique for producing soldering tips comprising cutting coated wire into a plurality of segments is described, each segment comprising a core of material (such as copper) and an outer protective layer (such as stainless steel, Ni, Cr). or alloy thereof). Each coated wire segment is then formed into a soldering iron tip by a hot or cold upsetting process or other metal forming process. At the finished tip, the outer protective layer is disposed behind the working area of the tip and serves to reduce tip corrosion and to improve electrical conductivity between the tip and handle of the soldering iron. A heating element can be formed at one end of the tip of the soldering iron from the same segment of coated wire used to produce the tip itself, thereby ensuring good thermal transparency properties between the heating element and the tip. The invention is also concerned with a technique for forming an outer protective layer over the working area of the tip. The technique comprises stamping lids from a thin strip or sheet of protective material, such as iron. More specifically, the covers are stamped from the sheet by using a die having a shape that resembles the shape of the working area of the soldering tip. The lids formed in this manner are then inserted or fitted over the ends of the tips and joined thereto by applying welding material to the formed cap or to the strip of material before the cap is formed.