Philips Components Chip resistors General Introduction Exceptions to this rule are customer/application specific resistors that are not included in our standard series, such as higher ohmic values and non-standard values. INTRODUCTION Data in data sheets is presented - whenever possible according to a `format', in which the following chapters are stated: * TITLE FUNCTIONAL DESCRIPTION * FEATURES The functional description includes: nominal resistance range and tolerance, limiting voltage, temperature coefficient, absolute maximum dissipation, climatic category and stability. * APPLICATIONS * DESCRIPTION * QUICK REFERENCE DATA The limiting voltage (DC or RMS) is the maximum voltage that may be continuously applied to the resistor element, see "IEC publications 115-8". * ORDERING INFORMATION * FUNCTIONAL DESCRIPTION - Product characterization The temperature rise in a resistor due to power dissipation, is determined by the laws of heat - conduction, convection and radiation. The maximum body temperature usually occurs in the middle of the resistor and is called the hot-spot temperature. - Limiting values * MECHANICAL DATA - Mass - Marking In the normal operating temperature range of chip resistors the temperature rise at the hot-spot, T, is proportional to the power dissipated: T = A x P. The proportionally constant `A' gives the temperature rise per Watt of dissipated power and can be interpreted as a thermal resistance in K/W. This thermal resistance is dependent on the heat conductivity of the materials used (including the PCB), the way of mounting and the dimensions of the resistor. The sum of the temperature rise and the ambient temperature is: - Outlines * TESTS AND REQUIREMENTS The chapters listed above are explained in this section "General Introduction Chip resi stors", with detailed information in the relevant data sheet. Chapters "Mounting" and "Packaging" are detailed in separate sections. DESCRIPTION Tm = Tamb + T All types of chip resistors have a rectangular ceramic body. The resistive element is a metal glaze film. The chips have been trimmed to the required ohmic resistance by cutting one or more grooves in the resistive layer. This process is completely computer controlled and yields a high reliability. The terminations are attached using either a silver dipping method or by applying nickel terminations which are covered with lead/tin. where: Tm = hot-spot temperature Tamb = ambient temperature T = temperature rise at hot-spot. The stability of a chip resistor during endurance tests is mainly determined by the hot-spot temperature and the resistive materials used. The resistive layer is coated with a coloured protective layer. This protective layer provides electrical, mechanical and/or environmental protection - also against soldering flux and cleaning solvents, in accordance with "MIL-STD-202E", method 215 and "IEC 68-2-45". Summarizing DESCRIPTION RELATIONSHIP Dimensions, conductance of materials and mounting determine heat resistance ORDERING INFORMATION Heat resistance x dissipation gives temperature rise Resistors are ordered by their ordering code, a 12-digit number. In general, the packaging method and resistance code are integral parts of this number. Temperature rise + ambient temperature give hot-spot temperature 1996 Nov 15 1 Philips Components Chip resistors General Introduction Performance EXAMPLE When specifying the performance of a resistor, the dissipation is given as a function of the hot-spot temperature, with the ambient temperature as a parameter. If the temperature coefficient of a resistor of Rnom = 1 k between -55 C and +155 C is 200 x 10-6/K, its resistance will be, at 25 C: From T = A x P and Tm = Tamb + T it follows that: 1000 (nominal = rated value) T m - T amb P = -------------------------A at +155 C: 1000 (130 x 200 x 10-6) x 1000 = 1026 or 974 If P is plotted against Tm for a constant value of A, parallel straight lines are obtained for different values of the ambient temperature. The slope of these lines, at -55 C: 1000 (80 x 200 x 10-6) x 1000 = 1016 or 984 I dP ----------- = ---A dT m If the temperature coefficient is specified as 200 x 10-6/K the resistance will be within the shaded area as shown in Fig.1. is the reciprocal of the heat resistance and is the characteristic for the resistor and its environment. The temperature coefficient The temperature coefficient of resistance is a ratio which indicates the rate of increase (decrease) of resistance per Kelvin (K) increase (decrease) of temperature within a specified range, and is expressed in parts per million per K (x10-6/K). handbook, full pagewidth 26 2.6% 1.6% R nom 1.6% 55 0 o 25 T ( C) 155 16 2.6% MGA208 Fig.1 Temperature coefficient. 