WO1992000827A1

WO1992000827A1 - Forming a solder connection

Info

Publication number: WO1992000827A1
Application number: PCT/GB1991/001130
Authority: WO
Inventors: David William Evans
Original assignee: Pmc (Sheffield) Ltd.
Priority date: 1990-07-10
Filing date: 1991-07-10
Publication date: 1992-01-23
Also published as: GB9015146D0

Abstract

A solder connection is formed to a first component (1) formed from a non-solderable material (such as aluminium) by encapsulating partially a second component (3) formed from a solderable material (such as copper) in the first component. A third component (7) is connected to the first component by means of a solder connection to the second component.

Description

FORMING A SOLDER CONNECTION

The present invention relates to the formation of a solder connection to a component whose outer surface is provided by a non-solderable material. The invention provides a method of making such a connection, and an article which comprises such a component to which a connection has been made.

Connections to certain metallic materials cannot be made by means of solder bonds because those materials are non- solderable in some way. The materials may be inherently non-solderable, or they may have been treated in such a way that the formation of a bond is undesirable because it would lead to damage of the article formed from that material. For example, the formation of solder bonds to certain materials can be impractical because of undesirable reaction products between those materials and solders or fluxes or both which are used in the formation of such bonds. Examples of such materials include aluminium and certain steels, especially stainless steels. Other materials may be rendered non-solderable as a result of a surface finish which might be damaged as a result of a soldering operation. For example, a material may have applied to it a surface pattern, such as by screen printing, which might be damaged as a result of heat applied to the material during a soldering operation. An aluminium article which has been anodised to give it a desired appearance may also be damaged as a result of a soldering operation, not only as a result of a reaction between solder or flux or both and the aluminium but also as a result of the heat supplied to the article during the soldering operation which can affect adversely the appearance conferred by anodising.

The present invention provides a technique by which connections may be formed to a component whose outer surface is provided by a non-solderable material by means of a solder bond.

Accordingly, in one aspect, the invention provides an article comprising a first component formed from a metal whose surface is non-solderable, the first component being disposed around a second component whose surface is provided by a solderable material, so as to encapsulate the second component partially, and a third component which is connected to the first component by means of a solder bond between the second and the third components.

In another aspect, the invention provides a method of making a connection to a first component formed from a metal and whose surface is provided by a non-solderable material, the method comprising:

(a) deforming the first component around a second component whose surface is provided by a solderable material so as to encapsulate the second component at least partially; and

(b) connecting a third component to the first component by means of a solder bond between the second and third components.

The technique of the present invention has the significant advantage that, because the second component is at least partially encapsulated by the first component, it allows a solder connection to be made to the first component formed from a non-solderable material in such a way that the resulting article has the appearance of one in which a connection has been made directly between the first and third components. The invention therefore allows articles to be made from non-solderable materials whose appearance simulates closely the appearance of articles which are formed from solderable materials in which connections between components thereof are made directly by means of one or more solder bonds. This is possible because the second component can be virtually hidden from view by encapsulation thereof by the first component. For example, the invention allows articles to be made from aluminium (which can be considered to be non-solderable for the purposes of this invention because of the highly reactive nature of fluxes which are required to be used in order to make a solder bond), whose appearance simulates very closely that of similar articles formed from pewter. Pewter is an attractive material from which to form which can be articles because of the attractive appearance obtained by appropriate finishing, such as polishing to obtain a bright finish, brushing to obtain a dull finish, and hammering, milling, engraving, or knurling to obtain a textured finish. It is also possible to form solder bonds to connect components of pewter articles to one another. However, because of its softness, the manufacture of articles from pewter is highly craft sensitive, requiring much hand-working and skill, and the resulting articles are therefore undesirably expensive. The present invention allows similar articles to be formed from materials such as aluminium, which can be treated so that similar surface effects are obtained before other components are connected by means of solder bonds. In this way, articles such as, for example, tankards (where a handle is connected to a tubular vessel) can be formed from aluminium having an appearance which simulates closely that of a pewter tankard.

