US3810068A - Impedance element with magnesium reaction terminal contact and method - Google Patents
Impedance element with magnesium reaction terminal contact and method Download PDFInfo
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- US3810068A US3810068A US00358014A US35801473A US3810068A US 3810068 A US3810068 A US 3810068A US 00358014 A US00358014 A US 00358014A US 35801473 A US35801473 A US 35801473A US 3810068 A US3810068 A US 3810068A
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- fusible
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- impedance element
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- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 239000011777 magnesium Substances 0.000 title claims abstract description 68
- 229910052749 magnesium Inorganic materials 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims description 51
- 239000011195 cermet Substances 0.000 claims abstract description 34
- 239000000463 material Substances 0.000 claims abstract description 32
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 12
- 239000011521 glass Substances 0.000 claims description 27
- 235000012431 wafers Nutrition 0.000 claims description 12
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 239000000395 magnesium oxide Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 5
- 230000009467 reduction Effects 0.000 claims description 5
- 239000011324 bead Substances 0.000 abstract description 21
- 235000001055 magnesium Nutrition 0.000 description 46
- 239000010408 film Substances 0.000 description 14
- 238000007789 sealing Methods 0.000 description 12
- 238000005538 encapsulation Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 6
- 239000000758 substrate Substances 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000004382 potting Methods 0.000 description 4
- 239000012789 electroconductive film Substances 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 229910000765 intermetallic Inorganic materials 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910001887 tin oxide Inorganic materials 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- -1 Mg Si Substances 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910000410 antimony oxide Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002241 glass-ceramic Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000005355 lead glass Substances 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910001120 nichrome Inorganic materials 0.000 description 1
- 239000012811 non-conductive material Substances 0.000 description 1
- VTRUBDSFZJNXHI-UHFFFAOYSA-N oxoantimony Chemical class [Sb]=O VTRUBDSFZJNXHI-UHFFFAOYSA-N 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 230000001603 reducing effect Effects 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000005361 soda-lime glass Substances 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
- H01C1/144—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors the terminals or tapping points being welded or soldered
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49082—Resistor making
- Y10T29/49087—Resistor making with envelope or housing
- Y10T29/49098—Applying terminal
Definitions
- FIGS. 1 and 2 there is shown a resistor blank disposed within an insulating sleeve 12 of glass, glass-ceramic, ceramic or the like.
- Theinside diameter of sleeve 12 is very nearly the same as the outside diameter of blank 105 the spacing therebetween being preferably just sufficient to permit the blank to be easily inserted into the sleeve.
- One end of sleeve 12 may be fluted to facilitate insertion of blank 10.
- Blank 10 may consist of a substrate 14 having, for example, an electroconductive film 16 of tin and antimony oxides, nichrome, or the like deposited on the surface thereof.
- Sleeve 12 extends beyond the end of blank 10, and 1 the end of an external lead 24 is disposed near the end of blank 10 within the open end of sleeve 12.
- the end of lead 24 is preferably enlarged to provide improved electrical and mechanical contact with resistor blank 10.
- the end of lead 24 may be simply flattened or bent or a conductive disc 20, for example, may be welded or otherwise affixed to lead 24.
- Disposed between the end of disc 20 and substrate 14 is a magnesium wafer 18 which is utilized in the method of the present invention because of its low vaporization temperature and its reducing properties.
- the shape of wafer 10 preferably conforms to the geometry of the end of resistor blank 10.
- Resistor blank 10 is cut to providethe required resistance, and, if necessary, film 16 may be appropriately spiralled to achieve higher resistances.
- the resistor blank shown in FIG. 1 may be encapsulated and provided with external leads in accordance with the method of the present invention, or it may be provided with conductive end portions prior to encapsulation by this method.
- the ends of body 14 may be provided with a conductive film 38 in accordance with the teachings of U.S. Pat. No. 3,012,214 issued to R. W. Bronson et al.
- body 10 could be provided with conductive caps 42 as illustrated in FIG. 4.
- the embodiment illustrated in FIGS. 1 and 2 is preferred because it eliminates the steps required in the formation of the conductive end portions of FIGS. 3 and 4.
- Resistor blank 10 is placed insleeve 12, and magnesium wafers 18 and conductive discs 20 are disposed at the ends thereof, beads 26 being disposed on leads 24 intermediate the ends thereof. Sufficient pressure is applied to lead wires 24 to keep conductive discs 20, magnesium wafers l8 and resistor blank 10 in intimate contact during the subsequent sealing process.
