vias Objective Objective vias EST-DEM Present and - - PowerPoint PPT Presentation
vias Objective Objective vias EST-DEM Present and demonstrate the Chemical Vias production process used on CERN Compare with other process used to produce vias Patented by CERN, to make microvias on high density printed
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Patented by CERN, to make microvias on high density printed multilayer circuits of different type, such as: SBU-Sequential Build-up HDI-High Density Interconnected MCM-L-Multi Chip Modules laminated
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Better relation Price/Integration
After PCB is the must available technology Size decreasing of the electronic components DIL-SMD-BGA-µBGA-SMART CARD Increase in track density and/or a reduction on layer count
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Other handheld products
Microvias are used to electrically connect a layer n with a layer n+1 in a multilayer printed circuit. High density circuits HDI
CERN detector
Portable PCs Video cameras Digital photo cameras
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Types of Vias:
Via holes diameters range from 50 µm to 300 µm. By IPC, PCB’s with vias hole sizes smaller then 6 mils (0.15 mm) are called
microvias.
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Types of Process for the production of µVias:
Our Process
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Photo Image
Cu Photo Imageable Dielectric Develop dielectric Metallization U.V. Exposure
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PLASMA
Cu Cu Dielectric Glue Etching of copper Plasma Etching - Isotropic µ-Attack Metallization ½ to 1 hour for plasma etching Minimal Via diameter ≈ 100 µm
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LASER
Cu Cu Dielectric Glue Laser Cooper Etching Dielectric Laser Ablation Plasma Cleaning Metallization 60 to 80 holes/second For 200 000 holes -> 45 min 1 GEM = 10E6 holes -> 35 hours
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µ Chemical Via
Cu Cu Dielectric Glue Cooper Etching Dielectric Etching Anisotropic Glue Etching Metallization Minimal Via diameter ≈ 40 µm
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µ µ Chemical Chemical Vias Vias
Polyimide Cu A Cu B Resist Resist C U.V. Light U.V. Light D Resist Development E Copper Etch Attack of Polyimide and Resist Strip F Plating G H I U.V. Light U.V. Light J Resist Development Copper etching and resist strip K
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µ µ Chemical Chemical Vias Vias
Laminate adhesive Polyimide coated copper foil L Resist application M N U.V. Light U.V. Light O Resist Development P Copper etch Q Polyimide and Glue etch R Electroplate Copper S Resist application, mask and exposure to U.V.. Resist development and copper etching and strip resist.
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µ µ Chemical Chemical Vias Vias Process Process Process compatible with standard assembly lines for printed circuits
Week initial investment in the standard PCB production lines (15000 EUR instead 600000 EUR Plus maintenance in Laser option) Provide smaller companies to enter in this market Manufacturing cost reduction Maintenance cost are smaller Possibility to have a continuous assembly line
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µ µ Chemical Chemical Vias Vias Process Process Can perform vias of any shape and dimension Global process, all the µvias in the same layer can be done at the same time, in parallel. Time of µvias production don’t depend on the number of µvias to be produced. The more complex the circuit more efficient the process
No possible connection to n+2 layer directly
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Lamination of a metallized sheet of Polyimide on one face with an epoxy glue. Microvia design etch on the copper through a lithographic photo process Etching of the Polyimide by using a sequence of simple chemical baths Elimination of glue by dissolving in the appropriate chemical solution
Steps 1 and 2 are standard
Steps 3 and 4 are the innovative ones
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Pressing Lamination Exposure Development of the resist Etching copper Strip Resist Inspection
Metallization
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Polyimide etching Etching Polyimide Lessive Water
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Glue etching
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Types of Polyimide: Polyimide 1 [5/50/5 µm] Polyimide 2 [5/25/5 µm] Polyimide 3 [5/25/0 µm] Polyimide 4 [2,5/25/2,5 µm] Strips used for measuring the Polyimide thickness.
A A’
Cu Cu Kapton Etching Time ∃ 0’’
Cut AA’
Cu Cu Kapton Etching Time = 0’’
The etching of Polyimide. Bellow there is a micrography of the Polyimide 1 [5/50/5 µm].
ZEISS equipment to measure the thickness of Polyimide.
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Polyimide 1 [5/50/5 µm] Polyimide 2 [5/25/5 µm] Polyimide 3 [5/25/0 µm] Polyimide 4 [2,5/25/2,5 µm]
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Thickness of Polyimide vs Etching time measured with ZEISS
10 20 30 40 50 60 5 10 15 20 Time [min] Thickness [um]
Polyimide 1 used solution Polyimide 1 new solution Polyimide 2 used solution Polyimide 2 new solution Polyimide 4 used solution
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Thickness of Polyimide vs Etching time measured in the cross section
10 20 30 40 50 60 5 10 15 20 Time [min] Thickness [um]
Polyimide 1 used solution Polyimide 1 new solution Polyimide 2 used solution Polyimide 2 new solution Polyimide 4 used solution Polyimide 3 used solution
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Polyimide 1 [5/50/5 µm]
4 min of etching 8 min of etching 12 min of etching 12 min of etching
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Polyimide 3 [5/25/0 µm]
2 min of etching 4 min of etching 4 min of etching
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80 µm 50 µm
Polyimide in the top of FR4. Polyimide thickness is 50 µm
A.R.=1 A.R.=0,625
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