CS243452B2 - Flat electric resistor with accuracy and adjustable ohmic value and method of this ohmic value adjustment - Google Patents

Abstract

1. A high-precision flat electric resistor having an adjustable resistance value and comprising a sheet of metal or metal alloy deposited on or bonded to a support comprising several electric, resistive, sinuous and interconnectable circuits, each of them being constituted by a series of electrical resistance filaments separated by grooves, some of the said resistive circuits being short-circuited by conductive strips of the metal or metal alloy of the sheet, these circuits being interconnectable by means of cut-out portions made in the conductive strips, the resistance value of a resistor having n electric circuits interconnected in serie being RTn and that of a resistor having n-1 electric circuits interconnected in series being RTn-1, characterized in that the ratio DELTA R = RTn - RTn-1 to the resistance value RTn-1 follows the relation : DELTA R/RTn-1 = 1.3...2n-1/2.4...2n K**2n where K is an adjustable numerical coefficient having a value smaller than 1.

Description

(54) Surface electrical resistance with high accuracy and adjustable ohmic value, and how to adjust this ohmic value

It is a surface electrical resistance consisting of a foil of metal or alloy deposited or glued to the carrier, the resistance path forming a meander circuit and a method of adjusting it to a prescribed value. The Oipor is designed to include a set of resistors shorted by conductive bands grouped into rectangular blocks. When adjusting the ohmic value, the cut-outs in the conductive strips are formed in a certain way, whereby the total ohmic value gradually increases up to the value determined.

243452,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface electrical resistor with high accuracy and adjustable ohmic value and to a method for adjusting this ohmic value.

High-precision electrical resistors are known which are produced by etching electrolytically by treating it with ionic bombardment of a metal or metal alloy foil to form a plurality of electric fibers separated by grooves or slits.

These methods make it possible to produce resistive circuits of meander or other undulating shape and ^large length. SlektricM from ^p orová vláirna formed by etching the metal foil Neto sliUnové. They have a thickness not exceeding several µm, so that these resistors have a very high ohmic value per unit area.

After series production, these resistors are to be set to an exact ohmic value, which is often greater than 50 to 150% of the original ohmic value.

In the known methods, this value is adjusted so that cuts are used to connect a predetermined number of these fibers between the edge of the resistor and the grooves separated by one of the wild resistive electric fibers to increase the ohmic value. This process of adjusting the resistance by forming slices is very demanding. This operation must be carried out under a microscope by scraping, by a jet of sand or by laser. Furthermore, this operation is very lengthy, since it is often necessary to produce a very large number of cuts, since there is a large number of electrical resistive fibers in each individual resistance. For example, if the ohmic value of the resistor, which has an initial value of 23 k?

It is an object of the present invention to provide a surface electrical resistance such that its ohmic value can be adjusted in a more convenient, faster and simpler manner than the prior art resistors.

The object of the invention is a surface electrical resistance, which consists of a metal or alloy foil which is deposited or adhered to a support and consists of a set of electric resistance fibers separated by gaps so as to form a meander resistor. The resistor comprises a plurality of electrical resistive circuits that are shorted by conductive strips of metal or foil alloy.

According to the invention, this area electrical resistance is characterized in that the ratio of the increment AR of the ohmic value RTn when connected to a series of n coupled resistance circuits and the ohmic value RTn-1 of the resistance when connected to a series of n-1 coupled circuits

RTn-1 ⁿ _n where U _n is the nth member of the absolutely convergent series in the Cauchy criterion, and Δ R = RTn - RTn-1.

In order to adjust the resulting ohmic value of the resistor, cutouts are formed in the film which are used to connect in series with the other circuit. resistive electrical circuit or resistive electrical circuit whose ohmic value corresponds to the set ohmic value required for this resistor.

It has been found that when the AR increment satisfies the above-mentioned relationship, the number of cut-outs to be drawn in the film to adjust the ohmic resistance of the resistor can be substantially mentioned.

