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Status of Al-FPC development for IB
A. Di Mauro, A. Junique, P. RiedlerITS-MFT mini-week 11.03.2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro 2
Updated layout
11/03/2014
AGND DGND
AVDD DVDD
3.5 mm 100 µm 100 µm
75 µm POLYIMIDE
25 µm ALUMINIUM
25 µm ALUMINIUM
~ 10 µm SOLDER MASK
~ 10 µm SOLDER MASK
4 mm
4 mm
11 mm
Changes wrt TDR version:• Polyimide thickness -> 75
mm• ~ 90 W diff. impedance
(estimated using Apical NP dielectric constant)
• Deeper holes (150 mm) better for laser soldering
• Larger holes 220 mm, better for laser soldering
• Solder mask coverlay, applied by spraying, all gaps are filled avoiding air bubbles formation (observed in PI coverlays).
AVDD
DVDD
DGND
AGND
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
Al-FPC
on service cable
AVDD
DVDD
2
Power connections Solder connections
Flex extension
AVDD & DVDD
AGND & DGND
15
mm
Extension for connection to services
EoC raw and FPC width
11/03/20146
ITS-MFT mini-week - Al-FPC - A. Di Mauro
1.2
5
0.2
0.10.10.10.1
0.2
0.15
0.10.10.1
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!
ITS-MFT mini-week - Al-FPC - A. Di Mauro
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 oC) to induce max shrinking (new, under test)– Holes drilling by laser– Sand-blasting + outgassing
2) Deposition of Al layer (25 mm) (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
711/03/2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro 8
Summary of production tests
Supplier/sample date
comments
FHR/ 15 and 25 mm 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 mm Al and didn’t work (material too dense) . After that: CERN recipe transferred to FHR
11/03/2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro 9
FHR samples #1
11/03/2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro 10
Summary of production tests
Supplier/sample date
comments
FHR/ 15 and 25 mm 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 mm Al and didn’t work (material too dense) . After that: CERN recipe transferred to FHR
DEPHIS/ 15 and 25 mm 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, …)
11/03/2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro 11
DEPHIS samples
11/03/2014
After etching, w/o coverlay
with coverlay
ITS-MFT mini-week - Al-FPC - A. Di Mauro 12
Summary of production tests
Supplier/sample date
comments
FHR/ 15 and 25 mm 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 mm Al and didn’t work (material too dense) . After that: CERN recipe transferred to FHR
DEPHIS/ 15 and 25 mm 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 mm Jan 2014
15 mm done on PI prepared at CERN, 25 mm 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.
11/03/2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro 13
FHR samples #2
11/03/2014
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/ date comments
FHR/ 15 and 25 mm 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 mm Al and didn’t work (material too dense) . After that: CERN recipe transferred to FHR
DEPHIS/ 15 and 25 mm 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 mm Jan 2014
15 mm done on PI prepared at CERN, 25 mm 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 mmFeb 2014
Zincate test OK, 6 FPC under processing
DEPHIS/ 25 mmFeb 2014
Zincate test OK on small sample, 15 FPC production just launched11/03/2014
ITS-MFT mini-week - Al-FPC - A. Di Mauro
Laser etching testsUsing sample from FHR (not compatible with chemical etching!)
1511/03/2014
IR laser UV laser
Traces section not yet optimal (trapezoidal), further tests ongoing
ITS-MFT mini-week - Al-FPC - A. Di Mauro 16
Metrology checks- Polyimide shrinking on first exposure to high T: APICAL NP -> 0.04%
@150 oC for 0.5 h, 0.08% @ 200 oC for 2 h- Al-FPC production requires various thermal cycles:
- Outgassing: 180 oC - Al sputtering : 90-130 oC- Image transfer: 80 oC- Solder mask: 180 oC
- Metrology check to measure induced “shrinking”: distance between first and last contact along trace lines (nominal 268.8)
11/03/2014
ITS-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)
11/03/2014
sample stage results
DEPHIS before solder mask
5 lines of same FPC: 268.562, 268.575, 268.545, 268.565, 268.528AVG= 268.56, STDEV=0.019
FHR before etching
5 lines of same FPC: 268.405, 268.396, 268.379, 268.366, 268.384AVG= 268.39, STDEV=0.015
DEPHIS before Ni/Au
2 lines of 5 different FPCs:- 268.387 268.357 - 268.238 268.279- 268.345 268.368- 268.228 268.246- 268.300 268.318AVG 268.3 268.32STDEV 0.07 0.052
ITS-MFT mini-week - Al-FPC - A. Di Mauro 18
Eye diagram
11/03/2014
• FPC in Cu, 50 mm polyimide ~ 90 W impedance (similar to Al FPC with 75 mm polyimide)
• 1.5 Gbit/s
(by M. Keil and A. Junique)
ITS-MFT mini-week - Al-FPC - A. Di Mauro 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
11/03/2014