- a method in accordance with claim 1 further comprising the step of urging said end of said lead toward said impedance element during the step of applying heat.
- a method in accordance with claim 6 further comprising the steps of urging said first ends of said first and second leads toward said impedance element during the step of applying heat.
- first and second fusible elements disposed about said first and second leads, respectively, intermediate the ends thereof, the coefficient of thermal expansion of said fusible elements being compatible with that of said encapsulating sleeve material, each of said fusible elements being fused to its corresponding lead and to the corresponding end of said sleeve, and
Abstract
An electrical impedance device is hermetically sealed within an encapsulating sleeve while external leads are simultaneously electrically connected thereto. The impedance element is disposed in an encapsulating sleeve which extends beyond the ends thereof. Magnesium is disposed within the ends of the sleeve, and one end of an external lead is placed in each end of the sleeve adjacent to the end of the impedance element. A bead of fusible material is disposed about the lead and is positioned adjacent to the end of the sleeve. Heat is applied to that portion of the assembly so formed including the bead and the end portion of the sleeve to cause the bead to form a hermetic seal with the lead and the sleeve and to cause the magnesium to vaporize and form a conductive cermet layer which forms an electrical connection between the lead and the electrical terminal of the impedance element. The magnesium also reacts with sleeve and bead to form a magnesium reaction product.
Description
[ 51 May 7,1974
IMPEDANCE ELEMENT WITH MAGNESIUM REACTION TERMINAL CONTACT AND METHOD Robert D. DeLuca, Big Flats, N.Y.
Corning Glass Works, Corning, NY.
Filed: May 7, 1973 Appl. No.: 358,014
Inventor:
Assignee:
[5 6] References Cited UNITED STATES PATENTS 2/1935 Spencer [17/222 X 8/1957 Dobischer 117/222 X 2/1967 Griest 338/237 Primary Examiner-E. A. Goldberg Attorney, Agent, or Firm-William J. Simmons, Jr.
[5 7] ABSTRACT An electrical impedance device is hermetically sealed within an encapsulating sleeve while external leads are simultaneously electrically connected thereto. The impedance element is disposed in an encapsulating sleeve which extends beyond the ends thereof. Magnesium is disposed within the ends of the sleeve, and one end of an external lead is placed in each end of the sleeve adjacent to the end of the impedance element. A bead of fusible material is disposed about the lead and is positioned adjacent to the end of the sleeve. Heat is applied to that portion of the assembly so formed including the bead and the end portion of the sleeve to cause the bead to form a hermetic seal with the lead and the sleeve and to cause the magnesium to vaporize and form a conductive cermet layer which forms an electrical connection between the lead and the electrical terminalof the impedance element. The magnesium also reacts with sleeve and head to form a magnesium reaction product.
19 Claims, 7 Drawing Figures IMPEDANCE ELEMENT WITH MAGNESIUM REACTION TERMINAL CONTACT AND METHOD BACKGROUND OF THE INVENTION This invention relates to impedance devices and more particularly to a method of encapsulating or hermetically sealing impedance elements while simultaneously providing electrical contact between the electrical terminals of the impedance elements and their external leads. This invention further relates to the resulting structures.
Impedance devices such as resistors, capacitors, diodes, inductors and the like are usually encapsulated to provide the impedance element with a thermal barrier, to protect the element from attack by excessive moisture or corrosion, to electrically insulate the element from adjacent elements or, in certain applications, all of these functions may be served.
The prior art methods of electrical component encapsulation fall into two general catagories, the first of which is a potting method whereby the impedance element is coated with an appreciably thick layer of potting material. The potting material is usually in a fluid or semi-fluid state when initially applied to the element and is subsequently allowed to harden about the body of the element to provide the necessary protective coating. The other method is one wherein the impedance element is hermetically sealed in a container that may be either evacuated or filled with an inert atmosphere.
