1. Saclay MPGD workshop

2. Saclay MPGD workshop in 2010 Operation
Bulk description
Saclay MPGD workshop in 2010
Description
Operation
R&D
Prototype realization
Team
Goal (RD, prototypes, series)
First realization
Summary and realization pictures

3. Realization process 1) PCB cleaned (strips, pixels,…)
The bulk process use PCB industry machines. Photoresist film are polymerize on a PCB with the mesh between them . The mesh is then definitely embedded on the redaout board.
1) PCB cleaned (strips, pixels,…)
2) Lamination of the photoresist film (50 to 150 µm)
3) Integration of a mesh on a frame (woven SS mesh 19 µm, 500 LPI)
4) Lamination of the photoresist film (50 µm)
5) UV insulation trough a mask
6) Development UV
7) Curing (UV et four)
2 to 4 mm
50 à 100 mm
Plots: f 200 à 400 µm
Mini: 4 mm
Masque
Photoresist 2
Mesh
Photoresist 1

4. Saclay MPGD workshop Between 2008 and 2010 four machines were bought:
Mesh stretcher
Laminator
UV Insulator
Development unit
The workshop is installed in a clean room (64 m2 of class )
The first 4 month were dedicated to the qualification of the machines (abacus for each machine) on simple test PCBs. Validation detectors were tested under gas with Fe55 for validation.

5. Mesh stretching
The standard bulk are made with a woven SS mesh ( Bopp SDC 45/18).
The goal of the stretching machine is to obtain a mesh glued on a frame with some 8 N/cm tension.
The frames are made on purpose by the mechanical workshop
Tension and gluing of 4 mesh for 20x 20 cm PCB each

6. Laminator
The photoresist film (Pyralux PC) are laminated on the PCB. The maximum width is 600 mm. Two thickness can be used, 50 and 64 µm, with several layer to obtain the amplification gap (typically 128 µm). The mesh stretched on a frame is laminated with (under) the last layer. The 128 µm amplification gap is theoretical : depending of the pressure of lamination this gap varies between 110 and 120 µm.
Oven
laminateur

7. Laminator
Lamination 1st layer
After laminating the last layer

8. UV insulator
The goal of the laminator is to polymerize the layers of photoresist that encapsulate the mesh.
A insulating mask allows to polymerize pillars ,on the active area and , borders and zone for HV contact. The important parameter is the insulation energy (mJ/cm2)
rinsing
Developing unit
insolator
Atelier côté insolateur

9. UV insulator
Insolateur ouvert avec PCB et masque
insolateur

10. Development unit
The developing unit dissolves the photoresist part that were not insulated. The liquid bath is made of water with 1% of carbonate sodium. Several pass are necessary to develop the layer through the mesh with rinsing between each development.
PCB in
development
rinsing

11. PCB rinsing
Between development of the photoresist several rinsing are done to remove the photoresist under the mesh .
rinsing
Develop bulk with mesh frame

12. PCB machining
In 2009 we bought a PCB machine device (originally made to create PCB: 600 x 400 x 120 mm). Goals:
cut of the bulk after realization
Segmentation of the mesh
Realization of small PCB interface card
Machine and PC
Machine clas12 prototype

13. Upgrade of the workshop
The goal of the workshop been R&D the tool will upgrade with new idea arriving.
HV bulk qualification test bench(2011)
The goal is to have a HV cooking test bench with dry air to deliver bulk with few nA at 900 V
New tool with new idea….

14. Goal of the workshop Realization and test in 48 hours !!!
Realization of simplified bulk with innovation (R&D)
Thin Mesh
Segmented mesh
Multi stage mesh
Upgrade of existing techniques (R&T)
Pillar seize
Mesh tension
Double sided bulk
Upgrade of the process in term of quality (R&Q).
Realization process
Data base of component
Feedback after test of bulk