According to a preferred embodiment of the invention, the relationship R 1 applies

1.3.оП-1

RTn-1

2.4,

2η where Κ is nunerický adjustable factor smaller than the first Viyiález also relates very precise electrical resistance, a metal foil RTE them sHtiny ^h of metal is deposited or ^p řieepena to divulge the S ^ l ^ CH ^ I1 ^ <^: The thermal conductivity is generally equal to or greater than the thermal conductivity of the alumina, thus avoiding the formation of an excessive temperature gradient between the interconnected resistive portions of the circuit and those that are still short-circuited.

The present invention further provides a method for adjusting the ohmic value of the surface electrical resistance.

According to this method, cutouts are formed in the conductive strips that short-circuit the associated electrical resistance circuits. According to the invention, such a cut-out is first formed in a conductive strip corresponding to one associated circuit so that the increment of the ohmic value is as close as possible. the desired ohmic value, then proceed in the set-up by sequentially connecting the other associated circuitry to produce ohmic value increments that change gradually.

In this way, a single cut-out is made for one mating circuit, so that the maximum number of cut-outs does not exceed the number of mating circuits. Since each composite circuit is generally made up of a plurality of parallel resistive fibers which extend over a relatively large area, the cut-out does not require as much precision as the prior art.

According to the invention, it is furthermore advantageous to provide in the strips simultaneously with the various resistive electrical circuits a numerical mark and a slot which extends through the numerical numeral and the corresponding associated resistive circuit, this cut being performed between the film side and said numerical resistance. sign. These numerals ^p odstaině usnadňučí znavní associated ^ otorodů, ktam the MS oppoit ^ i ^, 'and drilling of the cutouts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of the electrical resistor of the present invention; and FIG. 2 is an enlarged view of a portion of the resistor of FIG. 1 showing an electrical associated circuit connected to the remainder of the resistor;

1 and 2, there is shown an electrical sheet resistor made of a square foil 10, which is of metal alloy and has a thickness of? 1 / cm c / µm, and is, for example, of a nickel-chsam alloy. The electrical resistive circuit of this resistor is manufactured in a manner known per se, preferably electrically by etching or ionic bombardment through a window mask, which defines the contour of the formed electrical resistance on the film 10.

the TO film is deposited or adhered to an electrically insulating support (not shown) having an electrically insulating support. thermal conductivity equal to or greater than 96% pure aluminum oxide.

For the sake of clarity, the electrical resistive filaments 11 are shown in FIG. 1 between straight parallel lines which show the gaps 12 of the resistor. The actual representation of a part of the resistance circuit is shown in FIG. 2.

As can be seen in FIG. 1, the resistor consists of a plurality of parallel resistive fibers which form a meander electric circuit of great length and consequently a high ohmic value per unit area.

The film 10 comprises a set of coupled resistor circuits A ^, Ag, A ^ j,, Bg, B ^, Cp Cg ... θ, Dp Dg ... D ^, whose increment Δ R of internal ohmic values satisfies the relation

Δ R

-------- = ° n RTN-1 where U _n is the nth member of the absolutely convergent series in terms of the Cauchy criterion, aAR = RTn -RTn-1, where RTn is the ohmic value of n coupled resistor circuits, and RTn -1 is the ohmic value of n-1 coupled resistor circuits.

It can be seen from FIG. 1 that the composite circuit Aj has a larger number of resistive fibers 11 than the composite circuit Ag, which in turn has a plurality of resistor fibers 11 than the other composite circuits A1, B1, Bg etc.

The convergent series can be shaped

1.3 R 1.3 ··· 2n — 1 у 2n

RTn-1 2.4 ··· 2n where К is an adjustable numerical coefficient less than 1. This convergent series can be a geometric series.