These known methods of electrical component fabrication usually call for the prior forming or manufacture of the complete impedance element, including the connection of external leads thereto, and then the subsequent step of either potting or sealing. An improvement over these methods is disclosed in US. Pat. Nos. 3,220,097 and 3,307,134 issued to E. M. Griest, wherein the leads are connected to the element while the element is being simultaneously hermetically sealed in a nonconductive sleeve. Briefly, the method disclosed in the aforementioned Griest patents is as follows. After a sleeve of fusible encapsulating material is disposed about the impedance element, both the ends of the impedance element and the ends of the leads to be connected thereto are provided with a fusible conductive ceramic frit. A fusible bead is disposed on the leads which are inserted into the ends of the encapsulating sleeve so that the frit on the ends of the leads contacts the frit on the ends of the element. Heat generated by a sealing flame is conducted through the sleeve, bead and lead, and the temperature of the frit becomes higher than the softening point thereof so that the frit on the element and that on the leads becomes fused while the bead fuses to the lead and sleeve. Although this method results in the simultaneous sealing of an impedance element in a hermetic container and connection of leads thereto, it requires that fusible conductive ceramic frit 'be initially applied to both the leads and the impedance element and then fired before the encapsulating step can begin.
SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hermetically sealed impedance device that is noted by its ease of manufacture.
Another object of the.present invention is to provide a simple and economical method of forming hermetically sealed impedance devices.
A further object of this invention is to provide a method of forming an electrical component havingan evacuated, hermetically sealed enclosure.
Briefly, the present invention relates to an encapsulated impedance device comprising an impedance element having at least one electrical terminal having an end of an external lead disposed adjacent thereto. A sleeve of encapsulating material is disposed about the impedance element and the end of the external lead. A fusible element, having a coefficient of thermal expansion compatible with that of the encapsulating sleeve material, is disposed about the lead intermediate the ends thereof. The fusible element is fused to the lead and the sleeve to form a hermetic enclosure about the element. A cermet layer including magnesium and magnesium oxide, which is disposed upon the inner surfaces of the sleeve and fusible element and upon a portion of the impedance element and adjacent portion of the external lead, makes electrical contact between the impedance element and the external lead.
The encapsulated impedance device is formed in accordance with the following method. An impedance element having at least one electrical terminal at an end I thereof is provided, and a sleeve of fusible encapsulating material having at least one open end is disposed about the impedance element so that the open end extends beyond and provides access to the terminal. Magnesium is inserted into the open end of the sleeve, and an end of an external lead is placed into the open end of the sleeve. A fusible element is disposed about the lead intermediate the ends thereof. Heat is applied to that portion of the assembly so formed including the fusible element andthe adjacent portion of the sleeve to cause the fusible element to form a hermetic seal with the lead and the sleeve and to cause the magnesium to vaporize and form a conductive cermet layer which electrically connects the terminal and the lead.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. '1 is an exploded cross-sectional view of one end of a resistor blank indicating the components necessary to form an encapsulated resistor.
FIG. 2 is a cross-sectional view of one end of a completed resistor.
FIGS. 3 and 4 are cross-sectional views of the ends of impedance elements illustrating conductive'terminals which may be applied thereto prior to encapsulation.
FIGS. 5, 6 and 7 are cross-sectional views illustrating different forms in which magnesiums may be present during the encapsulation process. FIG. 5 shows powder or granules disposed on the resistor blank. In FIG. 6 a sheet of magnesium foil is affixed to an external lead, and in FIG. 7 the external lead is provided with magnesium paste prior to encapsulation.
DETAILED DESCRIPTION The process of the present invention and the product resulting therefrom will be described in terms of the components. As used herein, the term element or impedance element refers to the initially formed portion of an electrical impedance device or component prior to encapsulation and attachment of external leads thereto. The electrical terminals of such an element are either the actual ends of the impedance forming parts of the element or a conductive coating or end cap which is formed on the element in contact with the actual impedance forming part. For example, a resistor element, which is'often referred to as a resistor blank, comprises a substrate upon which is disposed an impedance forming part which may be a coil of wire, an electroconductive film or the like. Opposite ends of the film or wire may be considered to be the terminals of the element, or the terminals may be conductive films or caps in contact with the end portions of the film or wire. Theconnection of external leads to the electrical terminals of the element and the encapsulation thereof results in an impedance device or component.
Referring now to FIGS. 1 and 2 there is shown a resistor blank disposed within an insulating sleeve 12 of glass, glass-ceramic, ceramic or the like. Theinside diameter of sleeve 12 is very nearly the same as the outside diameter of blank 105 the spacing therebetween being preferably just sufficient to permit the blank to be easily inserted into the sleeve. One end of sleeve 12 may be fluted to facilitate insertion of blank 10. Blank 10 may consist of a substrate 14 having, for example, an electroconductive film 16 of tin and antimony oxides, nichrome, or the like deposited on the surface thereof. Substrate 14 is formed of a nonconductive material such as glass, ceramic or the like, and film 16 may be formed by any method known to those familiar with the art. A method of forming doped tin oxide films is disclosed in U.S. Pat. Nos. 2,564,706 and 2,564,707
issued in the name of John M. Mochel.
