Table B.1 238U and 232Th concentrations at each cable fabrication step for raw materials, photolithography solutions, and representative coupons. Measurements of the materials and solutions are normalized to their individual component masses, while the values listed for the coupons are normalized to the mass of the coupon, including all layers present, at that step. ∗Laminate and coverlay from Taiflex (2FPDR2005JA and FHK1025, respectively). †Photoresist from DuPont (Riston MM500)
Fabrication step | Materials | Solutions | Coupons | ||||
|---|---|---|---|---|---|---|---|
238U [pg/g] | 232Th [pg/g] | 238U [pg/g] | 232Th [pg/g] | 238U [pg/g] | 232Th [pg/g] | ||
1 | Laminate∗ | 9 ± 4 | 8 ± 6 | ||||
2 | Cut and Drill | <16 | <20 | ||||
3 | Copper Plating | 140 ± 10 | <20 | ||||
4 | Sanding | 190 ± 20 | 240 ± 110 | ||||
5 | Developing | 19 ± 13† | 8 ± 6† | 2630 ± 110 | 6 ± 2 | 530 ± 40 | 210 ± 10 |
6 | Etching | 2300 ± 200 | 80 ± 10 | 2600 ± 600 | 150 ± 40 | ||
7 | Stripping | 1510 ± 70 | 22 ± 2 | 4400 ± 500 | 120 ± 30 | ||
8 | Coverlay* | 18,000 ± 2000 | 1600 ± 140 | 7400 ± 200 | 710 ± 20 | ||
9 | Microetching | 1060 ± 60 | 1090 ± 60 | 7400 ± 400 | 730 ± 50 | ||
10 | ENIG Processing | 7300 ± 200 | 750 ± 40 | ||||