FR2623341A1 - ELECTRICAL CONTACT, IN PARTICULAR FOR LAMP, AND METHOD FOR PRODUCING SAME - Google Patents

Abstract

An electrical contact having improved abrasion and thermal characteristics is disclosed. It consists of a conductive base material intended to ensure mechanical resistance at the temperatures concerned, and of a layer of gold carried by the base material so that at least part of the gold diffuses into this material. basic. This can in particular be nickel. Area of application: lamps for operating theaters, etc.

Description

The invention relates generally to electrical contacts, and

more particularly

  electrical contacts used in lamps.

  Very often, lamps, for example surgical lights, are implemented in a posi-

  returned, which can lead to excessive temperatures.

  seated at the lamp-pin contact interface / -l3 '' - e - I-a-c> "l '. 1, and / or erosion of the pins and bush Corrosive films formed of residues

  organic matter suspended in the air,

  tent of thickness until the drilling potential

  or breakdown of the film exceeds the applied potential.

  Increases in the electrical resistance of these films raise the temperature at the point of contact because of the heat produced by the contact resistance and heat from the lamp filament. erosion

  is mainly due to low-voltage breaking arcs.

  Usually, lamps with

  both nickel-plated brass pins with contacts of

  sockets in silver nickel or silver brass. The dream-

  The silver is removed by wear when the lamp is inserted, replaced, or arcing occurs when the applied potential and the resulting current eliminate it. Contact films.Test results have shown that there are

  at the pin interface of the lamp / socket

  sufficient contacts to soften the pins

brass of the lamp.

  The film formation characteristics vary with the type of metal used. The metals were grouped according to their piercing tension of the film after prolonged exposure to the environment. Nickel and

  copper (or brass) have film resistors

  to reach a megohm and film piercing potentials of 10 to 100 volts, which is often greater than the voltage applied to surgical lamps. Gold,

  silver and rhodium have film resistors

  less than 1 ohm, 100 ohms, and 100 ohms,

  respectively, and the drilling voltages of the film less

  0.1 volts, 1 to 10 volts and 1 to 10 volts, respectively.

  tively. These piercing voltages are usually

  less than the applied voltage for china lamps

  rurgicales. The growth rate of the film increases with temperature, humidity, the degree of organic contamination of the air in the vicinity of the contacts and the degree of

  priming arcs to contacts. The temperatures at

  tacts of the socket can be between 95 and

  315 C in surgical lighting fixtures

  tungsten-halogen lamps. Tests to cool the lamp environment can disrupt the tungsten-halogen cycle, causing degradation

  the performance of the lamp and its life. This-

  during, a decrease in the temperature and degree of arcing of the lamp / socket pin interface

  should lower the -types of tailings formation

  and film training. In the app to

  surgical lighting apparatus, the requirements for

  both on the delamp / socket pin contact material

  include an electrical conductivity and a conductivity

  high thermal stability, ability to withstand 315 C operating temperatures,

  high corrosion resistance and high resistance to abrasion.

  if we. The materials currently available for lamp / socket pin contacts do not meet all these requirements. It has appeared that the failure rates of lampholders in certain types

  surgical lighting devices are unacceptable-

  the market and services in the field. The frequency of replacements of the bushing, or bushing assembly, in the field usually amounts on average to one replacement per nine-month period. The failure mode of the bushing is mainly due to corrosion and / or erosion

  contacts of the socket, which cuts the electrical circuit

  cudgel. There is therefore a need for contact sets for lamp / socket pins that satisfy

  all the criteria mentioned above.

  The invention relates to an improved electrical contact having improved characteristics in

  regarding abrasion and resistance to heat.

  The contact is made of a basic conductive material which provides the mechanical strength at the relevant temperature. When the base material is nickel, a layer of gold may be deposited on the nickel and treated so that at least a portion of the gold diffuses into the nickel. When the base material is not nickel, it must first be coated with a layer of nickel. Then the nickel layer is coated with a layer of gold. The gold layer is treated so that

  at least some of the gold diffuses into the nickel.

  Electrical contacts made according to

  in accordance with the present invention exhibit a better

  resistance to abrasion compared to

  both to form gold coatings while retaining

  high resistance to corrosion and high conductivity

  thermal and electrical potentials. These and other benefits

  interests of the invention will emerge from the description

detailed below.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limiting example and in which: FIG. 1 is a partial section of a

  lamp base comprising contacts made in accordance

  the invention, inserted in a lighting unit; Figure 2 is a sectional elevational view of the lamp base shown in Figure 1; Fig. 3 is an enlarged view of the large and small heat radiators, and Fig. 4 is an end view looking inwardly of the lamp base shown in Fig. 2. It has been determined that nickel coated with gold has very favorable characteristics suitable for the interface of the lamp / socket pin contacts of a surgical lighting apparatus, with the exception of the low resistance to abrasion of gold. However, it has been found that if gold is applied to the nickel so as to diffuse into the nickel surface, the abrasion resistance of the surface is substantially improved.

  same time that the excellent conducti

  electrical and thermal stability and resistance to corrosion

  gold. The nickel base material provides the required mechanical strength to withstand the temperatures at the interface of the pin contacts

lamp / socket.

