Silvia Borjabad

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

• Copper Electroforming Process

• Review of objectives and work progress

• Summary and prospects

S. Borjabad 7th JRA-1 Zaragoza Nov07
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Copper Electroforming Process
Electroforming is a method of producing pieces by
the deposition of a metal onto a mold (mandrel)
which is subsequently removed

• High-purity copper parts
• Accurate surface reproduction
• Underground process
• Chemical electrolitic improvements

S. Borjabad 7th JRA-1 Zaragoza Nov07
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Copper Electroforming Process
Process Parameters Key Elements

• 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)
S. Borjabad 7th JRA-1 Zaragoza Nov07
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Copper Electroforming Process
Electroforming Set-Up
Voltage Supply
Electronic Control System
Electrolitic Bath
Temperature and pH sensors
Filter and Pump
S. Borjabad 7th JRA-1 Zaragoza Nov07
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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 Nov07
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Review of objectives and work progress
Electroforming Process Parameter Tuning
Smooth surface Homogeneous copper
distribution Without periodic machining process
Goals
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 Nov07
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Review of objectives and work progress
Electroformed copper parts with complex geometry

• Hexagonal cylindrical electroformed copper
  parts

• Smooth surface
• Accurate surface reproduction (corners)

Isolated areas with Teflon, parafine or silicone
1.5 mm of thickness

• Electroformed copper part for PMT encapsulation
  (collaboration ANAIS)

• Smooth surface
• Homogeneous distribution
• Final machining process

Isolated areas with Teflon
Soldering tests with electroforming in progress
Complex mandrel
Auxiliary anode
1.5-2 mm of thickness
S. Borjabad 7th JRA-1 Zaragoza Nov07
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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 Nov07
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Review of objectives and work progress
Parameters monitorization during the
electroforming
Current (I) Voltage between electrodes
(?V) Electrolyte Temperature pH
Evolution during the process
Electroforming Parameters
Electrolyte properties
Temperature pH sensors
DAQ software
Parameters measurement system
S. Borjabad 7th JRA-1 Zaragoza Nov07
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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 Nov07
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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).
A standard- electroformed copper part (commercial
chemicals at sea level)
Copper mass 161 g Measuring time 5 d
New measurement in progress
Copper part into a Marinelli container
Copper around the HPGe detector
(Data Analysis courtesy J. Puimedon)
S. Borjabad 7th JRA-1 Zaragoza Nov07
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Review of objectives and work progress

• Electroforming process parameter tuning

• Electroformed copper parts with complex geometry

• Monitorization of parameters during the
  electroforming process

In progress
Radiopurity measurements of electroformed copper
parts

• Chemical electrolytic improvements

Next steps

• Electroforming in steps to fabricate cryostat
  copper components

S. Borjabad 7th JRA-1 Zaragoza Nov07
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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 Nov07