Ferro Electronic Material Systems Performance of LTCC Resistors in Extreme Cold Environment Michail Moroz IMAPS ATW on Reliability of Advanced Electronic Packages and Devices in Extreme Cold Environments February 21-23, 2005 Pasadena, CA
Introduction (1) There is a growing demand for more capable extreme cold • environment electronics used in such applications as defense and aerospace systems Many space applications like exploration missions to the outer • planets, James Webb Space Telescope, earth-orbiting and deep-space probes and communications satellites, would benefit from availability of low temperature electronics Continuous interest in miniaturized, high performance and reliable • electronic devices drives the electronic industry to develop new packaging technologies In competition with alternative solutions like printed circuit board • and thin film technologies, low temperature co-fired ceramic (LTCC) technology is being developed for the fabrication of high reliability, compact, low-cost electronic modules 2
Introduction (2) Most modern electronic components are limited to low operating • temperature of -40ºC to -55ºC Effect of extreme cold temperatures on the key characteristics of • resistors, specifically resistance and temperature coefficient of resistance (TCR) was investigated The following requirements were set as a goal for the present work: • � Resistivity: from 10 Ω / � to 100 K Ω / � � Resistor size range: 15x15 to 80x80 mils and 40x40 to 400x40 mils � Temperature range: from 25 ° C down to –155 ° C � TCR: within ± 100 ppm/ ° C � Relative resistivity change: < ± 1% � R 1 / R 2 ratio change for resistor pairs: < ± 0.5% 3
TCR Temperature Coefficient of Resistance (TCR) – the amount of resistance • change of a resistor material with temperature TCR is also dependent on resistor geometry, resistor thickness, trimming • methods, encapsulation, and many other processing parameters Values are often quoted for "hot TCR" and "cold TCR" • Commonly expressed as the average change over a certain temperature • range in parts per million per degree Centigrade (ppm/ ° C) − ( R R ) 2 1 x 10 6 , ppm/ ° C TCR: − R ( T T ) 1 2 1 The standard TCR test uses only two readings at - 55 ° C and + 125 ° C • with reference point 25 ° C No thick film resistive inks with specified and controlled continuous • TCR curve shape for wide resistor size range are currently commercially available 4
Resistor Test Pattern Resistor sizes, mils: 15x15 40x40 20x20 80x40 30x30 120x40 40x40 200x40 80x80 400x40 Pattern size: 1” x 1” 5
The TCR Test System The TCR Test System enables computer-controlled • measurement of resistance and calculation of the TCR The TCR Chamber door is equipped with five • connectors that can accommodate up to 20 resistor samples The TCR Chamber is cooled by liquid nitrogen • The operator enters a series of test temperatures and dwell • time at each temperature into the system After the programmed dwell time at each temperature, the • resistance is measured for each sample The TCR is calculated for each sample using the test results at • a user defined reference temperature Test results for each test session are stored in a Microsoft • Access database and accessed using a unique test file name 6
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Relative Resistivity 11
TCR vs. Resistor Size in Regular Temperature Range from –55 ° C to 125 ° C 200 100 Regular Hybrid Resistor High Precision LTCC 82-31PMG Resistor 80 150 Reference Point: +25C Reference Point: +25C 60 100 40 50 TCR, ppm/°C 20 TCR, ppm 0 0 -20 -50 -40 Hot @ 125°C -100 Hot @ 125°C -60 Cold @ -55°C -150 Cold @ -55°C -80 -200 -100 40x40 80x40 120x40 200x40 400x40 40x40 80x40 120x40 200x40 400x40 Temperature, °C Temperature, °C 12
TCR vs. Temperature in Standard Temperature Range from –55 ° C to 125 ° C 100 Such feature of thick High Precision LTCC 82-31PMG Resistor 80 film resistive inks like specified and 60 Reference Point: +25°C controlled continuous 40 TCR curve shape for wide resistor size 20 TCR, ppm range is very 0 desirable, as it provides significant -20 design flexibility and -40 helps to keep resistor performance precise -60 40x40 80x40 120x40 200x40 400x40 for various circuit -80 designs, facilitating -100 enhanced yield -55 -45 -35 -25 -15 -5 0 5 45 55 65 75 85 95 105 115 125 during manufacturing Temperature, °C 13
