RRR and thickness measurements of Cu plating Hiroaki Umezawa, Futoshi Saito Tokyo Denkai Co., Ltd. Eiji Kako KEK

Contents Background RRR Measurement Method of Cu Plating Thickness Measurement of Cu Plating RRR Measurement result Summary

Background Material for Input coupler Low thermal conductivity is required to suppress heat transfer from outside of cryostat. High electric conductivity (i.e. low resistance) is required to suppress RF resistance. ↓ Very thin copper plated SUS (0.8mm) Evaluation of electric conductivity and thermal conductivity of the cu plating is necessary. RRR measurement of Cu plating (Target value 30-60) クライオスタット外からの熱侵入(Static Loss)を抑えるため、熱伝導率が低い材質が望ましい。 Low thermal conductivity is required to suppress heat transfer from outside of cryostat. 高周波損失(Dynamic Loss)を抑えるため、電気伝導度の高い(i.e. 低抵抗)材質が望まれる。 High electric conductivity is required to suppress RF resistance. 極薄銅メッキSUS（0.8t） Very thin cupper plated SUS (0.8mm) 銅メッキの電気伝導度評価が必要 Evaluation of electric conductivity of the cu plate is necessary. 銅メッキのRRR測定（RRR30〜60目標） RRR measurement of Cu plating (Target value 30-60)

RRR Measurement System

How to calculate RRR of the Cu plating tSUS S2=W・tSUS S3=W・tCu S1=W・tCu/SUS tCu tCu/SUS Combined Resistance Subtract Rsus from Rcu/sus Rcu/sus minas Rsus is Rcu. L 1 mm ρCu ρSUS ρCu/SUS W 5mm

Sample preparation During the input coupler production, heat history of 800C will be added in hydrogen atmosphere due to the brazing. To research the influence of this heat treatment(HT), we prepared 2 types of samples which are heat treated and not heat treated. #Simulation of brazing condition. 3 samples from each types are prepared, 2 samples for RRR measurement, 1 sample for Cu plating thickness measurement.

Sample

Sample サンプルサイズ　110x5xt

The copper is melted by HN03 Cu remove The copper is melted by HN03 硫酸で銅を溶かす。 The copper is melted by HN03　(Nitric Acid) Au Strike Ni Strike

Digital Micro Scope

Plating Thickness Measurement Sample A: 18um Sample B: 3um

Measurement Result of Plating Thickness

Thickness of Cu Plating

RRR Measurement Result C F H H G E B D C G A D B F E

RRR Measurement Result C F H G H E B D C G A D B F E

RRR Measurement Result C F H G H E B D C G A D B F E

Conclusion RRR measurement and Cu plating thickness measurement of SUS used for material of input coupler of SC Cavity was done. There is a difference between measured plating thickness by us and nominal plating thickness by plating vender. To get high RRR, plating thickness is important. 800C heat treatment exert a negative effect on RRR of plating. To overcome the bad influence from heat treatment, thickness of the plating must have at least 30 micrometer. 公称：nominal

Resistivity Cu Plated SUS Naked SUS

Thickness of Cu Plating Before and After Heat Treatment