1. Status of Al-FPC development for IB A. Di Mauro, A. Junique, P. Riedler ITS-MFT mini-week 11.03.2014

2. Updated layout 11/03/2014ITS-MFT mini-week - Al-FPC - A. Di Mauro2 AGNDDGND AVDDDVDD 3.5 mm 100 µm 75 µm POLYIMIDE 25 µm ALUMINIUM ~ 10 µm SOLDER MASK 4 mm 11 mm Changes wrt TDR version: Polyimide thickness -> 75  m ~ 90  diff. impedance (estimated using Apical NP dielectric constant) Deeper holes (150  m) better for laser soldering Larger holes 220  m, better for laser soldering Solder mask coverlay, applied by spraying, all gaps are filled avoiding air bubbles formation (observed in PI coverlays).

3. High-speed differential lines MLVDS differential lines Signals connections 1 1 2 UEC5 connector (contacts layout not yet implemented) 15 mm to be determined Extension for connection to service cables

4. Al-FPC on service cable

5. AVDD DVDD 2 Power connections Solder connections Flex extension AVDD & DVDD AGND & DGND 15 mm Extension for connection to services

6. EoC raw and FPC width 11/03/2014 6 ITS-MFT mini-week - Al-FPC - A. Di Mauro 1.25 0.2 0.1 0.2 0.15 0.1 FPC edge Differential lines chip edge 0.55 (distance of EoC pad axis to chip edge) 0.7 (FPC extra width) FPC pad common distribution of DCTRL and DCLK OK for integration!

7. Al-FPC production procedure Main steps of procedure developed at CERN for STAR flex production (@ LERMPS (F)) : 1) Preparation of polyimide (Apical NP) substrate : – Thermal cycle (12 h at 180 o C) to induce max shrinking (new, under test) – Holes drilling by laser – Sand-blasting + outgassing 2) Deposition of Al layer (25  m) (performed by DEPHIS (F), FHR (DE)): – Plasma cleaning – Pump down to 10 -5 mbar – Cr film coating – Al sputtering (~ 10 h, in several steps to avoid overheating) 3) Chemical etching @ CERN ( Laser etching tests by Swiss Micro Laser) 4) Coverlay (solder mask) + Ni/Au @ CERN 7 11/03/2014ITS-MFT mini-week - Al-FPC - A. Di Mauro

8. Summary of production tests Supplier/sample datecomments FHR/ 15 and 25  m Oct 2013 Presence of small fibres embedded in the Al, small metallic bubbles on the surface, presence of black layer under the Al film, chemical etching was tried on 15  m Al and didn’t work (material too dense). After that: CERN recipe transferred to FHR 11/03/20148ITS-MFT mini-week - Al-FPC - A. Di Mauro

9. FHR samples #1 11/03/20149ITS-MFT mini-week - Al-FPC - A. Di Mauro

10. Summary of production tests Supplier/sample datecomments FHR/ 15 and 25  m Oct 2013 Presence of small fibres embedded in the Al, small metallic bubbles on the surface, presence of black layer under the Al film, chemical etching was tried on 15  m Al and didn’t work (material too dense). After that: CERN recipe transferred to FHR DEPHIS/ 15 and 25  m Dec 2013 Al aspect not perfect, chemical etching ~OK, solder mask coverlay ~OK, Ni/Au deposition didn’t work (zincate attached and dissolved Al under the coverlay). Reasons: DEPHIS didn’t copy exactly the procedure from LERMPS (polarisation of PI foil during coating, …) 11/03/201410ITS-MFT mini-week - Al-FPC - A. Di Mauro

11. DEPHIS samples 11/03/201411 After etching, w/o coverlay with coverlay ITS-MFT mini-week - Al-FPC - A. Di Mauro

12. Summary of production tests Supplier/sample datecomments FHR/ 15 and 25  m Oct 2013 Presence of small fibres embedded in the Al, small metallic bubbles on the surface, presence of black layer under the Al film, chemical etching was tried on 15  m Al and didn’t work (material too dense). After that: CERN recipe transferred to FHR DEPHIS/ 15 and 25  m Dec 2013 Al aspect not perfect, chemical etching ~OK, solder mask coverlay ~OK, Ni/Au deposition didn’t work (zincate attached and dissolved Al under the coverlay. Reasons: DEPHIS didn’t copy exactly the procedure from LERMPS (polarisation of PI foil during coating, …) FHR/ 15 and 25  m Jan 2014 15  m done on PI prepared at CERN, 25  m done on PI prepared by FHR; Al aspect improved, however when testing with zincate Al reacted and lost adherence to PI. Etching was not tried. 11/03/201412ITS-MFT mini-week - Al-FPC - A. Di Mauro