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New High Precision LTCC Resistor Regular Resistor < ±100 ppm°C @ -55°C 15
New High Precision LTCC Resistor Regular Resistor < ±100 ppm°C @ -55°C 16
TCR in the Temperature Range from 25 ° C to -155 ° C for 20x20 mils Resistors 100 Reference Point: +25°C 50 0 -50 TCR, ppm/°C -100 -150 20 x 20 mils Resistors -200 High Precision 82-51PMG Resistor -250 Regular ± 100 ppm/°C Resistor -300 -350 5 5 5 0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 - 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 2 1 - - - - - - - - - 1 1 1 1 1 1 - - - - - - Temperature, °C 17
Relative Resistivity Change in the Temperature Range from 25 ° C to -155 ° C (20x20 mils size) 1.00 0.50 0.00 Relative Resistivity Change, % -0.50 -1.00 -1.50 -2.00 -2.50 Reference Point: +25°C -3.00 -3.50 20 x 20 mils Resistors -4.00 -4.50 High Precision 82-51PMG Resistor -5.00 Regular ± 100 ppm/°C Resistor -5.50 -6.00 5 5 5 0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 2 1 - 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - - - - - - - - - 1 1 1 1 1 1 - - - - - - Temperature, °C 18
TCR in the Temperature Range from 25 ° C to -155 ° C 100 100 Regular Hybrid Resistor High Precision LTCC 82-31PMG Resistor 50 80 60 0 40 -50 TCR, ppm/°C TCR, ppm/°C 20 -100 0 -150 40X40 -20 -200 80X40 -40 Reference Point: +25°C 120X40 -250 200X40 -60 Reference Point: +25°C -300 400X40 40X40 80X40 120X40 200X40 400X40 -80 -350 -100 5 5 5 0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 2 1 - 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - - - - - - - - - 1 1 1 1 1 1 25 15 5 0 -5 -15 -25 -35 -45 -55 -65 -75 -85 -95 -105 -115 -125 -135 -145 -155 - - - - - - Temperature, °C Temperature, °C For extreme temperature applications continuous TCR curve with a controlled slope is a newly introduced, but mandatory requirement 19
Relative Resistivity Change in the Temperature Range from 25 ° C to -155 ° C 1.00 1.00 Regular Hybrid Resistor High Precision LTCC 82-31PMG Resistor 0.50 0.80 0.00 Relative Resistivity Change, % 0.60 -0.50 Relative Resistivity Change, % -1.00 0.40 -1.50 0.20 -2.00 -2.50 0.00 40X40 -3.00 80X40 -0.20 -3.50 Reference Point: +25°C 120X40 -4.00 -0.40 200X40 -4.50 -0.60 400X40 -5.00 Reference Point: +25°C 40X40 80X40 120X40 200X40 400X40 -5.50 -0.80 -6.00 -1.00 0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 2 1 - 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - - - - - - - - - 1 1 1 1 1 1 - - - - - - 25 15 5 0 -5 -15 -25 -35 -45 -55 -65 -75 -85 -95 -105 -115 -125 -135 -145 -155 Temperature, °C Temperature, °C 20
R 1 /R 2 Ratio of Resistor Pair Quite often pairs of resistors are used in circuit design when • R 1 / R 2 ratio is even more important than their absolute values If two resistors with a different number of squares are used, and • one resistor is changing TCR faster than the other (i.e. has a different TCR curve slope), this would be an indication the R 1 / R 2 ratio is not at –155 ° C as accurately as with the standard temperature range of –55 ° C For the pair consisting of same-width 10-square and 1-square • precise regular resistors with TCR ± 100 ppm/ ° C at –55 ° C, the R 1 / R 2 ratio change at –155 ° C was as high as -2.5% The R 1 / R 2 ratio change for the specifically designed 82-series • LTCC post fired resistors did not exceed ± 0.2% at -155 ° C for any resistor configuration 21
R 1 /R 2 Ratio Change in the Temperature Range from 25 ° C to -155 ° C 1.00 1.00 High Precision LTCC 82-31PMG Resistor Regular Hybrid Resistor 0.80 0.50 Reference Point: +25°C 0.60 Reference Point: +25°C 0.00 0.40 R1 / R2 Change, % R1 / R2 Change, % -0.50 0.20 0.00 -1.00 400x40 / 40x40 -0.20 -1.50 400x40 / 40x40 400x40 / 80x40 -0.40 -2.00 400x40 / 80x40 400x40 / 120x40 -0.60 400x40 / 120x40 -2.50 -0.80 400x40 / 200x40 400x40 / 200x40 -3.00 -1.00 25 15 5 0 -5 -15 -25 -35 -45 -55 -65 -75 -85 -95 -105 -115 -125 -135 -145 -155 25 15 5 0 -5 -15 -25 -35 -45 -55 -65 -75 -85 -95 -105 -115 -125 -135 -145 -155 Temperature, °C Temperature, °C 22
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