Spaced about lead 24 is a toroidally shaped fusible element or bead 26, of glass or the like material, having a coefficient of thermal expansion compatible with that of the encapsulating sleeve material and lead 24. While bead 26 is herein depicted as toroidally shaped, it will be obvious to those skilled in the art that this head may be either toroidal or shaped like a washer, that is, it may be flat. In any event, the outside diameterof bead 26 should be only slightly smaller than the inside diameter of the encapsulating sleeve 12.
Hermetic sealing materials for use'as the sleeve 12 and bead 26 are well known in the art, and no attempt will be made herein to list specific compositions for such materials. Since glass sleeves and beads have been extensively utilized to provide excellent hermetic seals for electrical components, this material is preferred for use in the present invention. A sodalime-glass is often used as the sleeve while a lead glass is used for the fusible bead. Typical glass compositions for use in. the
manufacture of hermetically sealed electrical compo- Thomas. Since alkali metals react with some electroconductive resistor films, the use of alkali-free encapsulation glasses may be preferred for use with such films, such glasses being disclosed in some of the aforementioned patents.
Whereas only one end of a resistor is shown in FIGS. 1 and 2, it is obvious that the same steps may be simul taneously or subsequently performed on the other end to form the completed resistor. It is preferred that the steps be simultaneously performed as hereinafter described. Resistor blank 10 is placed insleeve 12, and magnesium wafers 18 and conductive discs 20 are disposed at the ends thereof, beads 26 being disposed on leads 24 intermediate the ends thereof. Sufficient pressure is applied to lead wires 24 to keep conductive discs 20, magnesium wafers l8 and resistor blank 10 in intimate contact during the subsequent sealing process. An appropriate sealing flame is then applied to the juncture of sleeve 12 and bead 26 causing them to fuse together and form thejunction seal 28 shown in FIG. 2. Sleeve 12 extends beyond the end of blank 10 for a distancesufficlent to enable the formation of cavity' 22. Due to its proximity to the seal 28, the sealing-heat will melt and vaporize the magnesium metal, thereby forming a conductive film 30 which provides electrical contact between lead wire 24 and resistive film 16.
During the sealing operation heat generated by the flame is conducted through sleeve 12, bead 26, and
Magnesium may be disposed in the ends of the encapsulating sleeve in forms other than wafer 18 of FIG. 1. As shown in FIG. 5, wherein elements similar to those of FIG. 1 are indicated by primed reference numerals, a layer 48 of magnesium granules or powder may be disposed in one end of sleeve 12 which should be vertically disposed to prevent loss of magnesium. After one external lead is connected and one end of the resistor is sealed, the sleeve can be inverted and the second lead can be connected while the second end is sealed. FIGS. 6 and 7 show external leads having magnesium affixed thereto for ease of handling during the encapsulation process. As shown in FIG. 6, wherein elements similar to those of FIG. 1 are indicated by primed referencenumerals, a sheet 52 of magnesium foil is pierced by lead 54 to provide a combination that can be easily handled during the sealing and lead attachment process. As shown in FIG. 6, the end of lead 54 may directly contact the end of body 14. After the sealing process, a conductive cermet layer will extend from film 16 to lead 54 in a manner similar to that illustrated in FIG. 2, except that no conductive film will be disposed directly betweenlead 54 and substrate 14. The enlarged end 58 of external lead 60 of FIG. 7 is coated with a magnesium containing slurry or paste 62 which may consist of magnesium powder and a suitable vehicle such as water.
While the method of the present invention has been described in terms of resistance elements having electroconductive films, it is obvious that other types of resistorssuch as wire wound resistors may be employed equally as well. Also, other electrical components such as diodes or capacitive or inductive impedance elements can be hermetically sealed in accordance with the method of the present invention. In the case of a capacitor, the foil or plate ends may be provided with a conductive layer of the type shown in FIGS. 3 or 4.
Similarly, to encapsulate an inductive impedance, wire is wound about a form, and the wire ends and the form ends may be coated over with a conductive layer of the type shown in FIG. 4. Thereafter, the electrical connection of the terminal leads and hermetic sealing of the component is accomplished as hereinabove described in connection with the formation of encapsulated resistors.
