Utilization of Stern-Gerlach Effect to achieve direct write deposition of Cu films
Cu 2 O deposition Process
description
Transcript of Cu 2 O deposition Process
Cu2O deposition Process
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Summary
• Concept presentation
• Technical requirements
• Process description
• Advantages
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This new technology relies on the existence of cuprous oxide (Cu2O) in the substrate, which allows the metallization of the surface.
The particles of Cu2O are distributed in the resin which constitutes the substrate to be metallized at the rate of 2,5 to 10 % in volume.
Its transformation into pure metal, Cu°, only operates at the surface and in the micro-holes, when exposed to the contact of a specific chemical reducing agent, a borohydride, following the global reaction :
This reduction converts a discrete distribution of Cu2O particles into a continuous metallic copper layer which can be reinforced by both electroless and electrolytic processes up to the required thickness.
Plating process : Concept presentation
4 Cu2O + BH4- 8 Cu° + B(OH)3 + OH -
K+ BH4-
Cu2O particle
Resin
Cu metal layer
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Plating process : Concept presentation
Products and operation for the process application :
Cu2O particles : pulverulent powder, can be refined, dispersed within the polymeric matrix, cheap and usual product, several suppliers.
Chemical treatment before the reduction to remove the superficial layer of the matrix : to achieve high level of peel strength (see photo 1 next page), to metallize simultaneously holes and surfaces (see photo 2 next page).
Reducing agent : mainly potassium or sodium borohydride usual (several suppliers) and low cost (much cheaper than palladium), easy to handle (not hazardous, in an aqueous form), easy to use : at first sight, borohydride solution can be substituted to palladium batch in the
standard process line.
Optimization to fit the wanted requirement: concentration, size and dispersion of Cu2O particles, chemical treatment before reducing, reduction’s parameters.
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Plating process : Concept presentation
Photo 1 : Interface between the substrate and the copper obtained after a chemical treatment
Photo 2 : Very good peel strength continuity for the metal layer in surface
and holes thanks to reduced Cu2O particles
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PCB prototype that has been obtained through the Cu2O Plating Process Size of the conductor line : 10 µm.
Plating process : Concept presentation
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The Cu2O plating process is protected by 6 patents covering both laser and photovia drilling
Internal patent number International patent number Abstract
R 3043
14.12.81
France, USA, OEB (DE, BE, GB, IT, NL, SE, IR), Japan. Organic substrate metallization process using small filler particles of dispersed non conductive oxide
R 3175
15.04.83
France, USA, OEB (DE, AT, BE, SP, FR, IR, IT, LU, NL, GB, SE, CH), Canada, Korea, Japan, Taiwan, Israel, South Africa, Australia.
Metallization process of thermostable films by reducing copper oxide with borohydride followed by electrolytical deposition
Plating process : Concept presentation
R 3176
15.04.83
OEB (DE, AT, BE, SP, FR, IR, IT, LU, NL, GB, SE, CH)
Canada, USA, Korea, Japan, Taiwan
Israel, South Africa, Australia.
Electrically insulated polymeric film metallization by reducing metal oxide particles with borohydride followed by electrolytical deposition
R 3193
27.05.83
France, USA, OEB (DE, AT, BE, FR, GB, IT, LU, NL, SE, CH), Spain, Canada, Taiwan, Korea, Japan.
Possibility of using both isotropic metallizable polymeric substrates with low CTE and resin including metal oxide particles
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The Cu2O plating process has been developed in the eighties by Rhône Poulenc and suspended for strategic reasons in the nineties.
Plating process : Concept presentation
Internal patent number International patent number Abstract
R 000 99
27.07.2000
French patent deposit before international extension Compatibility of laser drilling with metallization process using reduced copper oxide with borohydride followed by electrolytical deposition
R 00181
29. 12. 2000
French patent deposit before international extension Compatibility of photovia drilling with metallization process using reduced copper oxide with borohydride followed by electrolytical deposition
2001
Patents in progress
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• Concept presentation
• Technical requirements
• Process description
• Advantages
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Three requirements have been tested so far highlighting the potential of the Cu2O metallization process.
