US3883949A

US3883949A - Reed switch manufacture

Info

Publication number: US3883949A
Application number: US423735A
Authority: US
Inventors: John Hill; Henryk Turczanski
Original assignee: Comtelco UK Ltd
Current assignee: Comtelco UK Ltd
Priority date: 1973-02-06
Filing date: 1973-12-11
Publication date: 1975-05-20
Anticipated expiration: 1992-05-20
Also published as: GB1381701A

Abstract

A method for precisely positioning the conductive elements of an electrical device within a sealed enclosure. As applied to the manufacture of high accuracy reed switches, the method includes the steps of initially disposing the contact reed blades (reeds) of the switch in the relative position desired in the finished product; rigidly joining the reeds within a region adjacent the respective contact areas to maintain the established geometry; sealing the reeds within an enclosure while joined as aforesaid to retain the established relative position; and thereafter eliminating the connection joining the reeds within the sealed enclosure to provide a completed switch with contacts permanently and precisely spaced in accordance with the pre-established relative position.

Description

United States Patent [191 Hill et a1.

[ REED SWITCH MANUFACTURE [75] Inventors: John Hill, Bickley; Henryk Turczanskl, Beckenham, both of England [73] Assignee: Comtelco (U.K.) Limited, Tonbridge, Kent, England [22] Filed: Dec. 11, 1973 [21] Appl. No.: 423,735

[30] Foreign Application Priority Data Feb. 6, 1973 United Kingdom 5839/73 [52] [1.8. CI 29/622; 29/418 [51] Int. Cl 1323p 17/00 [58] Field of Search 29/622, 628, 203, 418, 29/623; 335/151, 152, 153

[56] References Cited I UNITED STATES PATENTS 2,696,543 12/1954 Ellwood 200/165 2,978,556 4/1961 Lohs et al. 335/152 3,284,876 11/1966 Buttel 29/622 3,345,593 10/1967 Grengg 29/404 3,369,291 2/1968 Shaffer et a1. 29/622 3,432,282 3/1969 Schulz 65/32 3,443,312 5/1969 Moriyama et a1 29/622 3,550,268 12/1970 Santi 29/622 TIMER #98 ME LTING CURRENT SOURCE [4 1 May 20, 1975 3,568,310 3/1971 Neuber 29/622 FOREIGN PATENTS OR APPLICATIONS 1,513,486 10/1969 Germany 29/623 1.184.015 12/1964 Germany 29/622 Primary Examiner--C. W. Lanham Assistant Examiner-James R. Duzan Attorney, Agent, or Firm-Weingarten, Matham & Schurgin [57] ABSTRACT A method for precisely positioning the conductive elements of an electrical device within a sealed enclosure. As applied to the manufacture of high accuracy reed switches, the method includes the steps of initially disposing the contact reed blades (reeds) of the switch in the relative position desired in the finished product; rigidly joining the reeds within a region adjacent the respective contact areas to maintain the established geometry; sealing the reeds within an enclosure while joined as aforesaid to retain the established relative position; and thereafter eliminating the connection joining the reeds within the sealed enclosure to provide a completed switch with contacts permanently and precisely spaced in accordance with the pre-established relative position.

11 Claims, 13 Drawing Figures PATENIED RAYZOIHIS SHEEI 2 BF 3 ANNEALING 'CURRENT SOURCE TIMER MELTING CURRENT SOURCE REED SWITCH MANUFACTURE FIELD OF THE INVENTION The present invention relates in general to a method for precisely positioning and assembling the component parts of an electrical device, and more particularly concerns a method for the precise and uniform placement of electrical elements in electrical devices such as reed switches, mercury wetted sealed contacts, neon lamps, and multiple contact encapsulated switches.

BACKGROUND OF THE INVENTION The invention, while applicable to a wide variety of electrical devices in which contacts must be oriented precisely with respect to each other within an enclosure for requisite accuracy, stability and long life, the principles and objects of this invention will be fully explained with specific reference to the efficient, low cost manufacture of high quality reed switches heremctically sealed in glass or comparable materials.