15. Workshop team
The team is composed of 5 persons each at 20% to 50 %. Other personal of experience will come in the lab to participate to the realization. .
Marc ANFREVILLE : coordinator of the activity
Stephan AUNE : Workshop creation, contact person, detector R&D
Julien GIRAUD : management of the quality
Arnaud GIGANON : realize et qualifies bulks for R&D and validation of processes
Robert DURAND : prepare tool and bulk realization
X.X detector CAO
Marc
Stephan
Julien
Arnaud
Robert X

16. Abacus & pillars pictures
PCB 051 – 700mJ – 70° L
D=600
D=700
D=800
26/10/09 au 06/11/09 – AG/RD/MA

17. Bulk done (04/2010 to 12/2011)

18. Double side bulk 72 Channels = 1296 strips!!!
Micromegas Double sided bulk for cosmic bench
Fine spatial resolution: 200 µm pitch
Large active area: 260 x 260 mm
Low amount of electronic channel: 72
The idea is to multiplex the strips and to remove the ambiguity by doubling the detectors (one thin multiplex strips and one large strips)
The DS bulk will be used on cosmic test bench to characterize CLAS12 detectors: 2 scintillators + 4 DS (2 XY).
72 Channels = strips!!!

19. DS Bulk PCB layout
The PCB is a 4 layer with thin strips on top and large strips on bottom. Inner layers for fine strips multiplexing and shielding between active areas.
Thickness 0,8 mm. one 72 unique connector for AFTER readout
Multiplex strips: 36 x 36 = 1296 1 1 1 1 1 1 37 38 39 40 36 36 36 36 36 36
PCB top side
36 x36 strips with a pitch of 200 µm
PCB bottom side
36 strips with a pitch of
36 x 0,2 = 7,2 mm

20. Clas12 double sided bulk for cosmic bench
Event from cosmic test bench
Cosmic on double side bulk
Cosmic on clas12 PYD3 bulk
One large strip hit
4 small strips hit
Clas12 double sided bulk for cosmic bench

21. R&D Macro mesh segmentation Thin flat bulk
To obtain mesh segmentation on thin PCB (200 µm) we go for macro segmentation with dead zone of 5 mm. In 2010 micro segmentation (500 µm) was done with PCB machining device.
First test for macro segmentation are OK. A large CLAS12 detector will be segmented in January 2012
Thin flat bulk
The goal is to have thin bulk glued on honeycomb structure.
First test are OK. An old detector was glued, under HV test.
Large thin bulk to be glued beginning of 2012 (CLAS12 and COMPASS)

22. Tested after removing the photoresist on one side.
Bulk with exotic woven mesh (stainless steel and nylon) for GANIL test (J. PANCIN)
Stainless steel wire
Mesh HV pad
Nylon wire
The mesh HV pad allowed voltage only on several wire out of the active area !!!    
Tested after removing the photoresist on one side.
No positive test for nylon charging issue. To be continued.

23. Bulk with thin mesh
Goal: make a bulk detector with thin electroformed mesh
Several detector were made with 5 µm nickel mesh taken from old compass detector
After two tentative we succeeded in obtaining a bulk with no default. The mesh was not stretched yet at this stage.
Further test with mesh from Euromip (Precision E-forming) under way. Nickel mesh of 5 µm and 10 µm electroformed on frame is under realization.
Test in February 2012

24. Multi layer bulk
In order to make R&D on bulk with large amplification gap we have made tests to polymerize several layer of photoresist.
Up to 8 layers of photoresist were laminated to obtain 500 µm pillars.
Tested By J.Pancin. Result is not yet understood
Same HV limit for 128, 256 and 512 µm gap !!!

25. Pillar R&D
When polymerize through the mesh the pillar under the mesh are equipped with “pods”. This could explain the sparking issue when first HV cooking (up to 900 V in air) Test with double insulation are under way.
Albert retourné avec ses pod en l’air (partie de pod en l’air…)
Albert possède 8 à 9 pods

26. Summary The Saclay MPGD workshop allows us to have plenty R&D underway
Ideas can become reality and tested in some 48 hours
The workshop is open for R&D to IRFU project and collaboration (RD51, Ganil, IN2P3, CENBG, MSU, Riken,…).
Contact person:
Stephan AUNE.

27. Clas12/COMPASS CERN test beam