A further significant advantage of the present invention is that it allows a component of an article to be provided with a desired surface finish, for example by polishing, brushing, hammering, milling, engraving or knurling, before another component of the article is connected to it. The technique of the present invention makes it possible to form a connection to the finished component by means of a solder bond without impairing the finish which has been imparted to the component. In this way, the provision of a finish to a component of an article can be greatly facilitated since the surface to which the finish is applied is not interrupted or interfered with by another component of the article which has already been connected. - --

The non-solderable material which provides the outer surface of the first component may be non-solderable for any of a number of reasons. For example, the material may be one which requires the use of a highly reactive solder or a highly reactive flux or both in order to form a solder connection. Products of reactions between the material and the solder or the flux may be noxious making the process of forming the solder bond hazardous to or inconvenient for an operator. The non-solderable material may be non-wettable by solder. Alternatively, the non-solderable surface of the first component may be prone to damage as a result of a soldering operation. For example, the surface may have been finished in such a way that its appearance might be impaired as a result of a soldering operation. For example, the surface of the component may have been provided with a finish such as a polished finish which would be impaired as a result of a subsequent soldering operation. Alternatively or in addition, the surface of the component may have been provided with a pattern, for example by screen printing, or a coating, for example a polymeric coating such as one of a paint or of PTFE, which might be damaged as a result of a soldering operation.

The first component of the article will generally be provided, at least in the region of the connection to the third component, in the form of sheet material. Sheet material can readily be deformed so as to encapsulate partly a second component. Generally, the first component will be formed from a single material, although the non-solderable surface of the component may be provided by a different material. Frequently, the first component will be formed from a single material which is non-solderable, such as aluminium.

The second component of the article will generally be elongate so that it can be encapsulated partly along substantially its entire length. For example, the second component can be formed from a rod or wire. When the first component of the article is hollow, and the second component extends around at least part of the perimeter of the first component, the second component may be in the form of a ring or band: such a ring may be continuous or it may be split to facilitate positioning the ring around an article. The cross-section of the second component may be used to determine the configuration of the first component once it is disposed around the second component. For example, the first component, in the region in which it is disposed around the second component, may have a rounded cross-section as a result of use of a second component having a generally circular cross-section. The first component may be given a more angular shape by use of, for example, a second component with a square cross-section.

The second component may include a formation (for example a lug or boss) to which the solder connection to the third component can be made.

The third component may consist only of a solderable material. For example, it may be formed from a material such as copper, brass, pewter, and other tin or lead based alloys. Alternatively, the third component may be formed from more than one material of which one material is solderable and another material is non-solderable. For example, the third component may comprise a first sub-component formed from a metal whose surface is non-solderable, the first sub-component being disposed around a second sub-component whose surface is provided by a solderable material, so as to encapsulate the second sub-component partially. The present invention therefore makes it possible to form a connection between two components, each of which being formed from a metal whose outer surface is non-solderable, by means of a solder bond.

The use of aluminium for the first component of the article has significant advantages. On one hand, its finish or appearance can be arranged to simulate very closely the appearance or finish of pewter. For example, it can be polished to give a bright finish, or it can be made to appear dull, for example by appropriate brushing. It can also be provided with other surface finishes by appropriate treatment. However, other effects can be obtained through the use of aluminium, for example by anodising the surface of the aluminium. Anodising may be used to colour the surface of the aluminium, or to make it water or corrosion resistant. When anodising is used to change the colour of the material, particularly attractive effects can be obtained by engraving the surface of the material so that the engraving on the surface shows the natural colour of the aluminium against the background provided by the coloured surface.

A particularly significant advantage of the use of materials other than pewter is that certain mechanised sheet metal working techniques can be used which cannot be practised on pewter because of its softness. Thus articles may be formed from materials such as aluminium or stainless steel using techniques such as mechanised spinning, fluid forming, drawing and automated bending using rollers, for example to deform the first component so as to encapsulate partially the second component.

The article provided by the technique of the present invention may take a number of forms. For example, the article may be a generally hollow vessel whose outer surface at least is provided by a non-solderable material such as aluminium. Such a vessel may be designed for use as a drinking vessel, in the manner of a traditional tankard for cold drinks or of a cup or mug for warm drinks. However, such vessels may be intended for other uses, such as for cooking when the vessel may be designed as a saucepan or as a casserole dish. The vessel may otherwise be used as a vessel in which material may be presented or stored. The vessel may also be designed as a sports trophy, tea or coffee pot, jug, ladle or spoon, ice bucket, and so on. Generally with such articles, the third component will be provided as a handle which is connected to the hollow vessel by means of a solder bond between the handle and the second component. Such articles are disclosed in our copending application which is filed on the same day as this application. The application is entitled "Hollow Vessel with Handle" and claims priority from UK patent application no. 9015144.0. The subject matter disclosed in that application is incorporated in the present application by this reference.

