1. Copper Electroforming
Status Report
Silvia Borjabad
7th JRA-1 Meeting Zaragoza (November 2007)

2. OUTLINE
 Copper Electroforming Process
 Review of objectives and work progress
 Summary and prospects
S. Borjabad 7th JRA-1 Zaragoza Nov´07

3. Copper Electroforming Process
Electroforming is a method of producing pieces by the deposition
of a metal onto a mold (mandrel) which is subsequently removed
Copper Electroforming Overview
ENGINE
• High-purity copper parts
TANK
• Accurate surface
FILTER reproduction
• Underground process
• Chemical & electrolitic
improvements
CuSO 4 PUMP
H 2SO4
S. Borjabad 7th JRA-1 Zaragoza Nov´07

4. Copper Electroforming Process
Process Parameters & Key Elements
• Mandrel turns during the whole process
producing a homogeneous deposition
Constituents of the Electrolyte
• Electrolyte circulates with continuous
Constituent Concentration
filtration to eliminate impurities
• Covered bath avoids air and dust CuSO4 . 5H2O 188 g/l
contamination H2SO4 75 g/l
• Plating is done over polished and cleaned HCl 30 mg/l
stainless steel mandrels with the same Thiourea 3 mg/l
shape of the relevant copper parts
(Brodzinski et al.,A292 (1990) 337)
• H2SO4 improves the electric conductivity
• HCl and Thiourea affect copper crystal
nucleation and grain size
S. Borjabad 7th JRA-1 Zaragoza Nov´07

5. Copper Electroforming Process
Electroforming Set-Up
Voltage Supply
Electronic
Control System
• Rotation Speed & Direction
Electrolitic Bath
• Plating modes
• Electrolyte circulation
• Inert cover gas (N2)
Temperature
and pH sensors
• Temperature & pH sensors
• Parameters DAQ system
Filter and Pump
S. Borjabad 7th JRA-1 Zaragoza Nov´07

6. 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

7. Review of objectives and work progress
Electroforming Process Parameter Tuning
Smooth surface
Goals Homogeneous copper distribution
Without periodic machining process
Parameters: Current Density, Speed Rotation and Direction Rotation
Optimum parameters: 3 A/dm2, 2 rev/s, forward-reverse rotation
S. Borjabad 7th JRA-1 Zaragoza Nov´07

8. Review of objectives and work progress
Electroformed copper parts with complex geometry
• Hexagonal & cylindrical electroformed copper parts
• Smooth
Isolated areas surface
with Teflon,
parafine or • Accurate
silicone surface
reproduction
(corners)
1.5 mm of thickness
• Electroformed copper part for PMT encapsulation (collaboration ANAIS)
• Smooth surface
Isolated
h
wit gress
• Homogeneous
areas with
s o
est distribution
Teflon
t rp
e ing g in Final machining
r in •
old rm
S fo process
r o
Complex mandrel Auxiliary
el ect 1.5-2 mm of thickness
anode
S. Borjabad 7th JRA-1 Zaragoza Nov´07

9. 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

10. Review of objectives and work progress
Parameters monitorization during the electroforming
Current (I)
Electroforming Evolution during the process
Parameters Voltage between electrodes (ΔV)
Electrolyte properties
Electrolyte Temperature & pH
Temperature &
pH sensors DAQ software
Parameters
measurement system
S. Borjabad 7th JRA-1 Zaragoza Nov´07

11. 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

12. Review of objectives and work progress
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).
Radionuclide Units (mBq/kg)
Th series 212
Pb ≤ 16
A standard- electroformed copper part
(commercial chemicals & at sea level) 228
Ac ≤ 25
U series 234
Th ≤ 32
Copper mass: 161 g
234
Pa ≤ 90
Measuring time: 5 d
≤e
ss
226
Ra gr24
pro
t in ≤3
214
Pb
214 m
en
ure
Bi ≤6
m eas 235U ≤ 1.4
w
Ne 137
Cs ≤7
40
K ≤ 90
60
Co ≤7
Copper part into a Copper around the 56
Co ≤3
Marinelli container HPGe detector 57
Co ≤8
S. Borjabad 7th JRA-1 Zaragoza Nov´07 (Data Analysis courtesy J. Puimedon)
58 ≤5
Co

13. Review of objectives and work progress
 Electroforming process parameter tuning
 Electroformed copper parts with complex geometry
 Monitorization of parameters during the electroforming process
ess
rogrRadiopurity measurements of electroformed copper parts
In p
 Chemical & electrolytic improvements
eps
N ext st
 Electroforming in steps to fabricate cryostat copper components
S. Borjabad 7th JRA-1 Zaragoza Nov´07

14. Summary and Prospects
SUMMARY
 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.
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