The course of development of reed switches is de scribed in detail in an article entitled Development of Reed Switches and Relays" by O. M. Hovgaard and G. E. Perreault, Bell System Technical Journal, Vol. 34, No. 2. March l955, pp. 309 33?.. Typical prior methods for assembling reed swithces are described in E. L. Pityo, U.S. Pat. No. 3,537,276, entitled Method of and Apparatus for Producing Magnetic Reed Switches,

dated Nov. 3, 1970, and in P. M. Zollman, US. Pat.

No. 3,628,242, entitled Manufacture of Electrical Switches, dated Dec. 2t, 1971.

More specifically the Pityo patent discloses a fabrica tion technique in which a pair of reed blades are each held by a respective jaw mechanism within a glass sleeve disposed around the blades. The reed blades are caused to engage, or latched to one another by an applied magnetic field, one jaw is released and the confronting unsecured end of the glass sleeve sealed to the associated lead portion of the reed blade. Thereafter the magnetic latching force is removed, the unsealed reed blade is displaced by a predetermined amount to define the desired gap between the contacts, and this reed blade is then sealed to the associated end of the glass envelope to complete the assembly. The technique proposed by Zollman is similar and employes a pair of reed blades magnetically held in overlapping relationship by a jaw affixed to one of the reed blades. A glass sleeve is installed over the magnetically held reed blades and the end of the glass adjacent the unsecured reed blade is sealed to this reed blade. The magnetic force is then removed and the second reed blade displaced laterally from the first by a predetermined amount to establish the contact gap. The displaced reed blade is then sealed to the glass sleeve to complete the device.

The teachings of both Pityo and Zollman necessarily require the fabrication and utilization of assembly machines which are inherently complex, both mechanically and electrically, and require highly skilled labor to maintain production efficiency and economy. Both combine the functions of accurately positioning the switch contact reed blades and sealing them into the glass envelope. Resultantly, inaccuracies areintroduced due to expansion as positioning mechanisms become heated in the course of sealing the glass envelopes.

German Pat. No. l,l 84,015 published Dec. 23, I964 discloses a manufacturing technique whereby the reed blades initially constitute integral central portions of a generally open rectangular metal frame. The entire frame is first placed in a press which crimps the structure and brings the contact portions into predetermined alignment to define the contact gap. A glass enclosure is slipped over and sealed to the aforesaid reed blade portions while still integral with the frame and in a final step, the exterior portions of the frame are cut away, leaving a completed reed switch. During the sealing step the inner confronting ends of the blades are free; therefore, as set forth above with reference to the prior Pityo and Zollman patents, distortion of the blades due to expansion and contraction during the sealing operation limits the accuracy to which reed switches may be made using this technique.

Other patents which disclose pertinent prior tech' niques and structure and are thus useful in providing a fuller understanding of this art are: US. Pat. Nos. 2,696,543; 2,978,556; 3,284,876; 3,345,593; 3,369,29l; 3,432,282; 3,550,268; 3,568,310; and German Pat. No. 1,904,099; and a useful reference work which provides a comprehensive discussion of reed switches and their operating characteristics is Designers Handbook and Glossary of Terms relative to reed relays available from Magnecraft Corporation, Chicago, lll.

SUMMARY OF THE INVENTION The present invention discloses and has as a primary object the provision of a method of precisely positioning electrical contacts in a sealed enclosure. in the application ofthe principles of this invention to the manufacture of reed switches, the reed blades are first firmly secured with a fixture in the relative position desired for the finished switch. While so constrained within the fixture, the reed blades are rigidly joined together by welding an electrically conductive strap across the two to form a bridge within a region adjacent the respective confronting active contact areas (contacts), and the strap is thereafter annealed to relieve any internal stresses which may have been caused by the welding operating. During welding and annealing operations care is taken to prevent oxidation of the components, inert or reducing gas (such as nitrogen for example) may be directed towards and over the components during such operations. After removal from the fixture, the reed blades and interconnecting bridge may be handled as an integral assembly during each subsequent production step such as cleaning, automatic feeding and the like, and this assembly is sealed as an integral unit into a glass envelope having a preferred inert atmosphere. The reed blades precisely retain their predetermined relative orientation during the aforesaid sequence of process steps by virtue of the integral substantially rigid assembly provided. An electrical current pulse of predetermined magnitude is then passed through the assembly from an external source to melt the briding strap and thus mechanically disconnect the reed blades in the position initially established in the preassembly fixture.

