High Temperature Ferric Chloride Etching
An Evaluation of the Process
Randy MarkleChemcut
MaterialsCarbon Steel 1020 – 0.2%C, 0.45%Mn, 0.25%Si
301 Stainless Steel – 17%Cr, 7%Ni, 0.15%C
304 Stainless Steel – 18.5%Cr, 9.5%Ni, 0.08%C
316 Stainless Steel – 17%Cr, 12%Ni, 2.25%Mo, 0.08%C
410 Stainless Steel – 12%Cr, 0.15%C
430 Stainless Steel – 17%Cr, 0.12%C
Kovar – 29%Ni, 17%Co
Brass – Alloy 260 (Cartridge Brass) – 70%Cu, 30%Zn
Copper – Alloy 110 – 99.9%Cu (min)
Test Image
Process StepsShear to size6” x 6” (15.2cm x 15.2cm)
DegreaseSolvent clean
CleanHand scrubbed & chemical dip
LaminateHot roll laminator, FX930
ExposeTamarack 161B
DevelopChemcut CC8000
EtchChemcut Model 2315
StripChemcut CC8000
Cross sectionBuehler equipment
MeasureVideo-scope
CalculationsGraph & Analyze
Developing
Chemcut CC8000 Developing SystemAtotech Imagine DS – 1.5% v/vTemperature – 85°F (29.4°C) Spray Pressure – 30psi (2.1 bar) Conveyor Speed – 72ipm (1.8 m/m) Dwell Time – 35 seconds
Model 2315
Etching ParametersEtching Solution – RCE SolutionSpecific Gravity – 42°Be (1.41) Free Acid - ~ 0.6%ORP - ~580mvSpray Pressure – 40psi (2.8 bar) Oscillation Rate – 30spmConveyor Speed – 5.0ipm (12.7 cm/m) Etch Time – 4.0 minutes
Stripping
Chemcut CC8000 Stripping SystemRD-56 from RD Chemicals – 10% solutionTemperature – 130°F (54.4°C) Spray Pressure – 30psi (2.1 bar) Conveyor Speed – 18ipm (45.7 cm/m) Stripping Time – 2.0 minutes
5.0-mil (127µ) line 410 Stainless Steel
Calculations from Measurements
Top Spray Etch Rate (mils/min) 130ºF
0.000.250.500.751.001.251.501.752.002.252.502.75
5.0 7.5 10.0 12.5 15.0
Opening Size (mils)
Etch
Rat
e (m
lis/m
in) Steel
301 SST304 SST316 SST410 SST430 SSTKovarBrassCopper
Top Spray Etch Rate (mils/min) 160ºF
0.000.250.500.751.001.251.501.752.002.252.502.753.003.253.50
5.0 7.5 10.0 12.5 15.0
Opening Size (mils)
Etch
Rat
e (m
ils/m
in) Steel
301 SST304 SST316 SST410 SST430 SSTKovarBrassCopper
Etch Rate Increase – Top Spray Top Etch Rate Increase from 130F to 160F
Opening Size - Mils AverageMaterial 5.0-mils 7.5-mils 10.0-mils 12.5-mils 15.0-mils Increase
Steel 33.1% 30.2% 39.9% 47.3% 46.7% 39.4%301 SST 38.1% 26.7% 20.0% 16.5% 11.4% 22.5%304 SST 51.8% 29.3% 29.9% 30.3% 27.6% 33.8%316 SST 22.3% 35.7% 43.2% 39.6% 41.1% 36.4%410 SST 22.3% 28.7% 32.0% 28.7% 28.1% 28.0%430 SST 33.5% 35.3% 35.4% 37.2% 40.5% 36.4%
Kovar 38.7% 36.4% 45.1% 46.4% 41.9% 41.7%Brass 31.7% 25.0% 28.4% 31.2% 31.3% 29.5%Copper 32.4% 30.4% 33.3% 29.9% 32.6% 31.7%
Bottom Spray Etch Rate (mils/min) 130ºF
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
5.0 7.5 10.0 12.5 15.0
Opening Size (mils)
Etch
Rat
e (m
ils/m
in) Steel
301 SST304 SST316 SST410 SST430 SSTKovarBrassCopper
Bottom Spray Etch Rate (mils/min) 160ºF
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
5.0 7.5 10.0 12.5 15.0
Opening Size (mils)
Etch
Rat
e (m
ils/m
in) Steel
301 SST304 SST316 SST410 SST430 SSTKovarBrassCopper
Etch Rate Increase – Bottom SprayBottom Etch Rate Increase from 130F to 160F
Opening Size - Mils AverageMaterial 5.0-mils 7.5-mils 10.0-mils 12.5-mils 15.0-mils Increase
Steel 27.5% 27.7% 45.0% 29.4% 31.9% 32.3%301SST 48.2% 58.1% 49.3% 45.6% 37.3% 47.7%304SST 19.4% 30.1% 32.1% 25.8% 28.1% 27.1%316SST 39.9% 34.5% 31.9% 40.0% 44.8% 38.2%410SST 34.6% 40.1% 38.1% 37.1% 29.3% 35.8%430SST 43.4% 35.8% 34.4% 34.2% 30.7% 35.7%Kovar 35.8% 34.1% 35.9% 33.2% 35.1% 34.8%Brass 34.1% 31.0% 32.6% 32.3% 30.5% 32.1%