I claim: 1. A method of forming an encapsulated impedance device comprising the steps of providing an impedance element having at least one electrical terminal at an end thereof, 7 providing a sleeve of fusible encapsulating material having at least one open end, disposing said sleeve about said impedance element so that said open end extends beyond and provides access to said terminal, disposing magnesium in said open end of said sleeve,
placing an end of an external lead into said open end of said sleeve,
disposing a fusible element about said lead intermediate the ends thereof, said fusible element having a coefficient of thermal expansion similar to that of said encapsulating sleeve material, and
applying heat, to that portion of the assembly so formed including said fusible element and the adjacent portion of said sleeve to cause said fusible element to form a hermetic seal with said lead and said sleeve, and to cause said magnesium to vaporize and form a conductive cermet layer extending between said electrical terminal and said lead.
2. A method in accordance with claim 1 further comprising the step of urging said end of said lead toward said impedance element during the step of applying heat.
3. A method in accordance with claim 1 wherein said fusible element is spaced from the end of said impe- 40 dance element so that the step of applying heat results in the formation of a cavity between said impedance element, sleeve and fusible element, and further causes said'magnesium to react with oxygen in said cavity to reduce the pressure therein.
4. A method of forming an encapsulated impedance device comprising the steps of providing an impedance element having electrical terminals at opposed ends thereof, disposing a sleeve of encapsulating material about said impedance element, the first and second open ends of said sleeve extending beyond the ends of said impedance element,
disposing magnesium in the first and-second ends of said sleeve,
inserting a first end of a first external first open end of said sleeve,
inserting a first end of a second external lead into said second end of said sleeve,
disposing a fusible element about each of said leads intermediate the ends thereof, said fusible elements having a coefficient of thermal expansion similar to that of said encapsulating sleeve material, and applying heat to those portions of the assembly so formed including said fusible elements and the adjacent ends of said sleeve to cause said fusible elements to form hermetic seals with their corresponding leads and with the corresponding ends of lead into said said, sleeve, and to cause said magnesium to vaporize and form a conductive cermet layer between said electrical terminals and said leads.
5. A method in accordance with claim 4 wherein said fusible elements are spaced from the ends of said impedance element so that the step of applying heat results in the formation of a cavity at each end of said impedance element between said impedance element, the adjacent end of said sleeve and said fusible element, and causes said magnesium to react with oxygen in said cavities to create a reduced pressure therein.
6. A method in accordance with claim 5 wherein said sleeve and said fusible elements are glass and where in the step of applying heat further causes said magnesium to react with the surfaces of said glass sleeve and fusible elements to reduce the same and form reaction products which constitute a part of said conductive cermet layer.
7. A method in accordance with claim 6 further comprising the steps of urging said first ends of said first and second leads toward said impedance element during the step of applying heat.
8. A method in accordance with claim 7 wherein the step of disposing magnesium in the open ends of said sleeve comprises disposing a magnesium wafer adjacent to each end of said impedance element.
9. A method of forming an encapsulated resistor comprising the steps of providing a resistor blank having a predetermined value of resistance and having electricalterminals at opposed ends thereof, disposing a sleeve of fusible encapsulating material about said resistor blank so that first and second open ends thereof extend beyond said blank, disposing a wafer of magnesium adjacent to each end of said resistor blank, providing first and second external leads, inserting a first end of said first lead into the first end of said sleeve, inserting the first end of said second lead into the second end of said sleeve,
disposing first and second fusible elements about said first and second'leads, respectively, intermediate the ends thereof, said fusible elements having a coefficient of thermal expansion similar to that of said encapsulating sleeve material, and
applying heat to those portions of the assembly so formed including said fusible elements and the adjacent ends of said sleeve to cause said fusible elements to form hermetic seals 'with their corresponding leads and with the corresponding ends of said sleeve, and to cause said magnesium to vaporize and form a conductive cermet layer between said electrical terminals and said leads.
l0. A'method in accordance with claim 9 wherein said sleeve and said fusible elements are glass and wherein said fusible elements are spaced from the ends of said impedance element so that the step of applying heat results in the formation of a cavity at each end of said blank between said blank,'the adjacent end of said sleeve and said fusible element and further causes said magnesium to react with oxygen in said cavities to create a reduced pressure therein and to react with the surfaces of said glass sleeve and fusible elements to reduce the same and form reaction products which constitute a part of said cermet layer.