As can further be seen from FIG. 1, in the manufacture of the resistors of the invention, the film 10 and each of the associated circuits A ....... Bp ..., Cp ..., are left between the sides A, V, C, D of the film 10, D-conductive strips 13, 14, 15, 16, 17, 18 which are short-circuited these combined circuits relative to the remainder resistance · Consequently, the resistance produced by this method the initial value of the resistance R T _Q, which is formed by the ohmic value of the resistive electrical filaments 11 which does not belong to the associated circuits A | ..., Β ^, · · ·, C _] , · · ·, Dj ·

To set the ohmic value of the resistor to the desired value, start by connecting the earliest mating circuit Ap ..., Bp ..., C _f or Dp that has the ohmic value closest to the desired value, and then adjust it further by connecting individual coupled circuits having decreasingly lower and lower ohmic values. To do this, a cut-out 19 (FIG. 2) is formed in the conductive strips 13, 14, 15, 16, 17 or 18, which lies between the side A, B, C or D of the film 10 and the corresponding associated circuit. , for example, the cut-out 19, is formed in a manner known per se, for example by scribing with a tip, a jet of sand or a laser.

In order to set the resistance over a sufficiently large range of ohmic values, a coefficient M, generally equal to the ratio RTn / RT _Q (where RTn is the ohmic value formed by the coupling of all the coupled circuits) close to 2 is generally chosen.

1 and 2, they are formed in the conductive strips 13 to 18 together with the various associated circuits Ap ..., Bp., .., C ^ ..... Dp ... of the numeral marks 1, 2 3, 9, and slot 20 (FIG. 2) extending between these numbers 1 to 9 and the associated associated circuit ky

To set the resistance to the desired value, it is then sufficient to mark the numerical mark of the associated circuit circuit Ap. ·., Bp ···, Cp ··., Dp · .. to be connected, then make a cutout 19 according to Fig. 2 between side A , D, C or D of the film 10 and the numeral of the corresponding mating circuit.

In the embodiment of FIG. 1, the electrical mating circuits A _p ..., B _p ... »D, ... are grouped into four separate rectangular blocks 21, 22, 23, 24, each of which is disposed about an This embodiment greatly facilitates the labeling of the individual circuit circuits.

To illustrate the invention, there will be given as many numerical examples.

Example I

This non-limiting example illustrates the intricacies according to which the resistance is adjusted by the method of the invention.

This resistance is characterized by a number of set points equal to 23 and a coefficient M equal to 2. This salt M is the ratio of the resistance value when they are. all points /, and o are set to the initial resistance value. According to the invention, the following normality is followed:

· 1.3 ·. · 0η-1

RRTh-1 2.4..2 ^ o

For RT _Q = 15 kftplati follows! table:

K ^{2 O, e} k d k = ^0, 82nd

Table I

Setting point AR / RTn-1 AR / RT ₀ AR (ohm) A _t 1 0.336 0.336 5 040 * 2 2 0.169 0.226 3 390 A ³ 3 0,095 0.143 2 145 B, 4 0.56 0,090 1 350 b ₂ 5 0,034 0,056 840 B ₃ 6 0,021 0,035 525 ^C 1 7 0.013 0,022 330 ° 2 8 0.0082 0.014 210 ^C 3 9 0.0052 0.009 135 «4 10 0,0033 0.006 90 ^C 5 1 i 0,0021 0.0036 54 C ₆ 12 0,0014 0,0024 36 C7 13 0.0009 0,0016 24 c8 14 0.0006 0,0010 15 Dec D, 15 Dec 0.0004 0.0007 10.5 ^D 2 16 0.00024 0.00042 6.3 ^D 3 17 0.00016 0.00028 4.2 »4 18 0.00010 0.00017 2.55 (B) 19 Dec 0.00007 0.00012 1.80 »6 20 May 0.000045 0.000079 1,185 »7 21 0.000029 0.000051 0.765 »8 22 · 0.000019 0.000033 0.495 D ⁹ 23 0.000012 0.000021 0.315

When all the resistors are connected, that is, when twenty-three slots 19 have been formed, the mmx wavelength set resistance is 14,212 ohms - 15,000 ohms (initial value) = = 29,212.11 ohms, ie ^^ ι ^^ π ^ ΟΙ ^ ζ ^ ί equal to 1,9474.