13. FHR samples #2 11/03/201413 reaction to zincate After Ni/Au: easy peel-off of Al, impossible to use for FPC pads ! ITS-MFT mini-week - Al-FPC - A. Di Mauro

14. Summary of production tests Supplier/ datecomments FHR/ 15 and 25  m Oct 2013 Presence of small fibres embedded in the Al, small metallic bubbles on the surface, presence of black layer under the Al film, chemical etching was tried on 15  m Al and didn’t work (material too dense). After that: CERN recipe transferred to FHR DEPHIS/ 15 and 25  m Dec 2013 Al aspect not perfect, chemical etching ~OK, solder mask coverlay ~OK, Ni/Au deposition didn’t work (zincate attached and dissolved Al under the coverlay. Reasons: DEPHIS didn’t copy exactly the procedure from LERMPS (polarisation of PI foil during coating, …) FHR/ 15 and 25  m Jan 2014 15  m done on PI prepared at CERN, 25  m done on PI prepared by FHR; Al aspect improved, however when testing with zincate Al reacted and lost adherence to PI. Etching was not tried. LERMPS/ 25  m Feb 2014 Zincate test OK, 6 FPC under processing DEPHIS/ 25  m Feb 2014 Zincate test OK on small sample, 15 FPC production just launched 11/03/201414ITS-MFT mini-week - Al-FPC - A. Di Mauro

15. Laser etching tests Using sample from FHR (not compatible with chemical etching!) 15 11/03/2014ITS-MFT mini-week - Al-FPC - A. Di Mauro IR laserUV laser Traces section not yet optimal (trapezoidal), further tests ongoing

16. Metrology checks -Polyimide shrinking on first exposure to high T: APICAL NP -> 0.04% @150 o C for 0.5 h, 0.08% @ 200 o C for 2 h -Al-FPC production requires various thermal cycles: -Outgassing: 180 o C -Al sputtering : 90-130 o C -Image transfer: 80 o C -Solder mask: 180 o C -Metrology check to measure induced “shrinking”: distance between first and last contact along trace lines (nominal 268.8) 11/03/201416ITS-MFT mini-week - Al-FPC - A. Di Mauro

17. Metrology checks avg shrinking = 0.49 (~ 0.2 %) (should be corrected by initial thermal stabilization process) st. dev. = 0.07 (statistics too small) 11/03/201417 samplestageresults DEPHISbefore solder mask 5 lines of same FPC: 268.562, 268.575, 268.545, 268.565, 268.528 AVG= 268.56, STDEV=0.019 FHRbefore etching 5 lines of same FPC: 268.405, 268.396, 268.379, 268.366, 268.384 AVG= 268.39, STDEV=0.015 DEPHISbefore Ni/Au 2 lines of 5 different FPCs: - 268.387 268.357 - 268.238 268.279 - 268.345 268.368 - 268.228 268.246 - 268.300 268.318 AVG 268.3 268.32 STDEV 0.07 0.052 ITS-MFT mini-week - Al-FPC - A. Di Mauro

18. Eye diagram 11/03/2014ITS-MFT mini-week - Al-FPC - A. Di Mauro18 FPC in Cu, 50  m polyimide ~ 90  impedance (similar to Al FPC with 75  m polyimide) 1.5 Gbit/s (by M. Keil and A. Junique)

19. Next steps Validation of chemical etching on LERMPS and DEPHIS FPCs, 6 + 15 prototypes in production Systematic dimensional control of FPC on all new production from DEPHIS, validate thermal stabilisation; if needed, try compensation of shrinking by modified hole positions in layout Finalize tests with laser etching and get a quotation from Swiss Micro Laser Launch pre-series production for IB full prototype 11/03/201419ITS-MFT mini-week - Al-FPC - A. Di Mauro