11. A method in accordance with claim 10 wherein said first ends of said leads are provided with enlarged end portions, said method further comprising the step of urging the enlarged end portions of said first and second leads into engagement with the magnesium wafers adjacent thereto during the step of applying heat.
12. An encapsulated impedance device comprising an impedance element having at least one electrical terminal,
an external lead having an end thereof disposed adjacent to said electrical terminal,
a sleeve of encapsulating material disposed about said impedance element and said end of saidlead,
a fusible element disposed about said lead intermediate the ends thereof having a coefficient of thermal expansion compatible with that of said encapsulating sleeve material, said fusible element being fused to said lead and to the corresponding end of said sleeve, and
a conductive cermet layer disposed upon the inner surfaces of the end of said sleeve and said fusible element, said cermet layer including magnesium and magnesium oxide and providing an electrical connection between said electrical terminal and said lead..
13. An impedance element in accordance with claim 12 wherein a cavity is defined by the end of said impedance element and the inner surfaces of said fusible element and adjacent end of said sleeve, the pressure in said cavity being lower than ambient pressure.
14. An encapsulated impedance device in accordance with claim 13 wherein said sleeve andfusible element consist of glass and said cermet layer disposed upon said sleeve and fusible element includes reaction products that result from reduction of the surfaces of i a sleeve of encapsulating mate-rial disposed about said impedance element and said ends of said first and second leads,
first and second fusible elements disposed about said first and second leads, respectively, intermediate the ends thereof, the coefficient of thermal expansion of said fusible elements being compatible with that of said encapsulating sleeve material, each of said fusible elements being fused to its corresponding lead and to the corresponding end of said sleeve, and
.a conductive cermet layer disposed upon the inner surfaces of the ends of said sleeve and said fusible elements, said cermet layer including magnesium oxide and providing an electrical connection between said electrical terminals and associated I leads. I I 16. An encapsulated impedance device in accordance with claim 15 wherein cavities are defined by the ends of said impedance element and the inner surfaces of said fusible elements and adjacent ends of said sleeve, the pressure in said cavity being lower than ambient pressure.
17. An encapsulated impedance device in accordance with claim 16 wherein said sleeve and fusible elements consist of glass and said cermet layer disposed upon said sleeve and fusible elements includes reaction products that result from reduction of the surfaces of said glass sleeves and fusible elements by magnesium.
18. An encapsulated impedance device in accorenlarged end portions.
Claims (19)
1. A method of forming an encapsulated impedance device comprising the steps of providing an impedance element having at least one electrical terminal at an end thereof, providing a sleeve of fusible encapsulating material having at least one open end, disposing said sleeve about said impedance element so that said open end extends beyond and provides access to said terminal, disposing magnesium in said open end of said sleeve, placing an end of an external lead into said open end of said sleeve, disposing a fusible element about said lead intermediate the ends thereof, said fusible element having a coefficient of thermal expansion similar to that of said encapsulating sleeve material, and applying heat to that portion of the assembly so formed including said fusible element and the adjacent poRtion of said sleeve to cause said fusible element to form a hermetic seal with said lead and said sleeve, and to cause said magnesium to vaporize and form a conductive cermet layer extending between said electrical terminal and said lead.
2. A method in accordance with claim 1 further comprising the step of urging said end of said lead toward said impedance element during the step of applying heat.
3. A method in accordance with claim 1 wherein said fusible element is spaced from the end of said impedance element so that the step of applying heat results in the formation of a cavity between said impedance element, sleeve and fusible element, and further causes said magnesium to react with oxygen in said cavity to reduce the pressure therein.
4. A method of forming an encapsulated impedance device comprising the steps of providing an impedance element having electrical terminals at opposed ends thereof, disposing a sleeve of encapsulating material about said impedance element, the first and second open ends of said sleeve extending beyond the ends of said impedance element, disposing magnesium in the first and second ends of said sleeve, inserting a first end of a first external lead into said first open end of said sleeve, inserting a first end of a second external lead into said second end of said sleeve, disposing a fusible element about each of said leads intermediate the ends thereof, said fusible elements having a coefficient of thermal expansion similar to that of said encapsulating sleeve material, and applying heat to those portions of the assembly so formed including said fusible elements and the adjacent ends of said sleeve to cause said fusible elements to form hermetic seals with their corresponding leads and with the corresponding ends of said sleeve, and to cause said magnesium to vaporize and form a conductive cermet layer between said electrical terminals and said leads.