Copper 47.8% 42.1% 44.7% 45.1% 44.5% 44.8%
Typical Etching Trend
5.0 7.5 10.0 12.5 15.0
130F
140F150F
160F
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Etch
Rat
e (m
il/m
in)
Opening Size (mils)
Etch Temperature
Copper Etch Rate - Bottom
Steel Etch RatesAverage Increase - 36.0%, 0.11-mil/10ºF
1.52
1.09 1.12
1.36
0.740.87
0.950.98
1.25
0.921.00
1.16
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
130F 140F 150F 160FEtch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 39.5% Increase
Bottom - 32.4% Increase
301 SST Etch RatesAverage Increase - 33.6%, 0.07-mil/10ºF
1.08
0.93
1.07
0.910.90
0.780.67
0.630.53
0.87
0.770.72
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
130F 140F 150F 160F
Etch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 20.0% Increase
Bottom - 47.2% Increase
304 SST Etch RatesAverage Increase - 31.0%, 0.087-mil/10ºF
1.10
1.361.18
1.031.03
0.830.79
0.730.65
0.99
0.880.84
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
130F 140F 150F 160FEtch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 32.0% Increase
Bottom - 27.7% Increase
316 SST Etch RatesAverage Increase - 37.5%, 0.11-mil/10ºF
1.44
0.91
1.30
1.111.05
0.85
0.750.66
1.181.08
0.930.86
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
130F 140F 150F 160FEtch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom Spray
Average
Top - 37.1% Increase
Bottom - 37.9% Increase
410 SST Etch RatesAverage Increase - 30.5%, 0.10-mil/10ºF
1.48
1.241.16 1.36 1.34
0.730.84
0.950.990.95
1.10 1.15
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
130F 140F 150F 160FEtch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 27.6% Increase
Bottom - 35.6% Increase
430 SST Etch RatesAverage Increase - 36.1%, 0.11-mil/10ºF
0.95
1.04
1.33 1.31
1.42
0.700.77
0.890.87
1.05 1.10 1.19
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
130F 140F 150F 160F
Etch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 36.5% Increase
Bottom - 35.7% Increase
Kovar Etch RatesAverage Increase - 38.1%, 0.11-mil/10ºF
1.341.22
1.110.95
0.980.93
0.84
0.73
1.161.080.98
0.84
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
130F 140F 150F 160F
Etch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 41.1% Increase
Bottom - 34.2% Increase
Brass Etch RatesAverage Increase - 35.0%, 0.21-mil/10ºF
2.872.59
2.282.22
1.981.81
1.61
1.37
2.432.20
1.951.80
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
130F 140F 150F 160FEtch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 29.3% Increase
Bottom - 44.5% Increase
Copper Etch RatesAverage Increase - 31.9%, 0.19-mil/10ºF
2.81
2.38
2.502.46
2.13
1.951.861.64
1.48
2.182.05
1.81
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
130F 140F 150F 160F
Etch Temperature
Etch
Rat
e (m
ils/m
in)
Top SprayBottom SprayAverage
Top - 31.9% Increase
Bottom - 31.8% Increase
Undercut Ratios – Top SprayPre-etch Undercut Comparison as a Ratio of the Vertical Etch
Etch Temp Opening Steel 301 SST 304 SST 316 SST 410 SST 430 SST Kovar Brass Copper5.0-mil 2.0 1.7 2.0 2.6 2.5 2.7 1.7 2.2 2.17.5-mil 2.1 1.9 2.0 2.1 2.8 2.6 1.8 2.3 2.3
130F 10.0-mil 2.2 1.9 2.2 2.1 3.0 2.8 1.9 2.4 2.512.5-mil 2.2 2.1 2.3 2.1 3.2 2.8 1.9 2.4 2.515.0-mil 2.2 2.1 2.3 2.0 2.9 2.7 1.9 2.5 2.5