1996 Nov 15 2 Philips Components Chip resistors General Introduction Basically, chip resistors can be represented by an ideal resistor switched in series with a coil and both switched parallel to a capacitor. The values of the capacitance and inductance are mainly determined by the dimensions of the terminations and the conductive path length. The trimming pattern has a negligible influence on the inductance as the path length is not influenced. Also, its influence on the capacitance is negligible as the total capacitance is largely determined by the terminations. Noise Most resistors generate noise due to the passage of current through the resistor. This noise is dependent on the amount of current, the resistive material and the physical construction of the resistor. The physical construction is partly influenced by the laser trimming process which cuts a groove in the resistive material. Typical current noise levels are shown in Fig.2. MGA212 12 handbook, noise halfpage level V V The environment surrounding chips (e.g. landing paths, nearby tracks and the material of the printed-circuit board) has a large influence on the behaviour of the chip on the printed-circuit board. spec. level Typical values of capacitance and inductance 8 CHIP PROPERTIES 4 QUANTITY 0 THIN FILM 1206 R < 1 k 1 10 100 1k 10 k 100 k 1M 10 M R () THICK FILM 1206 0805 0603 Capacitance 0.05 pF 0.05 pF 0.09 pF 0.05 pF Inductance 2 nH 2 nH 1 nH 0.4 nH RC02 Fig.2 Typical noise levels as a function of rated resistance. Frequency behaviour Resistors in general are designed to function according to ohmic laws. This is basically true of rectangular chip resistors for frequencies up to 100 kHz. At higher frequencies, the capacitance of the terminations and the inductance of the resistive path length begin to have an effect. 1996 Nov 15 MLB715 Fig.3 Equivalent circuit. 3 Philips Components Chip resistors General Introduction MLB716 2.0 handbook, full pagewidth Z R 1.6 Rn = 1 Rn = 10 1.2 Rn = 100 0.8 Rn = 1 M Rn = 10 k Rn = 100 k Rn = 1 k 0.4 0 10 6 10 7 10 8 10 9 1010 f (Hz) Size 0603 Fig.4 Impedance as a function of frequency for a chip resistor. MLB717 100 handbook, full pagewidth (deg) 60 Rn = 1 Rn = 10 20 Rn = 100 20 Rn = 1 M Rn = 10 k Rn = 100 k Rn = 1 k 60 100 10 6 10 7 10 8 10 9 Size 0603 Fig.5 Phase shift as a function of frequency for a chip resistor. 1996 Nov 15 4 f (Hz) 1010 Philips Components Chip resistors General Introduction MLB718 2.0 handbook, full pagewidth Z R 1.6 Rn = 1 Rn = 100 Rn = 10 1.2 0.8 Rn = 1 M Rn = 10 k Rn = 100 k Rn = 1 k 0.4 0 10 6 10 7 10 8 10 9 1010 f (Hz) Size 0805 Fig.6 Impedance as a function of frequency for a chip resistor. MLB719 100 handbook, full pagewidth (deg) 60 Rn = 1 Rn = 10 20 Rn = 100 20 Rn = 1 M Rn = 10 k Rn = 100 k Rn = 1 k 60 100 10 6 10 7 10 8 10 9 Size 0805 Fig.7 Phase shift as a function of frequency for a chip resistor. 1996 Nov 15 5 f (Hz) 1010 Philips Components Chip resistors General Introduction MLB720 2.0 handbook, full pagewidth Z R 1.6 Rn = 1 Rn = 100 Rn = 10 1.2 0.8 Rn = 1 M Rn = 100 k Rn = 10 k Rn = 1 k 0.4 0 10 6 10 7 10 8 10 9 1010 f (Hz) Size 1206 Fig.8 Impedance as a function of frequency for a chip resistor. MLB721 100 handbook, full pagewidth (deg) 60 Rn = 1 Rn = 10 20 Rn = 100 20 Rn = 1 M Rn = 10 k Rn = 100 k Rn = 1 k 60 100 10 6 10 7 10 8 10 9 Size 1206 Fig.9 Phase shift as a function of frequency for a chip resistor. 