This document provides a status report on copper electroforming. It describes the copper electroforming process, which involves depositing copper onto a mandrel that is later removed. The objectives of the work include optimizing process parameters, producing parts with complex geometries, monitoring parameters during electroforming, measuring radiopurity, and improving the process chemically and electrolytically. Progress includes determining optimum parameters for smooth surfaces and homogeneous deposition, electroforming hexagonal and cylindrical parts, developing a system to measure process parameters, and conducting preliminary radiopurity measurements of an electroformed part.

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