The precise characteristics of the melting current are chosen not only to melt the strap, but also to preclude disfiguration of the active contact areas by the melted matter evaporating and spattering on them. The bridging strap may itself be composed of magnetic material and the melting current pulse selected such that melted material flows and solidifies on the reeds in the switch ing area (but not on the confronting contacts) thereby adding a mass of magnetic material to enhance switching performance.

Complex mechanisms for positioning and gapping during the sealing operation are thus unnecessary, and as a consequence, inaccuracies due to non-uniform expansion of a positioning mechanism as can occur by prior assembling means, during the sealing operation are virtually eliminated. The apparatus required for practice of this invention is inherently simple, particularly since the sealing function has been made independent of the gap control function. Volume production of the highest quality components at minimum cost is thus achieved.

DESCRIPTION OF THE DRAWING The invention will be more fully understood by reference to the following detailed description when taken in conjunction with the drawing in which:

FIG. 1 is a pictorial view of a reed switch according to the present invention;

FIG. 2 is a pictorial view ofa fixing having means for providing precise reed blade alignment and contact gap spacing;

FIG. 3 is a pictorial view of a pair of reed blades held in the fixture of FIG. 2 by magnetic means, where the reed blade contact overlap is precisely defined by a removable stop;

FIG. 4 is a pictorial view of a pair of reed blades in a fixture having an alternative form of reed blade retaining means;

FIG. 5 illustrates a strap welded to the reed blades forming a conductive. rigid bridge across the gap between contact areas;

FIG. 6 illustrates electrical annealing apparatus for relieving strains in the welded strap;

FIG. 7 shows the glass encapsulated strapped reed blades connected to a melting current source;

FIG. 8A shows a pair of reed blades bridged by an alternative form of welded strap;

FIG. 8B illustrates a completed reed switch embodying the reed blade and strap configuration of FIG. 8A;

FIG. 9A shows another alternative pair of reed blades joined by a welding strap;

FIG. 9B shows a completed reed switch embodying the reed blade and strap configuration of FIG. 9A;

FIG. 10A shows still another alternative reed blade and strap structure; and

FIG. [08 illustrates a completed reed switch embodying the reed blade and strap configuration of FIG. [0A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A normally open reed switch constructed according to the principles of the present invention is depicted in FIG. 1. More specifically, a pair of generally flat, magnetic and

conductive reed blades

10 and 12 are disposed in closely adjacent, partially overlapping, spaced relationship within an elongated sealed enclosure 14 of glass of like material. The reed blade is a unitary or integral structure which may be formed of either a single metal or alloy of a composite of differing materials. Typically, the reed blades are formed of a metal suitable for hermetic sealing to glass such as a 50-50 nickel-iron magnetic alloy. Alternatively. a composite reed blade structure can be employed having, for example, a Dumet section for glass sealing and a 70-30 ironnickel magnetic alloy for the blade portion. Reed blades I0 and I2 are formed with integral cylindrical lead portions I6 and 18, respectively, which are her metically sealed into the

ends

20 and 22 of enclosure 14, and serve as electrical connecting leads for the device. A suitable inert atmosphere is provided within enclosure 14.

The reed blades 10 and I2 are of generally thin, rectangular cross-section, with the overlapping, confronting, flat surfaces at the inner ends thereof constituting electrical contact areas (contacts) 24 and 26. The flat portions of the reed blades are flexible and are normally in the open electrical condition shown. In response to the application ofa predetermined solenoidal magnetic field from a source (not shown) the reed blades flex toward each other causing the

contacts

24 and 26 to close.

Metal segments

28 and 30 are shown welded to

respective reed blades

10 and 12, the significance of which will be presently described.

According to the invention, the reed blades are retained as an integral assembly throughout the manufacturing process in a precise spatial arrangement. During an initial step of the manufacturing process, a fixture 32 shown pictorially in FIG. 2 is employed to precisely position the reed blades in the desired final operating position, for subsequent assembly. Fixture 32 includes first and

second pedestals

34 and 36, the latter being of greater height than pedestal 34 by a predetermined amount corresponding to the desired gap spacing between contact areas, typically 3-5 mils. A rectangular groove 38 is provided the length of pedestal 34, while a similar groove 40 is provided in pedestal 36 and in parallel with groove 38.

