Fabrication and Testing Fabrication and Testing of Thin-Film Igniter of Thin-Film Igniter

Bridge Bridge

Contact: Dr. Azad SiahmakounContact: Dr. Azad SiahmakounDirector, MiNDS FacilityDirector, MiNDS Facility

RoseRose-Hulman-Hulman Institute of TechnologyInstitute of Technology

A Technology Service and Solutions Company

June 30, 2009June 30, 2009

OutlineOutline Problem StatementProblem Statement Circle Thin Film IgnitersCircle Thin Film Igniters

– Resistance Testing and AnalysisResistance Testing and Analysis– Temperature Testing and Distribution Temperature Testing and Distribution – Comparison to Filament IgnitersComparison to Filament Igniters– Optimization and Performance Optimization and Performance

ExperimentationExperimentation Line Thin Film IgnitersLine Thin Film Igniters

– Resistance Testing and AnalysisResistance Testing and Analysis– Temperature Testing and DistributionTemperature Testing and Distribution

Reuse methodsReuse methods ConclusionsConclusions

Problem StatementProblem StatementOptimize reliability of bridge deposited across igniter Optimize reliability of bridge deposited across igniter

terminalsterminals ConstraintsConstraints

– PVD Method: SputteringPVD Method: Sputtering– Material: 80/20 Nickel Chrome (Nichrome)Material: 80/20 Nickel Chrome (Nichrome)– Deposition process must be repeatableDeposition process must be repeatable– Pass No-Fire test (does not reach 350Pass No-Fire test (does not reach 350oo C @ 1 A) C @ 1 A)– Pass All-Fire test (reach 350Pass All-Fire test (reach 350oo C within 20 ms C within 20 ms

when 3.5 A is applied) when 3.5 A is applied)

Circle Thin Film IgnitersCircle Thin Film Igniters Based off Phase 1 results, circle shaped thin film Based off Phase 1 results, circle shaped thin film

igniters were concluded to have the lowest igniters were concluded to have the lowest variation in resistance and highest probability of variation in resistance and highest probability of passing both no-fire and all-fire conditions.passing both no-fire and all-fire conditions.

More than 20 sets of circle igniters were created More than 20 sets of circle igniters were created to optimize thickness and sputtering conditions to optimize thickness and sputtering conditions and were used to test various ideas on improving and were used to test various ideas on improving performance.performance.

Final results showed that the circle igniters Final results showed that the circle igniters required a thickness of 2.4 µm to obtain the 1.0 required a thickness of 2.4 µm to obtain the 1.0 ±± 0.1 ohm requirement and passed the no-fire 0.1 ohm requirement and passed the no-fire condition, however, they could not meet the all-condition, however, they could not meet the all-fire condition.fire condition.

Optimum Circle Igniter Optimum Circle Igniter ResistancesResistances

Set 19 (2.4um) at 25mA (9/22/08)

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

19-1 19-2 19-3 19-4 19-5 19-6 19-7 19-8

Igniter #

Resis

tan

ce (

Oh

m)

Odyssian Igniters 25mA Resistance Test (9/22/08)

0.85

0.9

0.95

1

1.05

1.1

106 111 112 113 114

Igniter Label

Res

ista

nce

(Ohm

)Rose

OdyssianOptimum 1 Ohm circle NiCr igniters deposited at RHIT

Optimum 1 Ohm NiCr circle igniters made at Odyssian

No-Fire Temperature Curves of No-Fire Temperature Curves of Circle IgnitersCircle Igniters

Set 19 (2.4um) (9/23/08)

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6

Time (min)

Tem

p (

C)

19-2: 1.02

19-7: 0.96

Odyssian No Fire (9/23/08)

0

20

40

60

80

100

120

140

160

0 1 2 3 4 5 6

Time (min)

Te

mp

(C

)

113: 0.98

114: 1.04

No-fire test, 1 A for 5 minutes, for both optimum circle igniters from RHIT and Odyssian show a maximum temperature of only 150o C, well below the ignition temperature of 350o C

All-Fire ResultsAll-Fire ResultsOptimum 1 ohm circle igniters fail all-fire condition, taking over 200 ms to heat up to 350o C when 3.5 A is applied

Odyssian Igniters All Fire Tests (9/23/08)

0

50

100

150

200

250

300

350

400

450

500

550

0 50 100 150 200 250 300 350 400 450 500

Time (ms)

Te

mp

(C

) 106: 0.94

111: 0.95

112: 1.08

113: 0.98

EP Filament IgnitersEP Filament Igniters

No Fire Filament Igniter F001 (10/24/08)

0

50

100

150

200

250

300

350

400

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350

Time (ms)

Tem

p (

C)

Temperature trend as current increases, shows filament igniter hitting 350o C at 0.80 A and circle igniter hitting 350o C at 1.45 A

Temperature curve of filament igniter burning out when 1 A is applied, showing failure of no-fire condition. Since proven to pass no-fire tests at EaglePicher, results suggest ignition powder has a big influence on thin film temperature compared to testing in an open environment.

