Silvia Borjabad
Copper Electroforming
7th JRA-1 Meeting Zaragoza (November 2007)
Status Report
OUTLINE
Copper Electroforming Process
Review of objectives and work progress
Summary and prospects
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Copper Electroforming Process
Electroforming is a method of producing pieces by the deposition of a metal onto a mold (mandrel) which is subsequently removed
PUMP
ENGINE
FIL
TE
RTANK
SOCuSO4
H2 4
Copper Electroforming Overview
PUMP
ENGINE
FIL
TE
RTANK
SOCuSO4
H2 4SOCuSO4
H2 4
CuSO4
H2 4
Copper Electroforming Overview
• High-purity copper parts
• Accurate surface reproduction
• Underground process
• Chemical & electrolitic improvements
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Process Parameters & Key Elements
Constituent Concentration
CuSO4 . 5H2O 188 g/l
H2SO4 75 g/l
HCl 30 mg/l
Thiourea 3 mg/l
• Mandrel turns during the whole process producing a homogeneous deposition
• Electrolyte circulates with continuous filtration to eliminate impurities
• Covered bath avoids air and dust contamination
• Plating is done over polished and cleaned stainless steel mandrels with the same shape of the relevant copper parts
• H2SO4 improves the electric conductivity
• HCl and Thiourea affect copper crystal nucleation and grain size
Constituents of the Electrolyte
(Brodzinski et al.,A292 (1990) 337)
Copper Electroforming Process
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Filter and Pump
Electrolitic Bath
Voltage SupplyElectronic
Control System
Temperature and pH sensors
Electroforming Set-Up
Copper Electroforming Process
• Electrolyte circulation
• Inert cover gas (N2)
• Rotation Speed & Direction
• Plating modes
• Temperature & pH sensors
• Parameters DAQ system
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Review of objectives and work progress
Electroforming process parameter tuning
Electroformed copper parts with complex geometry
Monitorization of parameters during the electroforming process
Radiopurity measurements of electroformed copper parts
Chemical & electrolytic improvements
Electroforming in steps to fabricate cryostat copper components
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Electroforming Process Parameter Tuning
Optimum parameters: 3 A/dm2, 2 rev/s, forward-reverse rotation
Parameters: Current Density, Speed Rotation and Direction Rotation
Review of objectives and work progress
Goals
Smooth surface
Homogeneous copper distribution
Without periodic machining process
S. Borjabad 7th JRA-1 Zaragoza Nov´07
• Electroformed copper part for PMT encapsulation (collaboration ANAIS)
• Hexagonal & cylindrical electroformed copper parts
Isolated areas with Teflon, parafine or
silicone
• Smooth surface
• Accurate surface reproduction (corners)
1.5 mm of thickness
Electroformed copper parts with complex geometry
Review of objectives and work progress
Complex mandrel
• Smooth surface
• Homogeneous distribution
• Final machining process
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Auxiliary anode
Isolated areas with
Teflon
1.5-2 mm of thickness
Soldering tests with
electroforming in progress
Review of objectives and work progress
Electroforming process parameter tuning
Electroformed copper parts with complex geometry
Monitorization of parameters during the electroforming process
Radiopurity measurements of electroformed copper parts
Chemical & electrolytic improvements
Electroforming in steps to fabricate cryostat copper components
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Parameters monitorization during the electroforming
Review of objectives and work progress
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Temperature & pH sensors DAQ software
Parameters measurement system
Electroforming Parameters
Current (I)
Voltage between electrodes (ΔV)
Electrolyte Temperature & pH
Evolution during the process
Electrolyte properties
Review of objectives and work progress
Electroforming process parameter tuning
Electroformed copper parts with complex geometry
Monitorization of parameters during the electroforming process
Radiopurity measurements of electroformed copper parts
Chemical & electrolytic improvements
Electroforming in steps to fabricate cryostat copper components
S. Borjabad 7th JRA-1 Zaragoza Nov´07
Radionuclide Units (mBq/kg)
Th series 212Pb ≤ 16
228Ac ≤ 25
U series 234Th ≤ 32
234Pa ≤ 90
226Ra ≤ 24
214Pb ≤ 3
214Bi ≤ 6
235U ≤ 1.4
137Cs ≤ 7
40K ≤ 90
60Co ≤ 7
56Co ≤ 3
57Co ≤ 8
58Co ≤ 5
Preliminary radiopurity measurement of electroformed copper The levels of radiopurity in an electroformed copper part were previously measured with a HPGe detector (1Kg Ge) at the Canfranc Underground Laboratory (LSC).
Copper mass: 161 g
Measuring time: 5 d
Copper part into a Marinelli container
Copper around the HPGe detector
A standard- electroformed copper part (commercial chemicals & at sea level)
(Data Analysis courtesy J. Puimedon)
Review of objectives and work progress
S. Borjabad 7th JRA-1 Zaragoza Nov´07
New measurement in progress
Review of objectives and work progress
Electroforming process parameter tuning
Electroformed copper parts with complex geometry
Monitorization of parameters during the electroforming process
Radiopurity measurements of electroformed copper parts
Chemical & electrolytic improvements
Electroforming in steps to fabricate cryostat copper components
S. Borjabad 7th JRA-1 Zaragoza Nov´07
In progress
Next steps
Summary and Prospects
Electroformed copper parts with smooth surface and without machining can be manufactured by means of the tuning of process parameters.
Copper parts with different geometry (hexagonal, cylindrical) can be achieved by easy modifications.
Radiopurity measurements of electroformed copper parts are in progress.
Soldering tests to join copper parts with electroformed copper are in progress.
SUMMARY
PROSPECTS Chemical & electrolitic improvements: CuSO4 purified by recrystallization,
high- purity acids and anodes, CoSO4 and BaSO4 to reduce Co and Ra isotopes.
Electroforming in steps to fabricate different copper parts such as cryostat components.
This facility will be installed at the new (enlarged) Canfranc Underground Laboratory as soon as the clean room is ready.
S. Borjabad 7th JRA-1 Zaragoza Nov´07
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