  A method for depositing a layer of gold on a nickel base, which gold layer is then annealed so that the gold surface layer is converted into a gold and nickel alloy, is available in the

  trade with Inco Alloys International.

  This firm uses this process to produce a new material to hit, designated by the Trade Mark "NiGOLD". The process for producing this material (hereinafter referred to as the "NiGOLD process") was developed as a result of the desire to have such a striking material having the brilliance of gold but an abrasion resistance. much higher. The present Applicant is the

  first to recognize the benefits of using

  use of "N4iGOLD" type material in electrical applications. In such applications, not only the contacts made in the "NiGOLD" type

  good abrasion resistance and good conductivity

  electric power, but they also present unexpectedly

  stretched with good thermal properties. This De-

  wandering is the first to recognize these thermal properties.

  Electrical contacts made according to

  The invention can be used in many applications. An electrical contact made in accordance with the invention will be described in the application to a surgical lighting apparatus 10 illustrated in FIG. 1. It is not desired to limit the present invention to the apparatus

  In contrast, there is a need for

  electrical contacts in accordance with the invention can be used in many applications requiring

  electrical contacts having good resistance to abrasion

  high thermal and electrical conductivity, good resistance to film formation, and capable of

  to operate at high temperatures.

  The lighting apparatus 10 comprises a base

  12 of lamp carrying a lamp 14 as shown on the

  1. Lighting apparatus 10 has an opening

  16 in which the lamp 14 and the base 12 are inserted.

  As shown in Figures 2 and 4, the base 12 includes

  a lampholder 18 having a first electrical contact

  20 and a second electrical contact 22. The first and second electrical contacts 20 and 22 are connected to a source of electrical energy via wires

24 and 26, respectively.

  The lamp base 12 comprises a cap 28,

  that can be better seen in Figures 1 and 2.

  28 skin wears a heat sink 30 mount like

  shown in Figure 2. Mount 30 carries a large gap

  thermal director 32. A heat seal 34 made of

  any suitable is interposed between the large radia-

  The large radiator 32 carries a small heat radiator 36. The small heat radiator 36 and the large radiator 32 are configured to carry the lamp socket 18 as shown on FIG.

Figure 2.

  Two stands 12 of lamps of the type described herein have been equipped with electrical contacts 20 and 22 made in accordance with the invention for testing purposes. Contacts

  were made of NiGOLD material, that is,

  that Nickel contacts were sent to Inco Alloys International for submission to the

NiGOLD process.

  Referring to Figure 3, we used a

  RTV resin (room temperature vulcanizing), conductive

  heat seal, to hermetically seal all contact surfaces between socket 18 of

  lamp, the large radiator 32 and the small radiator

  Thermal Dimer 36. No RTV resin was placed on the back surface of the lamp socket 18 or in the contact cavities. To evacuate all the air from the cavity, the RTV resin was applied on both sides of the connections 37 between contact tabs and crimp terminals, which is partially seen in FIG. a bushing terminal insulator 38, as seen in FIGS. 2 and 3, on the wires of the bushing assembly 18. The terminal insulator 38 was pushed against the body of the bushing 18 of the bushing.

  repress excess RTV resin that has been removed.

  Then RTV resin was used to cover the outer face of the bushing insulator 38. A third lamp base 12 was tested with a conventional lamp socket of the "Buhl QEW-0" type having

  conventional nickel electrical contacts.

  The test was conducted at a power of 235 watts and a current of 11 amps. These high level operating parameters were chosen to accelerate the lamp aging test. The voltage drops between the electrical contacts 20, 22 of the three lamp bases, over a period of 391 hours, are grouped together

in Table 1.