Grooves

38 and 40 are arranged to accommodate the rectangular reed blades in the manner illustrated in FIG. 3, and when inserted, the reed blades are retained therein by action of

magnets

42 and 44 provided within the respective fixture pedestals 34 and 36. In this stage of assembly, the reed blade 10 is butted against the vertical surface of step 37 of pedestal 36, while reed blade 12 is placed with its inner end extending beyond the step surface an amount governed by the position of a stop 46. The bar is adjustable laterally as suggested by double arrow 48 to control the amount of overlap of the confronting end portions of reed blades 10 and I2, and once the reed blades have been properly positioned in fixture 32, stop bar 46 is removed as suggested by arrow 50. The mechanical expedients providing lateral adjustment and pivotal motion of stop 46 are considered within the skill of the art, and have been omitted from the drawing.

An alternate arrangement for maintaining the precise relative disposition of

reed blades

10 and 12 in fixture 32 is depicted in FIG. 4 wherein a pair of

mechanical clamps

52 and 54 are provided for retaining reed blades 10 and I2 during initial assembly instead of magnets, although both clamps and magnets may be used. The overlap of the reed blades is again defined by a stop (not shown) which may be the same as stop 46 in FIG. 3.

Clamps

52 and 54 are pivotable about the axis of a support rod 56, with respective ends 58 and 60 arranged to press upon respective reed blades I0 and 12 to retain the physical relationship shown. As in the case of FIG. 3, this arrangement insures exact alignment. gap spacing, overlap and parallelism of the blade surfaces.

With reference now to FIG. 5. a rigid wire strap 62 of electrically conductive material is shown welded between reed blades I0 and I2 near the respective contact areas thereof. thus electrically and mechanically bridging the spaced reed blades to form an integral structure which maintains the predetermined spaced relationship After welding strap 62 into place. but prior to removal from fixture 32 of the integral assembly provided by the bridged reed blades and I2, strap 62 is annealed to relieve the internal stresses therein which might otherwise cause misalignment or distortion ofthe fixed relation of

reed blades

10 and 12 after removal from the holding fixture. Annealing may be accomplished as shown in FIG. 6 by connection to annealing current source 64 having output leads 66 and 68 connected to

terminals

70 and 72 which are maintained in good electrical contact with

respective reed blades

10 and 12 by a suitable mechanism. A timer 74 is coupled to current source 64 to govern the duration of operation of the latter during which current is supplied via

terminals

70 and 72 to read blades l0 and 12 and to the interconnected bridging strap 62. Reed blades I0 and I2 are firmly held in position by

magnets

42 or 44 or the clamp arrangements of FIG. 4 during this annealing step. Fixture 32 is of an electrically insulative material or includes insulation within grooves 38 and to confine the annealing current flow to the path provided by reed blades 10 and I2 and strap 62. Due to the smaller cross-section of the strap 62, the annealing current pulse, which is of prearranged magnitude and duration selectively raises the temperature of the strap to the annealing temperature for the metal used. to relieve all internal stresses and strains.

The integral reed blade assembly accurately maintains the spatial relationship of the reed blades including the confronting contact areas thereof, and this reed blade assembly can after removal from the fixture of FIG. 6 be handled during subsequent steps of device fabrication without affecting the precise relationship between the first and second reed blades. Prior to the encapsulation within a sealed glass envelope, the integral reed assembly may be processed through desired ultrasonic cleaning and drying operations, and may be atuomatically machine fed without in any way altering the precise and rigidly maintained parallel confronting relationship of the reed blades and their associated contact areas.

