VIII] Packaging and Housing concepts Flashcards
What are the two mains objectives surrounding packaging and housing ?
Protecting the body from the device and protecting the device from the body.
What are the basic components for stiff active implants in conventional technology ?
Titanium - Ceramics - Glass
What are the basic components for FLEXIBLE encapsulation in active implants in conventional technology ?
Parylene C,
Silicone Rubber
Polyimide
AROUND THE DEVICE.
Which material for IC housing ?
DLC (diamond like carbon), hermetic (metal) or silicon/nanocrystalline carbon
Which properties are desired for meterials of housing, packaging and encapsulation ?
Mechanically robost (so it wont break during of after implantation)
Electrical insulator
Barrier against gasses, water and ions (hermeticity)
Permeable for electromagnetic waves (inductive coupling)
Possibly go integrate electrical feedthroughs.
Site the functional components and groups in active implants
Sensor/actuators Cable Plugs Implant housing with electronics Extracorporal application device
According to what the material selection and design have to be done.
Anatomy
Mechanical load
Energy load
Site materials from the less to the more permeable.
Gases, silicones, epoxies, fluoro carbons, glasses, ceramics and metals.
Define the hermeticity
Definition of leakage rate over time(>10 power 9 mbar l/s)
What is the arrhenius function ? What is it used for ?
K = Ae(-E/kT) , the area (A). The larger the temperature is , more energy, fails faster.
It is used to measure the mean time to fail. They measure the MTTF under increased temperature to see the MTTF at 37°.
Describe the use of titanium as material for implant concepts
It is a robust and biostable material
Titanium oxide can serve as stable passivation layer
External coil for energy and data transmission
What does it mean “titanium oxide as stable passivation layer”
less readily affected or corroded by the environment
Describe the use of ALUMINIUM as material for implant concepts
AL2O3
Ceramic-Metal connection
Welding of metal ring closes package
Transmission coil can be placed inside.
Describe the use of METAL GLASS feedthroughs as material for implant concepts
Metal brazing and glass melting.
Matched or compression seal(=sceau)
Oxide or oxide free bonding mechanisms
The glass is directly bound to metal.
In metal glass feedthroughs, what kinds of metal are used?
KOVAR (FeCoNi alloy)
Steel
Fe-Ni alloys
In metal glass feedthroughs, what kinds of glass are used?
Borosilicate or Barium alcaline
What are Metal-ceramic feedthroughs ?
A Brazing of glass and ceramics, in this type of FTs adhesion promoter on ceramc substrate is necessary.
What are the type of plugs for cables and electrodes ?
IS-1 and Craggs connectors.
What are IS-1 ?
They are plugs for electrodes and standard in pacemaker. They can be fixed with a screw and consist in a welding (soudure) of cable-plug interconnection.
What are Craggs ?
Plugs for cables and electrodes. They consist in a mechanical connection and a crimping of cable (cooper)-plug connection.
Why hybrid assembly pf miniaturized implants are made ?
To make MICRO technologies. Combine technics allows smaller product creation.
What are pros and cons of hybrid assembly of miniaturized implants.
Low cost but small volume production.
What are the components of integral substrate packaging ?
Al2O3 substrate AU FT Electronic components Protective varnish AlO3 ring Cu Ring AuPt metallization SnPb sulder Au final seal Al2O3lis
What is the composition of Gold cap integral substrate packaging ?
PbSnAg final seal, SnAg solder, Au cap, PtAu metallization, AL2O3 substrate , AU pin and Pb Sn Ag fillet.
Which materials are used for non hermetic polymer encapsulation ?
Silicone rubber and parylene C
What are the two main philosophies for encapsulation ?
Keep the moisture out with hermetic encapsulation (non polymers) as parylene
Use silicone rubber that can get moisture but you stick things together so it doesn’t matter.
In which case Parylene C and silicone runer IOL for intraocukar encapsulation has been used ?
For epiretinal vision prothesis.
What are the 5 main types of material for MEMS insulation (hermetic
SiO2 Si3N4 Polyimide Metals parylene C
What kind of degradation can happend in Silicon based layers ?
If sodium : Hydrolysis
If Chlorine: Na-Trapping
If electron trapping at surface : Hydrogen diffusion.
Depending on the process technology, degradation and dissolution of Si Nitride and silicon oxide in moisture might occur
What is the treak to increase stability of Si based layer ?
The thicker a material is, the longer it will take to get it knoked so we can create multiple layers
Site at least 4 components for bonding technologies
Anodic glass Si SI SI direct glass frit Solder/eutetic polymer (not ermetic so no) thermo compression localized heating RF/microwave/ultrasonic laser
Site components for Package materials
Glass/ceramic
silicon
Thin films
Site components for feedthroughs materials
Lateral (On wafer)
Vertical (Thru Wafer)
Optical/fluidic
What are the two main approaches for Vacuum packaging ?
Using Thin films or using packaging with bonding/cappinh which is thicker