8 -2623341

Table 1

  contact 20 contact 22 hours VOltS, nol VotS $, re2 V '"sen3 Vol tc., nol Vol: S, n 2 Volts, n 3

  0.020 0.025 0.056 0.011 0.011 0.095

  18 0.019 0; 027 0,) 83 0; 011 0.011 - 0.143

0.021 0.039 0.141 0.014 0.014 0.083

  72 0.020 0, C44 0152 0.013 0,) 014 0.098

  83 0.021 0.04) 0.150 0.0J4 0.015 0.240

0J021 0.046 0.171 0.014 0.016 0.207

  101 0 022 0.048 qril (aqe 1 0.014 indefinite 2 rilaqe 1083 0.022 1 034 0014 indfinite 2 undefined

119 0.023 0.053 0.014 0> 016

126 0 024 0.044 0.0] 4 0.018

137 0.024 0.049 0.014 0.018

144 0, 025 0.044 0, Q4 0 018

191 0.046 0.054 0.015 0 021

198 0> 00 0060 0015 0.021

2C9 Ot082 0 091 0 015 0.022

216 0.067 0 086 0.015 0 022

227 0.101 01049 0.018 0.022

234 0 064 0.133 0019 0020

  245 0, 077 00225 0,020 defined 252 0e168 0,127 0p0201 0,021 263 181,028 0,021 indefire noon the 2 lamps off 10:00 a.m. the 2 lamps alumees

272 0O011 0X212 0.006 0) 026

283 0X154 0; 058 0> 006 0026

290 0.196 0.122 0.023 0.026

  301 0.081 0o, 070 0023 0.026 308 0.095 0j122 0023 0X026

319 0) 177 0.120 0024 0026

326 0.222 0.081 0.023 0.026

337 0285 0/117 o, 024 0.026

344 0.216 0.120 0.025 OO26

  1'3n grinding 0> 058 gri ((aoe 0027 The grid was a roasting contacts contacts

the socket.

  The term "indefinite" indicates that no other

a reading.

  3 Battery replaced in the test apparatus.

4 The grill was on the lamp.

  In addition to voltage measurements, we performed

  the temperature measurements on the contacts 20, 22,

  which measurements are given in Table 2, and on a handle 40 (see FIG. 1), the heat radiator 32 and the cap 28, these measurements being grouped together in FIG.

Table 3.

2623341

Table 2

  Contact 20 (OC) Contact 22 (OC) Hours # 1 # 2 # 3 # 1 # 2 # 3

11 195 179 222 200 195 235

18,193,177 228,199,193 238

196 180 238 203 196 253

O10 72 195 180 237 257 199 251

83 196 180 243 203 199 260

9U 195 180 274 257 199 288

  101 196 182 toasting 203 200 toasting

1082 176 145 182 180

119,177 145 182 182 182

126,177 166 182 182 182

137,177 166 182 182 182

144,177 166,182 182 182

191 179 168 184 184

198,177 166,182 184

209 182 170 184 187

216 179 170 182 184

227 182 184 176 187

234 179 179 182 187

245 181 188 184 192

252 188 175 187 187

263 192 200 187 193

  noon the 2 lamps off 10:00 a.m. The 2 lamps lit

272 182 181 184 188

2623341

283 188 170 187 187

290 190 175 187 187

301 184 176 187 188

308 182 177 184 188

319 190 177 188 188

326 193 175 187 188

337 195,177 184,188

O10 344 195 177 187 188

  391 toasting3 176 toasting3 187 Toasting was a toasting

the socket.

  2 Battery replaced in the test apparatus.

  The roasting was a roasting lamp.

12 2623341

Table 3

  Handle 40 (C) Heat radiator 32 (C) Hat 28 (C) Hours n0 1 n 2 n 3 n I n 2 n 3 n 1 n 2 n 3 1il 83 77 82 165 152 176 82 78.78

18 83 72 81 160 152 177 82 78 78

87 76 81 166 153 179 83 78 78

72 83 77 81 163 153 177 82 81 81

  O10 83 87 76 82 166 155 179 83 81 81

83 72 87 165 155 196 83 81 83

  101 87 78 netting1 165 155 netting1 83 82 netting

1082 78 71 148 141 77 76

119 81 77 150 141 78 76

126 78 78 148 143 77 76

137 78 77 148 143 77 76

144 78 78 148 143 77 76

191 81 78 150 143 78 76

198 77 77 148 143 77 76

209 78 72 150 143 78 76

216 78 78 148 143 77 76

227 78 78 148 144 77 76

234 76 72 148 144 76 72

245 78 69 150 146 77 76

252 78 69 150 144 77 76

263 81 83 150 148 77 76

  noon the 2 lamps off 10:00 a.m. the 2 lamps on

272 77 82 150 144 77 76

13 2623341

283 78 82 152 144 77 76

290 78 82 150 144 77 76

301 78 82 152 146 77 76

308 78 82 150 144 77 76

319 78 82 152 146 77 76

326 78 82 152 144 77 76

337 78 83 150 146 77 76

1 0 344 77 82 150 146 77 76

  391 wire netting3 81 wire netting3 143 griLLage3 72 1 The wire netting was a wire mesh

the socket.