Plating process : Technical requirements
Laser drilling possibility
Peel strength potentially exceeding market
requirements
Dielectric constant features fitting market requirements
Technical compatibility
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Cu2O particles do not hinder the laser drilling quality.
Non optimized laser drilling tests for Epoxy + Cu2O
Source: Delta Electronic services
Cu2O weight concentration: 60 %in volume: 10 %
Plating process : Technical requirements
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Dielectric properties are slightly modified by the Cu2O particles and even improved in certain cases
Note: (1) In weight percentage
Properties
Superficial resistivity (/ )
Volume resistivity (/cm)
Dielectric constant Dk (1 MHz)
Dissipation factor Df (1 MHz)
3.1013
5.1014
4,9
0,019
Epoxy
3,6.1013
3,8.1015
4,8
0,018
Cu2O 22% (1)
Measures on ~ 1,6mm laminates
Plating process : Technical requirements
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When initial chemical surface treatments are done, peel strength potentially exceed market expectations.
Treatment types
Treatment 1:• Permanganate or bichromate chemical treatment.• At the end of the treatment, necessity to eliminate chromium
or manganese oxides thanks to hydroxylamine chlorohydrate or sulphate.
Treatment 2:• Alkaline chemical treatment in hydroalcoolic environment.• Potash: 350g; methanol/ethanol/water: 400cm3/50cm3/10cm3
• Temperature: 80°C.
Peel strength fluctuating according to parameters (epoxy type, particle size and dispersion(3) , physicals conditions,…).
Surface peel strength(1) for Cu2O + epoxykg/cm
Notes: (1) Tests realized ten years ago(2) 1,4 kg/cm = 8 lb/inch(3) Concentration between 10% to 50% in weight percentage
Sources: Kermel, Rhône Poulenc
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
2,2
2,4
2,6
2,8
Treatment1
Treatment2
Norm(2)
Plating process : Technical requirements
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With regard to peel strength, Cu2O plating process offers several potential advantages
Kermel's plating process using Cu2O particles
reduced with borohydride
Potential advantages
Very good peel strength continuity in surface and holes thanks to Cu (reduced Cu2O)
Increased peel strength compared to standard epoxy thanks to Cu2O particles anchored
inside the resin
Peel strength level modularity through control of concentration and dispersion of Cu2O
particles
Recycling possibility in case of non satisfactory level of metallization
Plating process : Technical requirements
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• Concept presentation
• Technical requirements
• Process description
• Advantages
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Plating process : Description
At first sight, in the SBU layer production process, minor changes should occur in
major PCB makers production lines to implement the Cu2O metallization concept.
Changes occur principally in 2 steps :
- drilling when compared to RCC (see step 4 of the process chart),
- electroless plating with a substitution of the palladium by the borohydride
reduction bath (see step 5).
With the Cu2O metallization concept, the number of the process steps is :
- 25% less than RCC technology,
- the same than liquid technology.
SBU layer simplified production steps with CO2 laser drilling and with different
elaborated materials is presented in the 4 next slides.