The integral reed blade assembly is then hermetically sealed within a glass envelope I4. If composite reed blades are employed, the envelope is sealed to the Dumet portion of the reed blades. After hermetically sealing of envelope I4 to leads I6 and I8, and as a final step in the novel process, strap 62 is melted to isolate reed blades 10 and I2. Referring now to FIG. 7, the leads l6 and 18 are connected to a melting current source 88 such as by conductive terminal clips 90 and 92 and interconnecting leads 94 and 96. Timer 98 controls current source 88 and determines the interval during which current is applied through the reed blade and strap assembly. As in the case of the annealing current described in connection with FIG. 6, the higher resistance of strap 62 causes it to heat to a much higher temperature than

reed blades

10 and 12. The strap melts while the reed blades remain relatively cool, and thus electrically separates the reed blades within the enclosure. The welded ends 28 and 30 of strap 62 remain on the reed blades, as shown in FIG. I. The melting of strap 62 electrically isolates the

reed blades

10 and 12 to provide a normally open reed switch. The glass enclosure and the respective hermetic glass-to metal seals now permanently retain the reed blades 10 and I2 in precisely the mechanical interrelationship established in the assembly fixture shown in FIG. 5.

The characteristics of the melting current are selected for the strap 62 to prevent the melted metal from spattering or evaporating on to the contacts, which could affect the electrical performance and reliability of the completed device.

Noting as in FIG. I, that a portion of each end of strap 62 remains near a respective reed blade contact, performance of the completed switch may be enhanced by using conductive magnetic material for strap 62. In this manner welded ends 28 and 30, FIG. I, add to the magnetic mass of the reed blades and aid in the response thereof to an applied solenoidal magnetic field.

In accordance with this invention, the configuration of the reed blades and contacts may be varied in form to suit particular needs and to impart specific characteristics. Alternate reed blade and contact arrangements are shown as examples in FIGS. 8-I0, inclusive. Referring to FIG. 8A. reed blades I00 and 102 are dis posed coaxially with the blade surfaces in parallel and with a conductive strap I04 welded to the reed blades and bridging the space I06 between the reed blade ends. Strap 104 includes an integral contact section I08 which extends a small predetermined distance over the inner end portion of reed blade I00 and which is spaced therefrom by a selected amount to define the contact gap. A necked-down integral section of element 104 provides a high electrical resistance. meltable link which is sufficiently rigid to retain the assembly as shown through each process step including encapsulation of the integral reed blade assembly within an envelope 112 as depicted in FIG. 8B. As above, a melting current pulse is used to selectively burn-out the necked-down section 110 to yield the finished switch, as in FIG. 8B.

A variation of the reed blade assembly of FIG. 8A is illustrated in FIG. 9A wherein reed blades II4 and 116 are again arranged coaxially, with a contact element 118 welded to the inner end of reed blade 116 and extending over the inner end of reed blade I14 and spaced therefrom to define the contact surfaces and gap. A meltable conductive element I20 having a reduced area, high resistance section in the center thereof is welded between the reed blades as shown. After encapsulation as before in glass enclosure I22 link I20 is melted by an applied current to isolate the reed blades electrically and complete the switch, as shown in FIG. 9B.

Still another reed blade and strap configuration is shown in FIG. 10A, where a single flexible reed blade I24 is associated with a contact element 126 conductively attached to lead I28. A wire strap I30 is welded between the inner end of reed blade I24 and a flat surface on member I26 to rigidly maintain the desired spaced interrelationship of the confronting contact areas during switch assembly. After the integral reed blade assembly is sealed within an envelope 132, as shown in FIG. IOB, strap 130 is melted to electrically isolate the contacts and complete the device. In FIGS. 8-10 inclusive. the reed blades are magnetic as shown in FIG. 1, and the respective straps may also be magnetic for the advantageous characteristic previously set forth.

It will be appreciated that the invention may be implemented by various alternative structures utilizing the steps herein set forth to meet specific requirements. Moreover, the reed switches fabricated according to the principles of this invention may be varied. for example, to have double pole or double throw action, without departing from the spirit of the invention. and generally related electrical devices may be made embodying the same process techniques. Accordingly, it is not intended to limit the invention to that which has been particularly shown and described, but only as indicated by the scope of the appended claims.

What we claim is:

l. A method for precisely positioning a pair of coacting conductive switch contacts within a scaled enclosure comprising the steps of:

disposing said contacts in a fixed predetermined spatial relationship;

rigidly joining said contacts with an electrically conductive meltable connection while in said fixed predetermined spatial relationship;

sealing said contacts while joined as aforesaid within an enclosure whereby said rigid connection retains said contacts in said predetermined spatial relationship; and

eliminating said connection between said contacts by melting said rigid connection within said enclosure.

2. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim l and including:

the step of relieving stresses and strains in said meltable connection after rigidly joining said contacts.

3. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 1 wherein:

said contacts are joined by welding a rigid meltable metal strap across said contacts; and

an electrical current is directed through said contacts and welded strap to heat and anneal said strap to relieve residual stresses and strains therein while said contacts remain in said fixed predetermined spatial relationship.

4. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 3 wherein:

said contacts when rigidly joined by said welded meltable metal strap are disposed in fixed overlapping relationship in the region of said strap.

5. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 4 wherein:

said contacts, when disposed in said predetermined overlapping relationship are separated in the region of said overlap to provide a gap between the respective confronting surfaces thereof.

6. A method of fabricating an electrical reed switch comprising the steps of:

disposing first and second electrically conductive,

magnetic reed blades in a fixed predetermined spatial relationship defining confronting switch contacts;

rigidly joining said reed blades with a rigid meltable conductive metal strap while said reed blades are disposed in said fixed predetermined spatial relationship; relieving stresses and strains in said meltable metal strap while said reed blades are firmly maintained 5 in said fixed predetermined spatial relationship thereby providing a self supporting integral assembly of said reed blades and strap; sealing said integral assembly within a rigid enclosure with selected portions of said reed blades extending outwardly therefrom while said rigid metal strap remains joined to said reed blades entirely within said enclosure; and directing an electrical current serially through said reed blades and said strap to melt and burn-out said within said sealed enclosure to provide electrical separation of said reed blades within said enclosure, with said enclosure providing rigid mechanical support for said reed blades; 7. A method of fabricating an electrical reed switch comprising the steps of:

disposing and firmly retaining first and second electrically conductive, magnetic reed blades each having a flexible relatively flat spatial and an integral lead portion in a fixed spatiall relationship with said flat portions spaced and overlapping in part to define confronting switch contacts having a predetermined gap; welding a rigid meltable conductive metal strap to said reeds across said gap while said reed blades are firmly retained as aforesaid in said fixed predetermined spatial relationship; directing an electrical current through ssaid reed blades and strap to heat and anneal said strap to receive stresses and strains therein while said reed blades are firmly maintained in said fixed predetermined spatial relationship, thereby providing a self supporting integral assembly of said reed blades and strap; hermetically sealing said integral assembly within a tubular glass enclosure with said lead portions of said reed blades extending outwardly therefrom while said rigid metal strap remains joined to said reed blades entirely within said glass enclosure; and

directing an electrical current serially through said reed blades and said strap within said sealed glass enclosure to selectively melt and burn-out said strap to provide electrical separation of said reed blades within said glass enclosure, with said glass providing rigid mechanical support for said reed blades.

8. A method for precisely positioning a pair of coacting conductive elements within a sealed enclosure comprising the steps of:

disposing first and second elements in a fixed predetermined spatial relationship;

rigidly joining said elements with an electrically conductive meltable strap while in said fixed predetermined spatial relationship;

sealing said elements while joined as aforesaid within an enclosure whereby said rigid connection retains said elements in said predetermined spatial relationship; and

eliminating said connection between said elements by melting said rigid strap within said enclosure.

9. A method for precisely positioning a pair of coacting conductive elements according to claim 8 wherein:

said first and second elements comprise reed blades;

said step of disposing said elements includes the step of positioning said reed blades along a common linear axis defining a gap between confronting ends of said reed blades along said common axis; said strap comprises a contact section attached to one of said reed blades and confronting a portion of said other reed blade in overlapping spaced relationship defining confronting switch contacts, and an integral fuse section joining said contact section to said second reed blade; and said eliminating step includes the step of melting said fuse section. 10. A method for precise positioning a pair of coactive conductive elements within a sealed enclosure according to claim 8 wherein said disposing step includes LII fronting ends thereof.

Claims

1. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure comprising the steps of: disposing said contacts in a fixed predetermined spatial relationship; rigidly joining said contacts with an electrically conductive meltable connection while in said fixed predetermined spatial relationship; sealing said contacts while joined as aforesaid within an enclosure whereby said rigid connection retains said contacts in said predetermined spatial relationship; and eliminating said connection between said contacts by melting said rigid connection within said enclosure.

2. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 1 and including: the step of relieving stresses and strains in said meltable connection after rigidly joining said contacts.

3. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 1 wherein: said contacts are joined by welding a rigid meltable metal strap across said contacts; and an electrical current is directed through said contacts and welded strap to heat and anneal said strap to relieve residual stresses and strains therein while said contacts remain in said fixed predetermined spatial relationship.

4. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 3 wherein: said contacts when rigidly joined by said welded meltable metal strap are disposed in fixed overlapping relationship in the region of said strap.

5. A method for precisely positioning a pair of coacting conductive switch contacts within a sealed enclosure in accordance with claim 4 wherein: said contacts, when disposed in said predetermined overlapping relationship are separated in the region of said overlap to provide a gap between the respective confronting surfaces thereof.

6. A method of fabricating an electrical reed switch comprising the steps of: disposing first and second electrically conductive, magnetic reed blades in a fixed predetermined spatial relationship defining confronting switch contacts; rigidly joining said reed blades with a rigid meltable conductive metal strap while said reed blades are disposed in said fixed predetermined spatial relationship; relieving stresses and strains in said meltable metal strap while said reed blades are firmly maintained in said fixed predetermined spatial relationship thereby providing a self supporting integral assembly of said reed blades and strap; sealing said integral assembly within a rigid enclosure with selected portions of said reed blades extending outwardly therefrom while said rigid metal strap remains joined to said reed blades entirely within said enclosure; and directing an electrical current serially through said reed blades and said strap to melt and burn-out said within said sealed enclosure to provide electrical separation of said reed blades within said enclosure, with said enclosure providing rigid mechanical support for said reed blades.

7. A method of fabricating an electrical reed switch comprising the steps of: disposing and firmly retaining first and second electrically conductive, magnetic reed blades each having a flexible relatively flat spatial and an integral lead portion in a fixed spatiall relationship with said flat portions spaced and overlapping in part to define confronting switch contacts having a predetermined gap; welding a rigid meltable conductive metal strap to said reeds across said gap while said reed blades are firmly retained as aforesaid in said fixed predetermined spatial relationship; directing an electrical current through ssaid reed blades and strap to heat and anneal said strap to receive stresses and strains therein while said reed blades are firmly maintained in said fixed predetermined spatial relationship, thereby providing a self supporting integral assembly of said reed blades and strap; hermetically sealing said integral assembly within a tubular glass enclosure with said lead portions of said reed blades extending outwardly therefrom while said rigid metal strap remains joined to said reed blades entirely within said glass enclosure; and directing an electrical current serially through said reed blades and said strap within said sealed glass enclosure to selectively melt and burn-out said strap to provide electrical separation of said reed blades within said glass enclosure, with said glass providing rigid mechanical support for said reed blades.

8. A method for precisely positioning a pair of coacting conductive elements within a sealed enclosure comprising the steps of: disposing first and second elements in a fixed predetermined spatial relationship; rigidly joining said elements with an electrically conductive meltable strap while in said fixed predetermined spatial relationship; sealing said elements while joined as aforesaid within an enclosure whereby said rigid connection retains said elements iN said predetermined spatial relationship; and eliminating said connection between said elements by melting said rigid strap within said enclosure.

9. A method for precisely positioning a pair of coacting conductive elements according to claim 8 wherein: said first and second elements comprise reed blades; said step of disposing said elements includes the step of positioning said reed blades along a common linear axis defining a gap between confronting ends of said reed blades along said common axis; said strap comprises a contact section attached to one of said reed blades and confronting a portion of said other reed blade in overlapping spaced relationship defining confronting switch contacts, and an integral fuse section joining said contact section to said second reed blade; and said eliminating step includes the step of melting said fuse section.

10. A method for precise positioning a pair of coactive conductive elements within a sealed enclosure according to claim 8 wherein said disposing step includes positioning said elements along a common linear axis and defining a gap along said axis and between the confronting ends thereof; and including the step of attaching a rigid conductive metal member to one of said elements, said member being disposed across said gap and in overlapping spaced relationship with the other element to define switch contacts.

11. A method for precisely positioning a pair of coacting conductive elements within a sealed enclosure according to claim 10 wherein said elements are joined by welding a rigid meltable metal strap across the confronting ends thereof.