  2 Battery replaced in the test apparatus.

  2 The roasting was a roasting lamp.

14 2623341

  The lamp bases 1 and 2 having electrical contacts made in accordance with the invention have characteristics superior to those of the number 3 lamp base having nickel contacts according to the prior art. For example, at 90 hours, the voltage drop across the contact 20 of the number lamp base

  3 was 0.171 volts and the temperature was 274 C.

  Apparently, a film was formed on the contact and the value of the film strength caused an increased voltage drop across the contact as well as a significant rise in contact temperature. Between 90 hours and 101 hours of operation, the contacts of the base of

Lamp No. 3 grilled.

  On the other hand, at 90 hours of operation, the voltage drop across the contact of the No. 1 lamp socket was 0.021 volts and it was 0.046 volts across the contact of the No. 2 lamp socket.

  Table 2 shows that the temperatures were respectively

  195 and 180 C. Apparently, the formation of a film on the contacts made according to the invention was

  very low after 90 hours of operation and the

  tacts showed virtually no temperature rise. At 263 hours of operation, it can be seen that the voltage drop across contact 20 of the No. 2 lamp base is 0.428 volts. With reference to Table 2, even with such a high voltage drop,

  the temperature rose only slightly, to 200 C.

  It can thus be seen that as tests progressed and the voltage drop across

  increased contact, the temperatures never reached

  dyes the level of 204 C that was reached early on the No. 3 lamp base with nickel contacts, and that it has never safely reached the level of 2600C at which the lamp base came

2623341

  number 3 shortly before the contacts burn. The data grouped in Tables 1, 2 and 3 clearly show that NiGOLD process contacts have superior qualities, even when the voltage drop across the contact has increased, which would indicate the formation of a film. temperatures have remained within reasonable limits.These unexpected thermal characteristics, considered at the same time as the ability of

  abrasion-resistant contacts, their good characteristics

  electrical resistance and their resistance to film formation, make these contacts highly desirable in

* applications o such features are required.

  Finally, we can see that even after 391 hours of operation at high power levels, the

  contacts according to the invention were still capable of

  and did not approach the high temperatures

  ves reached by the number 3 lamp base shortly before

  that the contacts burn. The ability to drive effectively

  heat and resist the formation of films

  indicates that contacts made in accordance with the

  have an adverse effect on lamp life and should allow lamps to

  higher current levels.

  The exact mechanism by which gold is de-

  placed on the nickel to form an electrical contact is

  not considered to be an element of the invention.

  Spray deposition, vapor phase deposition, electro-

  testimony, etc., could be used in accordance with the

  stances. It is also envisaged to be able to use other materials, for example brass or other electrically conductive materials having a high mechanical strength at the temperature concerned, as material

  basic. Under these conditions, the basic material is

  in the desired configuration for the contact and coated with nickel. Methods for depositing nickel

16 2623341

  on the base material, other than an electrolytic deposit, may be used. Then the contact is submitted to the NiGOLD process. However, the material of the type "NiGOLD" is applied so as to be carried by the base material or, if the contact itself is made in the matter of

  NiGOLD type; it seems that such an electrical contact pos-

  sede properties that were impossible to obtain

until now.

  It goes without saying that many modifications can be made to the electrical contact described and

  shown without departing from the scope of the invention.

17 2623341

Claims (6)

  1. Electrical contact with characteristics   improved abrasion and thermal properties, characterized in that it comprises a nickel base element for ensuring the mechanical strength and a gold layer pored by the base element so that at least a part   diffused gold in the basic element.   2. Electrical contact with characteristics   improved abrasion and thermal properties, characterized   in that it is made of a material of the "NiGOLD" type.   3. Electrical contact with characteristics   improved abrasion and thermal properties, characterized in that it comprises a conductive base element intended to ensure the mechanical strength, a nickel layer carried by the base element and a layer of gold carried by the nickel layer. so that at least a part of gold diffuses into nickel.   4. Electrical contact with characteristics   improved abrasion and thermal properties, characterized in that it comprises a base element intended to ensure the mechanical strength and a layer of material of the type   "NiGOLD" carried by the basic element.   5. A method of producing an electrical contact   characterized in that it comprises forming a base material in the desired form of electric contact, depositing a gold layer on the base material and treating the gold layer to cause diffusion of at least   part of this layer in the base material.   6. Process according to claim 5, characterized   in that it further comprises depositing a layer of nickel on the base material, the gold layer being deposited on the nickel layer and the treatment of the gold layer causing the diffusion of at least one part   of this layer of gold in nickel.