Average Undercut Ratio 2.14 1.94 2.16 2.18 2.88 2.72 1.84 2.36 2.385.0-mil 2.2 2.1 2.2 2.1 2.6 2.4 1.9 2.0 2.17.5-mil 1.9 2.1 2.3 2.4 2.6 2.5 2.0 2.1 2.1
160F 10.0-mil 2.0 2.1 2.4 2.5 2.7 2.9 2.1 2.1 2.212.5-mil 2.4 2.3 2.8 2.5 2.8 2.8 2.2 2.6 2.115.0-mil 2.3 2.2 2.4 2.5 2.4 3.2 2.2 2.3 2.4
Average Undercut Ratio 2.16 2.16 2.42 2.40 2.62 2.76 2.08 2.22 2.18
Undercut Ratios – Bottom Spray
Pre-Etch Undercut Comparison as a Ratio of the Vertical EtchEtch Temp Opening (u) Steel 301SST 304SST 316SST 410SST 430SST Kovar Copper Brass
5.0-mil 2.8 1.2 1.4 1.5 2.3 1.9 1.4 2.7 2.87.5-mil 2.9 1.4 1.6 1.6 2.6 2.1 1.7 3.2 3.0
130F 10.0-mil 3.6 1.3 1.8 1.9 3.0 2.4 1.7 3.4 3.112.5-mil 2.7 1.4 2.0 2.0 3.0 2.5 1.8 3.4 3.115.0-mil 2.8 1.4 1.8 1.8 3.0 2.3 1.7 3.2 3.1
Average Undercut Ratio 3.0 1.3 1.7 1.8 2.8 2.2 1.7 3.2 3.05.0-mil 2.4 1.8 3.0 2.3 2.7 2.2 2.0 2.7 2.57.5-mil 2.5 2.0 2.7 2.5 3.0 2.4 2.2 2.7 2.5
160F 10.0-mil 2.6 2.2 2.9 2.8 3.2 2.6 2.4 2.8 2.612.5-mil 2.8 2.3 3.0 2.7 3.3 2.7 2.3 2.8 2.815.0-mil 3.0 2.1 3.0 2.9 3.2 2.7 2.4 2.9 2.8
Average Undercut Ratio 2.7 2.1 2.9 2.6 3.1 2.5 2.3 2.8 2.6
Steel Undercut Ratios
2.16
2.66
2.362.14
2.04 2.02
2.44
2.32
2.95
2.222.22
2.52
0
0.5
1
1.5
2
2.5
3
3.5
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 2.33
St. Dev. - 0.10
301 SST Undercut Ratios
2.09
2.162.141.961.94
1.34
1.601.74
1.941.731.67
0
0.5
1
1.5
2
2.5
3
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 1.86 St. Dev. - 0.19
304 SST Undercut Ratios
2.16 2.20
2.562.66
2.92
2.48
2.14
1.72
2.76
1.96
0
0.5
1
1.5
2
2.5
3
3.5
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 2.33
St. Dev. - 0.36
316 SST Undercut Ratios
2.402.20
1.94
2.18
2.642.54
2.06
1.76
2.51
1.991.96
2.31
0
0.5
1
1.5
2
2.5
3
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 2.19
St. Dev. - 0.26
410 SST Undercut Ratios
2.62
3.08
2.742.872.88
2.642.88
3.082.80
2.78
0
0.5
1
1.5
2
2.5
3
3.5
4
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAvergae
Average - 2.83
St. Dev. - 0.07
430 SST Undercut Ratios
2.522.662.762.72 2.66 2.70
2.442.24
2.522.50
0
0.5
1
1.5
2
2.5
3
3.5
4
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 2.58
St. Dev. - 0.08
Kovar Undercut Ratios
2.082.02
1.781.84
2.26
1.621.66
2.16
1.691.76
0
0.5
1
1.5
2
2.5
3
130F 140F 150F 160FEtch temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 1.89
St. Dev. - 0.21
Brass Undercut Ratios
2.22
2.64
2.302.18
2.36
3.063.203.02
2.48
2.702.652.64
0
0.5
1
1.5
2
2.5
3
3.5
4
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 2.62
St. Dev. - 0.10
Copper Undercut Ratios
2.18
2.782.60
2.102.26
2.38
2.862.86
3.18
2.60 2.502.70
0
0.5
1
1.5
2
2.5
3
3.5
4
130F 140F 150F 160F
Etch Temperature
Und
ercu
t Rat
ios
Top SprayBottom SprayAverage
Average - 2.60
St. Dev. - 0.08
FindingsEtch rate increases with temperature increaseSteel alloys – 34.0% to 36.0%
~ 0.1-mil for each 10º FCopper alloys – 32.0% to 35.0%
~ 0.2-mil for each 10º FNo appreciable effect on undercut ratioSteel alloys – 2.3 averageCopper alloys – 2.6 average
Discussion
Footprint – EqualThroughput – 30% to 40% morePerformance – Equal to PVC equipmentCost – More than PVC equipmentLife expectancy – Could be less
High Temperature Ferric Chloride Etching
An Evaluation of the Process
Randy MarkleChemcut