1996 Nov 15 6 f (Hz) 1010 Philips Components Chip resistors General Introduction With this test, it can be determined at which applied voltage the resistive value changes about 0.5% of its nominal value under the above mentioned pulse conditions. Figure 10 shows test results for the RC02 chip resistors. If applied regularly the load is destructive, therefore the load must not be applied regularly during the load life of the resistors. However, the magnitude of a pulse at which failure occurs is of little practical value. The maximum `single-pulse' load that may be applied in a regular way can be determined in a similar manner. PULSE-LOAD BEHAVIOUR The load, due to a single pulse at which chip resistors fail by going open circuit, is determined by shape and time. A standard way to establish pulse load limits is shown in Table 1. Table 1 Pulse load limits PARAMETER VALUE UNIT Exponential time constant 50 to 700 s Repetition time 12 to 25 s Amount of pulses 5 to 10 MBD641 10 4 handbook, full pagewidth Vmax (V) 1.2/50 s 10 3 10/700 s 10 2 10 10 10 2 10 3 10 4 10 5 10 6 R n () RC02 Fig.10 Maximum permissible peak pulse voltage ( V max ) without failing to `open circuit' in accordance with DIN IEC 40 (CO) 533. 1996 Nov 15 7 10 7 Philips Components Chip resistors General Introduction MBC188 3 10 handbook, full pagewidth Pmax (W) 10 2 single pulse 10 t p / t i = 1000 1 repetitive pulse 10 1 10 6 10 5 10 4 10 3 10 2 10 1 t i (s) 1 RC02G Fig.11 Pulse on a regular basis; maximum permissible peak pulse power ( P max ) as a function of pulse duration for R 10 k, single pulse and repetitive pulse tp/ti = 1000. MBD586 600 handbook, full pagewidth Vmax (V) 400 200 0 10 6 10 5 10 4 10 3 10 2 10 1 t i (s) RC02 Fig.12 Pulse on a regular basis; maximum permissible peak pulse voltage ( V max ) as a function of pulse duration (ti). 1996 Nov 15 8 1 Philips Components Chip resistors General Introduction Definitions of pulses Determination of pulse-load SINGLE PULSE The graphs in Figs 11 and 12 may be used to determine the maximum pulse-load for a resistor. The resistor is considered to be operating under single pulse conditions if, during its life, it is loaded with a limited number (approximately 1500) of pulses over long time intervals (greater than one hour). * For repetitive rectangular pulses: 2 V i - ------- must be lower than the value of Pmax given by R the solid lines of Fig.11 for the applicable value of ti and duty cycle tp/ti. REPETITIVE PULSE The resistor is operating under repetitive pulse conditions if it is loaded by a continuous train of pulses of similar power. - Vi must be lower than the value of Vmax given in Fig.12 for the applicable value of ti. The dashed line in Fig.11 shows the observed maximum load for the RC02G chip resistors under single-pulse loading. * For repetitive exponential pulses: - As for rectangular pulses, except that ti = 0.5 . * For single rectangular pulses: More usually, the resistor must withstand a continuous train of pulses of repetition time `tp' during which only a small resistance change is acceptable. This resistance change (R/R) is equal to the change permissible under continuous load conditions. The continuous pulse train and small permissible resistance change reduces the maximum handling capability. 2 V i - ------- must be lower than the Pmax given by the dashed R line of Fig.11 for the applicable value of ti. - Vi must be lower than the value of Vmax given in Fig.12 for the applicable value of ti. The continuous pulse train maximum handling capacity of chip resistors has been determined experimentally. Measurements have shown that the handling capacity varies with the resistive value applied. However, maximum peak pulse voltages as indicated in Fig.12, should not be exceeded. 1996 Nov 15 9 Philips Components Chip resistors General Introduction Definition of symbols (see Figs 11, 12, 13 and 14) SYMBOL DESCRIPTION P applied peak pulse power P max maximum permissible peak pulse power (Fig.11) Vi applied peak pulse voltage (Figs 13 and 14) V max maximum permissible peak pulse voltage (Fig.12) Rnom nominal resistance value ti pulse duration (rectangular pulses) tp pulse repetition time time constant (exponential pulses) Tamb ambient temperature Tm(max) maximum hot-spot temperature of the resistor MGA206 handbook, halfpage V tp ti Vi t Examples Determine the stability of a typical resistor for operation under the following pulse-load conditions. Fig.13 Rectangular pulses. CONTINUOUS PULSE TRAIN A 100 resistor is required to operate under the following conditions: Vi = 10 V; ti = 10-5 s; tp = 10-2 s. Therefore: 2 -2 t 10 10 = 1000 P = ---------- = 1 W and ---p- = -----------5 100 ti 10 t For ti = 10-5 s and ---p- = 1000, Fig.11 gives Pmax = 2 W