5. A method in accordance with claim 4 wherein said fusible elements are spaced from the ends of said impedance element so that the step of applying heat results in the formation of a cavity at each end of said impedance element between said impedance element, the adjacent end of said sleeve and said fusible element, and causes said magnesium to react with oxygen in said cavities to create a reduced pressure therein.
6. A method in accordance with claim 5 wherein said sleeve and said fusible elements are glass and where in the step of applying heat further causes said magnesium to react with the surfaces of said glass sleeve and fusible elements to reduce the same and form reaction products which constitute a part of said conductive cermet layer.
7. A method in accordance with claim 6 further comprising the steps of urging said first ends of said first and second leads toward said impedance element during the step of applying heat.
8. A method in accordance with claim 7 wherein the step of disposing magnesium in the open ends of said sleeve comprises disposing a magnesium wafer adjacent to each end of said impedance element.
9. A method of forming an encapsulated resistor comprising the steps of providing a resistor blank having a predetermined value of resistance and having electrical terminals at opposed ends thereof, disposing a sleeve of fusible encapsulating material about said resistor blank so that first and second open ends thereof extend beyond said blank, disposing a wafer of magnesium adjacent to each end of said resistor blank, providing first and second external leads, inserting a first end of said first lead into the first end of said sleeve, inserting the first end of said second lead into the second end of said sleeve, disposing first and second fusible elements about said first and second leads, respectively, intermediate the ends thereof, said fusible elements having a coefficient of thermal expansion similar to that of said encapsulating sleeve material, and applying heat to Those portions of the assembly so formed including said fusible elements and the adjacent ends of said sleeve to cause said fusible elements to form hermetic seals with their corresponding leads and with the corresponding ends of said sleeve, and to cause said magnesium to vaporize and form a conductive cermet layer between said electrical terminals and said leads.
10. A method in accordance with claim 9 wherein said sleeve and said fusible elements are glass and wherein said fusible elements are spaced from the ends of said impedance element so that the step of applying heat results in the formation of a cavity at each end of said blank between said blank, the adjacent end of said sleeve and said fusible element and further causes said magnesium to react with oxygen in said cavities to create a reduced pressure therein and to react with the surfaces of said glass sleeve and fusible elements to reduce the same and form reaction products which constitute a part of said cermet layer.
11. A method in accordance with claim 10 wherein said first ends of said leads are provided with enlarged end portions, said method further comprising the step of urging the enlarged end portions of said first and second leads into engagement with the magnesium wafers adjacent thereto during the step of applying heat.
12. An encapsulated impedance device comprising an impedance element having at least one electrical terminal, an external lead having an end thereof disposed adjacent to said electrical terminal, a sleeve of encapsulating material disposed about said impedance element and said end of said lead, a fusible element disposed about said lead intermediate the ends thereof having a coefficient of thermal expansion compatible with that of said encapsulating sleeve material, said fusible element being fused to said lead and to the corresponding end of said sleeve, and a conductive cermet layer disposed upon the inner surfaces of the end of said sleeve and said fusible element, said cermet layer including magnesium and magnesium oxide and providing an electrical connection between said electrical terminal and said lead.
13. An impedance element in accordance with claim 12 wherein a cavity is defined by the end of said impedance element and the inner surfaces of said fusible element and adjacent end of said sleeve, the pressure in said cavity being lower than ambient pressure.
14. An encapsulated impedance device in accordance with claim 13 wherein said sleeve and fusible element consist of glass and said cermet layer disposed upon said sleeve and fusible element includes reaction products that result from reduction of the surfaces of said glass sleeve and fusible element by magnesium.
15. An encapsulated impedance device comprising an impedance element having first and second electrical terminals at opposed ends thereof, a first external lead having an end thereof disposed adjacent to said first electrical terminal, a second external lead having an end thereof disposed adjacent to said second electrical terminal, a sleeve of encapsulating material disposed about said impedance element and said ends of said first and second leads, first and second fusible elements disposed about said first and second leads, respectively, intermediate the ends thereof, the coefficient of thermal expansion of said fusible elements being compatible with that of said encapsulating sleeve material, each of said fusible elements being fused to its corresponding lead and to the corresponding end of said sleeve, and a conductive cermet layer disposed upon the inner surfaces of the ends of said sleeve and said fusible elements, said cermet layer including magnesium oxide and providing an electrical connection between said electrical terminals and associated leads.
