D. Cheng

Sept 23, 2013

Instrumentation Trace Material Selection

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Outline

9/23/13

• Current LARP trace production• Issues experienced• Other materials available

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LARP Coil Instrumentation

9/23/13

Stainless Laminate Adhesive*

Polyimide (Apical AV)

Additional Kapton**

TQ/LQ 304 / 25 µm 15 µm 25 µm -

HQ Coils 1-10 304 / 25 µm 15 µm 25 µm -

HQ Coils 11-14 304 / 25 µm 15 µm 25 µm 25 µm

HQ Coils 15-21 304 / 25 µm 15 µm 25 µm 50 µm

HQ Coils 22-26 304 / 25 µm 15 µm 25 µm 25 µm

LHQ 304 / 25 µm 15 µm 25 µm 50 µm

*Modified cross-linked epoxy system, AS 1084** Joined by single strip of 3M VHB F-9460PC

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Instrumentation Trace Fabrication Process

9/23/13

• Design and print artwork (negative mask) • Cut trace laminated material to length• Cover conductive laminate with resist• Expose resist under negative mask with UV light• Wash the uncured resist from laminate• Etch laminated material with cured resist

pattern– Conductive layer covered by resist remains

• Remaining resist washed off by stripping agent

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Instrumentation Trace Impreg. Preparations

9/23/13

• Electrical QA• Bond additional layer of Kapton– 25 µm (earlier iterations)– 50 µm (current)

• Perforate polyimide layers• Install during coil impregnation

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Experiences with Traces During Coil Fabrication

9/23/13

• “Pinholes” have caused electrical failures– A few were caused by materials– Some were caused by the handling

• Additional layers (25 µm or 50 µm) of Kapton were added for protection– Some laminated traces did not fully impregnate

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Pinholes

9/23/13

Material flaw (inclusion) that caused a hipot failure during electrical QA

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Impregnation Between Polyimide Layers

9/23/13

Coil 14 OL, end of ramp area, post-impregnation, sectioned

Coil 14 OL, end of ramp area, trace peeled off

Lack of fill between layers Coil itself shows good impregnation

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Potential Heater/Instrumentation Materials

9/23/13

• Current trace designs specify 50 µm thick polyimide backing, therefore the following options exist:

Conductor Laminate Adhesive*

Polyimide Polyimide Thickness

GTS, Apical AV 316 SS / 25 µm 15 µm Apical AV** 25 µm

GTS, Kapton MT 316 SS / 25 µm 15 µm Kapton MT 25 µm

Dupont Pyralux AP (25)

Cu / 25 µm - Pyralux AP (Polyimide)

25 µm

GTS, Apical AV 316 SS / 25 µm 15 µm Apical AV** 50 µm

GTS, Kapton MT 316 SS / 25 µm 15 µm Kapton MT 50 µm

DuPont Pyralux AP (50)

Cu / 25 µm - Pyralux AP (Polyimide)

50 µm

*Modified cross-linked epoxy system, AS 1084**Apical AV is similar in thermal conductivity as Kapton HN (0.19 W/mK)

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Materials Options Summary

9/23/13

Pros Cons Notes

25 µm thick polyimide trace materials

Additional layer of polyimide protects against material flaws

Entire laminate may not impregnate well;Unknown epoxy layer thickness after impregnation

Requires additional 25 µm layer of polyimide

50 µm thick polyimide trace materials

Improved impregnation due to single layer of material

Does not inherently provide protection from material flaws

Does not require additional layer of polyimide

Copper trace materials (Pyralux AP)

One less layer between heater and conductor; polyimide is 0.26 W/mK @ ~RT

Unknown performance (SS only has been used in LARP)

No adhesive layer between copper and polyimide (directly bonded)

Kapton MT 0.37 W/mK (3x Kapton HN equiv. at ~RT)

Unknown performance (has not been tested)

Same laminate bonding process as SS materials

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Additional Slides

9/23/13