Filament Igniter F001 (10/22/08) compared w ith 1 Ohm circle (19-5)

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200 1400

Current (mA)

Tem

p (

C)

Filament

Circle

Thermal Distribution Thermal Distribution ImagingImaging

Thermal images from IR camera used to create temperature curves

Visual examples of burn patterns on circle thin film igniters

Optimized Sputtering Optimized Sputtering Parameters and Tested Parameters and Tested

Performance ImprovementsPerformance ImprovementsSputtering optimizationSputtering optimization Final thickness depends on location of igniter on mask, middle ring Final thickness depends on location of igniter on mask, middle ring

gives desired thicknessgives desired thickness Lower pressure/more ideal vacuum gives lower resistance and less Lower pressure/more ideal vacuum gives lower resistance and less

defectsdefectsTested possible performance Tested possible performance

improvementsimprovements Annealing: increases resistance, can Annealing: increases resistance, can

cause cracking and peeling of thin filmcause cracking and peeling of thin film Surface smoothing: filling surface pores Surface smoothing: filling surface pores

with PMMA, resulted in adhesion with PMMA, resulted in adhesion problems of thin filmproblems of thin film

Thin film cutting: laser cutting proved to Thin film cutting: laser cutting proved to take too long and too inaccurate for take too long and too inaccurate for detailed designsdetailed designs

SEM image showing adhesion problems from PMMA coating

Line Igniters ResistanceLine Igniters Resistance

RHIT 4.22 um Line Igniters (6/16/09)

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

SP1 SP2 SP3 SP4 SP5 SP6 SP7 Sp8 SP9 SP10 SP11 SP12 SP13 SP14 SP15

Igniter #

Res

ista

nce

(Oh

ms)

Odyssian Line Igniters Initial Resistance (6-9-09)Average 1.143 +/- 0.048 Ohms

0.95

1

1.05

1.1

1.15

1.2

1.25

DB 3 DB 4 DB 5 DB 7 DB 10 TS 39 TS 48 TS 61 TS 63 TS 66

Igniter Label

Re

sis

tan

ce

(O

hm

s)

First attempt of line igniters at RHIT

Dog Bone and Thin Strip line igniters from Odyssian

Ramping Current/No-Fire Test Ramping Current/No-Fire Test on Line Igniterson Line Igniters

RHIT 4.22 um Line Ramp and No Fire Temperature (6/18/09)

0

20

40

60

80

100

120

140

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1000

Current (mA)

Te

mp

era

ture

(C

)

Sp 2 (0.82)

Sp 3 (1.07)

Sp 4 (0.82)

Sp 5 (0.69)

Sp 8 (1.47)

Sp 9 (0.75)

Sp 11 (0.65)

Odyssian Line Ramping Tempature - No Fire (6-11-09)

0

50

100

150

200

250

300

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1000

Current (mA)

Te

mp

(C

)

DB 4 (1.12)

DB 5 (1.14)

DB 7 (1.22)

DB 10 (1.10)

TS 39 (1.19)

TS 39-2 (1.21)

TS 48 (1.20)

TS 61 (1.12)

TS 66 (1.17)

RHIT first line igniter attempt of 4.22 µm, stays under 150o C for no-fire

Odyssian DB and TS line igniters, stays under 250o C for no-fire for all except 1, which is expected for its higher resistance

Line Igniters Temperature Line Igniters Temperature TrendsTrends

Odyssian Line All Fire (6-12-09)

0

50

100

150

200

250

300

350

400

450

500

550

600

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00

Time (ms)

Te

mp

(C

)

DB 5 (1.14)

DB 7 (1.22)

DB 10 (1.10)

TS 39 (1.21)

TS 61 (1.12)

TS 63 (1.09)

TS 66 (1.17)

RHIT 4.22 um Line All Fire Test (6/19/09)

0

50

100

150

200

250

300

350

400

450

500

550

0 50 100 150 200 250 300 350 400 450

Time (ms)

Te

mp

(C

)

Sp 2 (0.82)

Sp 3 (1.07)

Sp 4 (0.82)

Sp 5 (0.69)

Sp 9 (0.75)

Sp 11 (0.65)

Two of RHIT line igniters hit 350o C in 50 ms, the rest took over 250 ms, all well above the 20 ms target

Odyssian line igniters all ignited by 33 ms. Due to the IR camera image rate of every 17 ms and lack of coordination with start time, it is impossible to determine the exact ignition time. Excel curves are not good at defining trend between points, but based on point data and previous curve trends, most of the igniters may have ignited within the 20 ms target

Igniter ReuseIgniter Reuse Three methods were investigated in Three methods were investigated in

removing the thin film: chemical etching, removing the thin film: chemical etching, hand polishing, and drill press polishinghand polishing, and drill press polishing

Chemical etching was best at removing thin Chemical etching was best at removing thin film and NiCr in substrate pores, but eroded film and NiCr in substrate pores, but eroded the casing as well, making it hard to reuse the casing as well, making it hard to reuse in maskin mask

Hand polishing is more effective over drill Hand polishing is more effective over drill press polishing: slower speed prevents grit press polishing: slower speed prevents grit paper damage, easier to focus on specific paper damage, easier to focus on specific tough to reach spots, and can change tough to reach spots, and can change direction of scratching to prevent deep direction of scratching to prevent deep grooves forminggrooves forming

Chemical etching example

Compared polishing images, left is hand polishing, right is drill press polishing

ConclusionsConclusions

Line igniters show promise of meeting both no-Line igniters show promise of meeting both no-fire and all-fire conditionsfire and all-fire conditions

More accurate recording of igniter burnout time More accurate recording of igniter burnout time can be done with a digital oscilloscopecan be done with a digital oscilloscope

Need more tests to determine which line style, Need more tests to determine which line style, DB or TS, that produces more consistent DB or TS, that produces more consistent resistance and more successful test results resistance and more successful test results

Igniter BackgroundIgniter Background

Figure 1: Thermal Battery Cross-Section Figure 2: Igniter Cross-Section

Bridge Wire

Experimental Setup and Experimental Setup and DesignDesign