16. An encapsulated impedance device in accordance with claim 15 wherein cavities are defined by the ends of said impedance element and the inner surfaces of said fusible elements and Adjacent ends of said sleeve, the pressure in said cavity being lower than ambient pressure.
17. An encapsulated impedance device in accordance with claim 16 wherein said sleeve and fusible elements consist of glass and said cermet layer disposed upon said sleeve and fusible elements includes reaction products that result from reduction of the surfaces of said glass sleeves and fusible elements by magnesium.
18. An encapsulated impedance device in accordance with claim 17 wherein said impedance element is a resistor blank having a predetermined value of resistance.
19. An encapsulated impedance device in accordance with claim 18 wherein the ends of said first and second external leads that are disposed adjacent to said first and second electrical terminals are provided with enlarged end portions.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US00358014A US3810068A (en) | 1973-05-07 | 1973-05-07 | Impedance element with magnesium reaction terminal contact and method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US00358014A US3810068A (en) | 1973-05-07 | 1973-05-07 | Impedance element with magnesium reaction terminal contact and method |
Publications (1)
Publication Number | Publication Date |
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US3810068A true US3810068A (en) | 1974-05-07 |
Family
ID=23407948
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US00358014A Expired - Lifetime US3810068A (en) | 1973-05-07 | 1973-05-07 | Impedance element with magnesium reaction terminal contact and method |
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US (1) | US3810068A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2808950A1 (en) * | 1977-03-03 | 1978-09-07 | Philips Corp | PROCESS FOR MANUFACTURING A HERMETICALLY SEALED ELECTRICAL OR ELECTRONIC COMPONENT |
US4117589A (en) * | 1975-09-25 | 1978-10-03 | North American Philips Corporation | Method of manufacturing a hermetically sealed electronic component |
US4130722A (en) * | 1977-01-10 | 1978-12-19 | Globe-Union Inc. | Thick-film circuit module including a monolithic ceramic cross-over device |
US4189083A (en) * | 1978-06-15 | 1980-02-19 | Motorola, Inc. | Low temperature and low cost assembly process for nonlinear resistors |
US5664320A (en) * | 1994-04-13 | 1997-09-09 | Cooper Industries | Method of making a circuit protector |
US6333209B1 (en) | 1999-04-29 | 2001-12-25 | International Business Machines Corporation | One step method for curing and joining BGA solder balls |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1991774A (en) * | 1928-11-23 | 1935-02-19 | Old Colony Trust Company | Photoelectric tube |
US2802127A (en) * | 1954-02-03 | 1957-08-06 | Dobischek Dietrich | Dynode coating |
US3307134A (en) * | 1959-12-14 | 1967-02-28 | Corning Glass Works | Encapsulated impedance element |
-
1973
- 1973-05-07 US US00358014A patent/US3810068A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1991774A (en) * | 1928-11-23 | 1935-02-19 | Old Colony Trust Company | Photoelectric tube |
US2802127A (en) * | 1954-02-03 | 1957-08-06 | Dobischek Dietrich | Dynode coating |
US3307134A (en) * | 1959-12-14 | 1967-02-28 | Corning Glass Works | Encapsulated impedance element |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4117589A (en) * | 1975-09-25 | 1978-10-03 | North American Philips Corporation | Method of manufacturing a hermetically sealed electronic component |
US4130722A (en) * | 1977-01-10 | 1978-12-19 | Globe-Union Inc. | Thick-film circuit module including a monolithic ceramic cross-over device |
DE2808950A1 (en) * | 1977-03-03 | 1978-09-07 | Philips Corp | PROCESS FOR MANUFACTURING A HERMETICALLY SEALED ELECTRICAL OR ELECTRONIC COMPONENT |
FR2382825A1 (en) * | 1977-03-03 | 1978-09-29 | Philips Corp | Hermetically sealed electric module e.g. diode or capacitor - with fusible cup enclosing ceramic core with high melting metal discs and solder parisons |
US4189083A (en) * | 1978-06-15 | 1980-02-19 | Motorola, Inc. | Low temperature and low cost assembly process for nonlinear resistors |
US5664320A (en) * | 1994-04-13 | 1997-09-09 | Cooper Industries | Method of making a circuit protector |
US6333209B1 (en) | 1999-04-29 | 2001-12-25 | International Business Machines Corporation | One step method for curing and joining BGA solder balls |
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