ti and Fig.12 gives Vmax = 400 V. As the operating MGA207 handbook, halfpage V tp conditions P = 1 W and Vi = 10 V are lower than these limiting values, this resistor may be safely used. SINGLE PULSE A 10 k resistor is required to operate under the following conditions: Vi = 250 V; ti = 10-5 s. t Therefore: 2 250 Pmax = ---------------- = 6.25 W 10000 The dashed curve of Fig.11 shows that at ti = 10-5 s, the permissible Pmax = 10 W and Fig.12 shows a permissible Fig.14 Exponential pulses. Vmax of 400 V, so this resistor may be used. 1996 Nov 15 10 Philips Components Chip resistors General Introduction MECHANICAL DATA Outlines handbook, full pagewidth T ,, , ,, ,, ,, , ,, ,, protective coat resistor layer inner electrode end termination ceramic substrate protective coat W MBC695 L For dimensions see Table 2. Fig.15 Component outline. Table 2 Chip resistor type; USA case size code; mass per 100 units and relevant physical dimensions; see Fig.15 USA SIZE CODE L (mm) W (mm) T (mm) MASS (g) RC0... 1206 3.2 1.6 0.6 1.0 RC1.. 0805 2.0 1.25 0.6 0.55 RC2.. 0603 1.6 0.8 0.45 0.25 RC3. 0402 1.0 0.5 0.35 0.052 TYPE Marking Table 3 Resistance value indication Wherever possible chip resistors are provided with a resistance code; see Table 3. The resistance code includes the first two or three significant digits of the resistance value (in ohms) followed by the number of zeros to follow. Whether two or three significant values are represented depends on the tolerance: INDICATOR TOL. 2% TOL. 1% 0 0.0 ; jumper - 1 to 91 1 to 976 R(1) 1 100 to 910 1 to 9.76 k 2 1 to 9.1 k 10 to 97.6 k * 5% requires two digits 3 10 to 91 k 100 to 976 k * 2% tolerance may be marked with two or three digits 4 100 to 910 k 1 M * 1% and lower requires three digits. 5 1 to 9.1 M 6 10 M Note 1. R denotes the decimal point. 1996 Nov 15 11 - - Philips Components Chip resistors General Introduction in the specified climatic category and in accordance with IEC publication 68, "Recommended basic climatic and mechanical robustness testing procedure for electronic components". In some instances deviations from the IEC recommendations are made. TESTS AND PROCEDURES To guarantee zero defect production standards, Statistical Process Control is an essential part of our production processes. Furthermore, our production process is operating in accordance with "ISO 9000". Tests and their requirements are described in detail in the datasheets. Essentially all tests on resistors are carried out in accordance with the schedule of "IEC publication 115-1" MGA210 300 TC halfpage handbook, 6 (10 spec. level /K) 200 (10 20 0 0 100 spec. level /K) 40 100 20 spec. level 200 300 MGA211 60 TC halfpage handbook, 6 1 10 100 1k 10 k 100 k 40 60 100 1M 10 M R () spec. level 1k 10 k 100 k 1M R () b. RC02G. a. RC01. Fig.16 Typical temperature coefficients between the lower and upper category temperatures. 1996 Nov 15 12 Philips Components Chip resistors General Introduction MGA214 1.2 R (%) handbook, R halfpage spec. level 0.8 R (%) 0.1 0 0 0.4 0.1 1.2 0.2 spec. level 1 10 100 1k spec. level 0.2 0.4 0.8 MGA215 0.3 handbook, R halfpage 10 k 100 k spec. level 0.3 100 1M 10 M R () 1k 10 k 100 k 1M R () a. RC01. b. RC02G. Fig.17 Typical percentage change in resistance after soldering for 10 seconds at 260 C, completely immersed. MGA213 12 handbook, halfpage noise level V V 8 spec. level 4 0 100 1k 10 k 100 k 1M R () RC02G Fig.18 Typical noise level as a function of rated resistance measured using Quantech - equipment. 1996 Nov 15 13 Philips Components Chip resistors General Introduction MGA216 handbook, Rhalfpage R (%) MGA217 1.2 handbook, R halfpage 2 R (%) spec. level 1 spec. level 0.8 0.4 0 0 1 0.4 spec. level 0.8 spec. level 2 1 10 100 1k 10 k 100 k 1.2 100 1M 10 M R () 1k 10 k 100 k 1M R () a. RC01. b. RC02G. Fig.19 Typical percentage change in resistance after 56 days at 40 C and 90 to 95% relative humidity loaded with Pnom. MGA218 1.2 handbook, R halfpage R (%) spec. level 0.8 R (%) 0.2 0 0 0.4 0.2 1.2 0.4 spec. level 1 10 100 1k 10 k 100 k spec. level 0.4 0.4 0.8 MGA219 0.6 handbook, R halfpage 0.6 100 1M 10 M R () spec. level 1k 10 k 1M R () a. RC01. b. RC02G. Fig.20 Typical percentage change in resistance after 1000 hours loaded with Pnom at 70 C ambient temperature. 1996 Nov 15 100 k 14