Ferro Electronic Material Systems Performance of LTCC Resistors in - - PowerPoint PPT Presentation

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

• f 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

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• 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 KΩ/ 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% R1 / R2 ratio change for resistor pairs: < ± 0.5%

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Introduction (2)

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• 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)

TCR

TCR:

) ( ) (

1 2 1 1 2

T T R R R − −

x 106, ppm/°C

• 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

Resistor Test Pattern

Resistor sizes, mils: 15x15 40x40 20x20 80x40 30x30 120x40 40x40 200x40 80x80 400x40 Pattern size: 1” x 1”

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• 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

The TCR Test System

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8

9

10

Relative Resistivity

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TCR vs. Resistor Size in Regular Temperature Range from –55°C to 125°C

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• 200
• 150
• 100
• 50

50 100 150 200 40x40 80x40 120x40 200x40 400x40 Temperature, °C TCR, ppm/°C Hot @ 125°C Cold @ -55°C

Reference Point: +25C

Regular Hybrid Resistor

• 100
• 80
• 60
• 40
• 20

20 40 60 80 100 40x40 80x40 120x40 200x40 400x40 Temperature, °C TCR, ppm Hot @ 125°C Cold @ -55°C

Reference Point: +25C

High Precision LTCC 82-31PMG Resistor

TCR vs. Temperature in Standard Temperature Range from –55°C to 125°C

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• 100
• 80
• 60
• 40
• 20

20 40 60 80 100

• 55
• 45
• 35
• 25
• 15
• 5

5 45 55 65 75 85 95 105 115 125

Temperature, °C TCR, ppm

40x40 80x40 120x40 200x40 400x40 High Precision LTCC 82-31PMG Resistor

Reference Point: +25°C

Such feature of thick film resistive inks like specified and controlled continuous TCR curve shape for wide resistor size range is very desirable, as it provides significant design flexibility and helps to keep resistor performance precise for various circuit designs, facilitating enhanced yield during manufacturing

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New High Precision LTCC Resistor Regular Resistor < ±100 ppm°C @ -55°C

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New High Precision LTCC Resistor Regular Resistor < ±100 ppm°C @ -55°C

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TCR in the Temperature Range from 25°C to -155°C for 20x20 mils Resistors

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• 350
• 300
• 250
• 200
• 150
• 100
• 50

50 100

2 5 1 5 5

• 5
• 1

5

• 2

5

• 3

5

• 4

5

• 5

5

• 6

5

• 7

5

• 8

5

• 9

5

• 1

5

• 1

1 5

• 1

2 5

• 1

3 5

• 1

4 5

• 1

5 5

Temperature, °C TCR, ppm/°C

High Precision 82-51PMG Resistor Regular ± 100 ppm/°C Resistor

Reference Point: +25°C

20 x 20 mils Resistors

Relative Resistivity Change in the Temperature Range from 25°C to -155°C (20x20 mils size)

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• 6.00
• 5.50
• 5.00
• 4.50
• 4.00
• 3.50
• 3.00
• 2.50
• 2.00
• 1.50
• 1.00
• 0.50

0.00 0.50 1.00

2 5 1 5 5

• 5
• 1

5

• 2

5

• 3

5

• 4

5

• 5

5

• 6

5

• 7

5

• 8

5

• 9

5

• 1

5

• 1

1 5

• 1

2 5

• 1

3 5

• 1

4 5

• 1

5 5

Temperature, °C Relative Resistivity Change, %

High Precision 82-51PMG Resistor Regular ± 100 ppm/°C Resistor

Reference Point: +25°C

20 x 20 mils Resistors

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• 350
• 300
• 250
• 200
• 150
• 100
• 50

50 100

2 5 1 5 5

• 5
• 1

5

• 2

5

• 3

5

• 4

5

• 5

5

• 6

5

• 7

5

• 8

5

• 9

5

• 1

5

• 1

1 5

• 1

2 5

• 1

3 5

• 1

4 5

• 1

5 5

Temperature, °C TCR, ppm/°C

40X40 80X40 120X40 200X40 400X40

Reference Point: +25°C

Regular Hybrid Resistor

• 100
• 80
• 60
• 40
• 20

20 40 60 80 100

25 15 5

• 5
• 15
• 25
• 35
• 45
• 55
• 65
• 75
• 85
• 95
• 105 -115 -125 -135 -145 -155

Temperature, °C TCR, ppm/°C

40X40 80X40 120X40 200X40 400X40

Reference Point: +25°C

High Precision LTCC 82-31PMG Resistor

TCR in the Temperature Range from 25°C to -155°C

For extreme temperature applications continuous TCR curve with a controlled slope is a newly introduced, but mandatory requirement

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• 6.00
• 5.50
• 5.00
• 4.50
• 4.00
• 3.50
• 3.00
• 2.50
• 2.00
• 1.50
• 1.00
• 0.50