When the first component is in the form of a hollow vessel, the second component will generally take the form of a band which extends at least partly around the hollow vessel at or towards the open end thereof. The rim of the first component at the open end thereof can then be deformed over the second component so as to encapsulate it partially.

This arrangement, in addition to facilitating the formation of a connection to the first component, has the advantage that the second component reinforces the first component against deformation, to which it can be particularly prone at its open end, especially when the first component is formed from a thin sheet of material. Furthermore, force applied to the first component from the third component is spread over a larger region of the first component than would be the case if the third component were connected directly to the first component for example by means of a solder bond. The likelihood of such force causing deformation of the first component is therefore reduced.

The first component may take the form of an elongate tube in which the second component is at least partially encapsulated. Such an article may be arranged to have the appearance of an article which is formed from a rod or wire of a non-solderable material. For example, such an article formed from an aluminium may be arranged to appear as one wire, which may itself be arranged to appear as an article formed from a pewter wire. The technique of the invention can therefore be used to form articles which include intricate wire parts, for example which might act as a support. An example of such an article is a support for a vessel which is to be supported above a heat source so as to warm the contents of the vessel.

The article of the invention may include more than one second component or more than one third component or both, for example, two or more third components may be bonded to a single second component, and may therefore be attached to a first component. Alternatively or in addition, two second components may be provided on a single first component, for connection to two third components by means of bonds between respective pairs of second and third components.

The present invention may therefore be used to connect adjacent tubular sections of a tubular article by means of solder bonds, the surface of the article being provided by a non-solderable material. The invention therefore allows articles to be made to designs which involve a number of sections, as will be described by way of example below.

The solder material which is used to connect the second component to the third component may be a hard solder or a soft solder, depending on the nature of the article, its intended use and the materials of the components.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a cross-section through a first embodiment of drinking vessel;

Figure 2a is a plan view of a tray;

Figure 2b is a cross-section through the tray shown in Figure 2a, on the line B-B; Figure 3 is a cross-section through a tubular sectioned article, such as a candlestick;

Figure 4a is an isometric view of a composite wire article; and

Figure 4b is a cross-section through the article shown in Figure 4a, on the line B-B.

Referring to the drawings. Figure 1 shows an article which comprises a vessel 1 formed from aluminium. The vessel is formed by an automated spinning technique. The vessel may be anodised in order to increase the resistance of the aluminium to corrosion or to provide the aluminium with a coloured appearance. By appropriate finishing, the wall of the vessel can be arranged to have a shiny finish, a dull finish or a textured finish such as might be obtained by hammering, milling, engraving or knurling.

A second component in the form of a band 3 formed from brass wire having a circular cross-section, diameter 3mm, is located around the rim 5 of the vessel 1. The band 3 is held in place towards the rim 5 by deforming the rim over the band so that the band is almost completely encapsulated by the aluminium of the vessel 1.

The aluminium of the vessel 1 is a non-solderable material for the purposes of the present invention because of the highly reactive nature of fluxes which it is necessary to use in order to form a solder bond to it. The brass of the band 3 is a solderable material, and therefore allows the formation of a connection to the vessel 1 by means of a solder bond, the connection being through the band 3. However, the band 3 is almost completely encapsulated by the rim of the vessel which is bent over the band, so that the band is almost completely hidden from view in the finished article. The provision of the band 3 around the rim 5 of the vessel 1 has the further advantage of strengthening the vessel in the region of the rim, where it is particularly vulnerable to damage.

A third component in the form of a handle 7 is connected at one end 9 to the band 3 by means of a solder bond. The other end 11 of the handle 7 is connected to the vessel 1 by means of a band 13 formed from a strip of brass. The band 13 is positioned around the vessel 1 while expanded by heating, and is allowed to shrink onto the vessel as it cools. The end 11 of the handle 7 is connected to the band 13 by means of a solder bond.

The technique of the present invention makes it possible to connect the handle 7 to the vessel 1 after the vessel 1 has been finished, with reduced risk of impairing that finish than would exist if the handle were to be connected directly to the vessel.