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Plating process : Description
• Stoving• Stacking• Pressing, heating• Disassembling/cleaning
• Coating• Drying/heating
• Coating• Drying/heating
Copper clad
Cu2Oparticles
• Half etching• Rinsing
Core preparation
Build-up deposition (coating/lamination)
Surface treatment
• Stoving• Stacking• Pressing, heating• Disassembling/cleaning
Copper line
Dielectric
Upper core layer
RCC(1) Epoxy/polyimide + Cu2O Liquid resinProduction steps
Dry filmSolids Liquids
• Micro-etching• Rinsing• Black oxydation
• Surface treatment• Rinsing
• Surface treatment• Rinsing
• Surface treatment• Rinsing
SBU layer simplified production steps with CO2 laser drilling and with different elaborated materials
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Plating process : Description
• Etching• Rinsing• Photoresist stripping• Copper oxydation• Rinsing
Drilling
• Surface preparation• Photoresist deposit• Insulation • Development• Rinsing
Photoresist"window"
• CO2 drilling• Etch back• Rinsing
• CO2 drilling• Etch back• Rinsing
• CO2 drilling• Etch back• Rinsing
"Laser" resin
• CO2 drilling• Etch back• Rinsing
"Laser" resin
RCC(1) Epoxy/polyimide + Cu2O Liquid resinProduction steps
Dry filmSolids Liquids
SBU layer simplified production steps with CO2 laser drilling and with different elaborated materials
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Plating process : Description
Note: (1) Process with window creation
Switch the palladium deposit bath by a borohydride reduction bath
• Degreasing• Rinsing• Pre-catalysis• Catalysis• Activation
• Degreasing• Rinsing• Pre-catalysis• Catalysis• Activation
• Thin chemical copper deposit • Rinsing
• Fastened thick chemical copper deposit
• Rinsing
• Thin chemical copper deposit • Rinsing
Electroless plating
Image transfer
Chemicalplating
Palladium
Photoresist
• Surface preparation• Photoresist deposit• Insulation • Development• Rinsing
• Degreasing• Rinsing• Pre-catalysis• Catalysis• Activation
• Thin chemical copper deposit • Rinsing
• Surface preparation• Photoresist deposit• Insulation • Development• Rinsing
Photoresist
RCC(1) Epoxy/polyimide + Cu2O Liquid resinProduction steps
Dry filmSolids Liquids
• Surface reduction with potassium borohydride
• Rinsing
Copper
• Fastened thick chemical copper deposit
• Rinsing
Epoxy/polyimide + Cu2O
• Surface reduction with potassium borohydride
• Rinsing
Copper
SBU layer simplified production steps with CO2 laser drilling and with different elaborated materials
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Plating process : Description
Note: (1) Process with window creation
SBU layer simplified production steps with CO2 laser drilling and with different elaborated materials
• Etching• Rinsing
• Differential etching• Rinsing
• Differential etching• Rinsing
• Differential etching• Rinsing
Electrolytical plating
Etching
• Copper deposit• Rinsing• Photoresist stripping• Rinsing
• Copper deposit• Rinsing• Photoresist stripping• Rinsing
RCC(1) Epoxy/polyimide + Cu2O Liquid resinProduction steps
Dry filmSolids Liquids
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• Concept presentation
• Technical requirements
• Process description
• Advantages
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Plating process : Advantages
This new plating process is :Easy to implement
- Process gets simultaneously plated holes and surfaces.- Products are usually cost competitive and easy to handle (Cu2O and borohydride).- Number of process steps reduced.- Compatibility with liquid/film technologies.
Reliable- Due to the high level of peel strength achieved.- Peel strength of plated copper increased in surface and in micro-via holes.
Technologically advanced- Reliable access to additive/semi additive processes.- Reliable access to fine line.- The presence of Cu2O particles, compatible with the dielectric and CTE requirements, enhance the thermal transfer of dielectric matrix.
Economic- Reliability and more specifically of plated micro-holes.- Saving of labor because of less steps and operations.- Saving of investment because minimum changes in production lines for PCB makers.
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As a conclusion, the Cu2O Plating Process is easy to implement, technologically advanced, and above all, reliable and economic.
In that way, our innovative plating technology : • comes up to current specifications and even exceeds the market
expectations,• answer potentially to the evolution in specifications,• is adaptable to most industrial processes.
For more information, please contact :
V. LORENTZMarketing Department
Tel : + 33 (0)3 89 20 47 44Fax : + 33 (0)3 89 20 47 38
www.kermel.com
Plating process : Conclusion