Example II

The resistance according to this example has an initial ohmic value RT_ equal to 15. This value must be set to 25,000 ohms ♦ 0.1%. Thus, the initial value should be increased by 66.51 to 66.83% to lie within the tolerance range of - 0.1%.

For this purpose, the circuit or circuits whose ohmic value is the closest to the value to be produced is selected first. In this case, points A] and Ag, kerérna eats the weight between 33.6% and 22.6%. It creates a cut-out of 19 dMee Dps in a manner. The cutout for B ₁ is 9%, the cutout for Cg is 1.4%, and the cutout is 0.07%.

This gives 66.67%. This result was therefore achieved by making five cut-outs 19 according to the obia. 2.

If it was necessary to further adjust the ohmic value of the resistor, further cut-outs would have to be made in order to connect additional coupled resistor circuits, the ohmic value of which is constantly smaller.

Example III (comparative)

In the case of a resistor reacted by the classical setting method, the resistor having an initial ohmic value equal to that of Example II, a total of 27 slots are provided to produce a resulting resistance of 25 kilos - 1%. .

It is self-evident that the invention is not limited to the examples described and that it can be varied in various ways. For example, the resistor can be adjusted by engaging or in a known manner

To the bridge of the bridge and with a digital voltmeter. It is also possible to use an automatic computer in which the ohmic values of each of the associated circuit circuits are recorded. the image of the resistance is observed by a binocular, or controlled by a sliding table XY, which carries a known automatic cutter, for example a sand jet or laser, and which is controlled by a digital computer. This is due to the fact that the numbers 1, 2, 3 ... 9 of the associated circuits are not very numerous - and at the same time they are large enough so that there are no mechanical problems in guiding the cutting device.

Due to the existence of the numbers 1 to 9 and the conductive strips 13 to 18 that are between these numbers 1 to 9 and the sides A, B, C or D of the resistor, adjusting the resistance can be done by simply scraping between the respective number and the adjacent edge.

Claims (5)

SUBJECT OF THE INVENTION A high-precision, resistivity-adjustable surface electrical resistance consisting of a metal or alloy foil deposited or supported on a support and comprising a spaced-apart array of resistive electrical fibers forming a meander resistive electrical circuit, the resistor comprising a resistive array electrical resistors short-circuited by conductive strips of metal or alloy foil, characterized in that the incremental ratio AR of the ohmic value when n resistive coupled circuits (Ap ..... p, D, ...) of the series, and ^d todnotou HTN-1 by ^d violations involving n-1 stoudných electrical circuitry in ^series-d satisfying the relationship Δ R ----------. AT RTn-1 n where U _n is the nth member of the absolutely convergent series in the Cauchy criterion and AR = RTn - RTn-1. ' 2. The electrical resistance according to claim 1, characterized in that __ ^й * M * »* ^2-1 · _K 2 _n TRn-1 2.4. ». 2n where K is an adjustable niuneee coefficient less than 1. Surface electrical resistance according to item 1 or 2 with square or rectangular foil, characterized in that the resistive electrical circuitry (A ^, B ^ ..... j · ··· n Djn ···) are grouped in an ilyir separated by a rectangular blocks (21, 22, 32/24) that are disposed along each of the sides (A, B, C, D) of the film (10). Surface electrical resistance according to claim 3, characterized in that the resistive circuits of each block (21, 22, 23, 24) are marked with a numeral number less than or equal to 9 etched into the conductive strip (13-18) located between the associated circuits (Ap · Bp .Cp Dp ...) and the adjacent side (A, B, C, D) of the film (10). 5. The electrical resistance according to claim 1, characterized in that the support on which the film (10) is deposited or glued has a thermal water conductivity equal to or greater than 96% pure alumina. &Quot; 6. The method of adjusting the ohmic value of the electrical resistance of item 1, wherein the cutouts are formed in the conductive strips by means of electrical resistive coupled resistors, characterized in that the cutout is formed in the conductive strip. where the ohmic value increment is as close as possible to the desired value, and then is gradually adjusted by sequentially connecting additional coupled circuits that give the ohmic value increments, which are gradually reduced.