Figure 2 shows a tray which comprises a first component 21 in the form of a flat sheet. The sheet is formed from a stainless steel. A second component in the form of a split ring, formed from a copper wire having a square cross-section of side 2mm, is located around the circumference of the sheet 21 , the edge 25 of the sheet 21 having been deformed over the band 23 so as to encapsulate it almost completely. Two third components in the form of handles 27, 29 are connected to the rim 25 by means of solder bonds between each of the ends of each of the handles and the band.

Figure 3 shows a candlestick 41 which comprises a plurality of sections 43, 45, 47, 49. Each section comprises a tubular body of aluminium which has been formed by drawing. Each section has an open circular band at each end of it, the bands being partly encapsulated by the material of the body. At one end of each of the sections 43, 45, 47, 49, the band is positioned inside the body and the rim of the body at that end is deformed inwardly over the band. At the other end of the body, the band is positioned outside the body and the rim is deformed outwardly so as to encapsulate the band. .

An elongate tubular article is formed by stacking adjacent sections coaxially and forming solder bonds between the bands 51 which are encapsulated by the material of adjacent sections. It will be noticed that each of the sections 43, 45, 47, 49 is tapered inwardly from one end towards the other end. In order to connect adjacent sections, the narrow end of one section is inserted into the wide end of an adjacent section. It may be necessary to deform the wide end of the receiving section inwardly in order to bring the encapsulated bands sufficiently close to one another to form a solder bond between them.

Figure 4 shows a composite wire which might be used to form an article such as a support for a pipe, or a support for a vessel holding fluid above a heat source such as a candle, in order to warm the fluid (in the vessel). The composite wire 61 comprises a first component in the form of a sheet 63 of aluminium. The sheet 63 is deformed around a wire 65 formed from copper and having a circular cross-section. The edges of the sheet 63 are joined together along the length of the composite wire 61 by welding. Where it is desired to form a connection to the composite wire by means of a solder bond, the aluminium is removed from the surface, for example by filing so as to expose the underlying copper below, as shown generally at the point 67 in Figure 4.

The composite wire shown in Figure 4 also may be made by drawing down an aluminium tube onto a copper wire.

Claims

CLAIMS :

1. An article which comprises a first component (1 ) formed from a metal whose surface is non-solderable, the first component being disposed around a second component (3) whose surface is provided by a solderable material, so as to encapsulate the second component partially, and a third component (7) which is connected to the first component by means of a solder bond between the second and the third components.

2. An article as claimed in claim 1 , in which the first component (1) is hollow.

3. An article as claimed in claim 2, in which the second component (3) extends around at least part of the perimeter (5) of the first component.

4. An article as claimed in claim 3, in which the first component (1) has an open end, and in which second component (3) extends around the perimeter (5) of the first component at or towards the said open end.

5. An article as claimed in any one of claims 2 to 4, in which the third component (7) is a handle for the article.

6. An article as claimed in claim 1 , which has an elongate configuration, in which the first component (63) has the configuration of an elongate tube, in which the second component (65) is at least partly encapsulated.

7. An article as claimed in any one of claims 1 to 6, in which the second component (3) includes a formation to which the solder connection to the third component is made.

8. An article as claimed in any one of claims 1 to 7, which includes more than one second component (3) .

9. An article as claimed in any one of claims 1 to 8, which includes more than one third component (7) .

10. An article (41) as claimed in any one of claims 1 to 9, in which the third component comprises first and second sub¬ components, the first sub-component (43) being formed from a metal whose surface is non-solderable, and being disposed around the second sub-component (51) whose surface is provided by a solderable material, so that the first sub-component encapsulates the second sub-component at least partially.

11. An article as claimed in any one of claims 1 to 10, in which the metal of the first component (1) is aluminium.

12. A method of making a connection to a first component (1 ) formed from a metal and whose surface is provided by a non-solderable material, the method comprising:

(a) deforming the first component around a second component (3) whose surface is provided by a solderable material so as to encapsulate the second component at least partially; and

(b) connecting a third component (7) to the first component by means of a solder bond between the second and third components.

13. A method as claimed in claim 12, which includes the step of modifying the appearance of the surface of the first component (1 ) .

14. A method as claimed in claim 13, in which the surface modification step takes place before the connection between the second and third components (3, 7) is made.