0.00 0.50 1.00

2 5 1 5 5

• 5
• 1

5

• 2

5

• 3

5

• 4

5

• 5

5

• 6

5

• 7

5

• 8

5

• 9

5

• 1

5

• 1

1 5

• 1

2 5

• 1

3 5

• 1

4 5

• 1

5 5

Temperature, °C Relative Resistivity Change, %

40X40 80X40 120X40 200X40 400X40

Reference Point: +25°C

Regular Hybrid Resistor

• 1.00
• 0.80
• 0.60
• 0.40
• 0.20

0.00 0.20 0.40 0.60 0.80 1.00

25 15 5

• 5
• 15
• 25
• 35
• 45
• 55
• 65
• 75
• 85
• 95
• 105
• 115
• 125
• 135
• 145
• 155

Temperature, °C Relative Resistivity Change, %

40X40 80X40 120X40 200X40 400X40

Reference Point: +25°C

High Precision LTCC 82-31PMG Resistor

Relative Resistivity Change in the Temperature Range from 25°C to -155°C

• Quite often pairs of resistors are used in circuit design when

R1 / R2 ratio is even more important than their absolute values

• If two resistors with a different number of squares are used, and
• ne resistor is changing TCR faster than the other (i.e. has a

different TCR curve slope), this would be an indication the R1 / R2 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 R1 / R2 ratio change at –155°C was as high as -2.5%

• The R1 / R2 ratio change for the specifically designed 82-series

LTCC post fired resistors did not exceed ± 0.2% at -155°C for any resistor configuration

R1/R2 Ratio of Resistor Pair

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22

• 1.00
• 0.80
• 0.60
• 0.40
• 0.20

0.00 0.20 0.40 0.60 0.80 1.00

25 15 5

• 5
• 15
• 25
• 35
• 45
• 55
• 65
• 75
• 85
• 95
• 105
• 115
• 125
• 135
• 145
• 155

Temperature, °C R1 / R2 Change, %

400x40 / 40x40 400x40 / 80x40 400x40 / 120x40 400x40 / 200x40

Reference Point: +25°C

High Precision LTCC 82-31PMG Resistor

• 3.00
• 2.50
• 2.00
• 1.50
• 1.00
• 0.50

0.00 0.50 1.00

25 15 5

• 5
• 15
• 25
• 35
• 45
• 55
• 65
• 75
• 85
• 95
• 105
• 115
• 125
• 135
• 145
• 155

Temperature, °C

R1 / R2 Change, % 400x40 / 40x40 400x40 / 80x40 400x40 / 120x40 400x40 / 200x40 Reference Point: +25°C

Regular Hybrid Resistor

R1/R2 Ratio Change in the Temperature Range from 25°C to -155°C

• LTCC co-fired buried resistors must be stable and able to undergo

several refirings with minimal performance change

• Termination ink composition effects resistivity and TCR shift after

re-firing

• Co-fired buried resistors are completely surrounded by the sintering

tape and tend to interact with the tape during firing and refirings resulting in unpredictable shifts in resistivity and TCR.

• TCR of the new Ferro experimental co-fired buried resistors after a

first firing and third re-firing did not exceed ± 100 ppm/°C for any resistor size from 15x15 mils to 80x80 mils in the temperature range from –150°C to 300°C

Co-fired Buried LTCC Resistors

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• 100
• 75
• 50
• 25

25 50 75 100

• 1

5

• 1

3

• 1

1

• 9
• 7
• 5
• 3
• 1

1 7 5 1 1 2 5 1 5 1 7 5 2 2 2 5 2 5 2 7 5 3

Temperature, °C TCR, ppm/°C

15x15 20x20 30x30 40x40 80x80

Reference Point: +25°C

30 Ohm/Sq

CN33-398 100% Ag Conductor

Co-fired Buried After First Firing

A6S Tape

• 100
• 75
• 50
• 25

25 50 75 100

• 1

5

• 1

3

• 1

1

• 9
• 7
• 5
• 3
• 1

1 7 5 1 1 2 5 1 5 1 7 5 2 2 2 5 2 5 2 7 5 3

Temperature, °C TCR, ppm/°C

15x15 20x20 30x30 40x40 80x80

Reference Point: +25C

CN33-398 100% Ag Conductor 30 Ohm/Sq

Co-fired Buried After Third Re-Firing

A6S Tape

TCR of Co-fired Buried LTCC Resistors in the Temperature Range from -155 °C to +300°C

Summary

Ferro new LTCC resistor inks have the following:

• Performance:

Resistivity from 10 Ω/ to 100 KΩ/ TCR within ± 100 ppm/°C Relative resistivity change: < ±1% R1 / R2 ratio change for resistor pairs: < ± 0.5%

• Distinctive features:

Resistor size ranges: 15x15 to 80x80 mils and 40x40 to 400x40

mils

Minimized and specified sensitivity to firing / re-firing conditions Controllable and minimized TCR curve slope that: Assures precise resistor performance at extreme temperature

range

Is a mandatory newly introduced resistor characteristic of

thick film resistive materials designated for working at extreme temperature environments

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Future Plans

• Find an opportunity to test described resistive

material system at absolute zero temperature

• Conduct testing for defining of maximum
• perating temperature (~400°C or higher)
• Test LTCC resistors microwave performance

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