VIII] Packaging and Housing concepts

Question 1

What are the two mains objectives surrounding packaging and housing ?

Answer 1

Protecting the body from the device and protecting the device from the body.

Question 2

What are the basic components for stiff active implants in conventional technology ?

Answer 2

Titanium - Ceramics - Glass

Question 3

What are the basic components for FLEXIBLE encapsulation in active implants in conventional technology ?

Answer 3

Parylene C,
Silicone Rubber
Polyimide

AROUND THE DEVICE.

Question 4

Which material for IC housing ?

Answer 4

DLC (diamond like carbon), hermetic (metal) or silicon/nanocrystalline carbon

Question 5

Which properties are desired for meterials of housing, packaging and encapsulation ?

Answer 5

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.

Question 6

Site the functional components and groups in active implants

Answer 6

Sensor/actuators
Cable
Plugs 
Implant housing with electronics
Extracorporal application device

Question 7

According to what the material selection and design have to be done.

Answer 7

Anatomy
Mechanical load
Energy load

Question 8

Site materials from the less to the more permeable.

Answer 8

Gases, silicones, epoxies, fluoro carbons, glasses, ceramics and metals.

Question 9

Define the hermeticity

Answer 9

Definition of leakage rate over time(>10 power 9 mbar l/s)

Question 10

What is the arrhenius function ? What is it used for ?

Answer 10

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°.

Question 11

Describe the use of titanium as material for implant concepts

Answer 11

It is a robust and biostable material
Titanium oxide can serve as stable passivation layer
External coil for energy and data transmission

Question 12

What does it mean “titanium oxide as stable passivation layer”

Answer 12

less readily affected or corroded by the environment

Question 13

Describe the use of ALUMINIUM as material for implant concepts

Answer 13

AL2O3
Ceramic-Metal connection
Welding of metal ring closes package
Transmission coil can be placed inside.

Question 14

Describe the use of METAL GLASS feedthroughs as material for implant concepts

Answer 14

Metal brazing and glass melting.
Matched or compression seal(=sceau)
Oxide or oxide free bonding mechanisms
The glass is directly bound to metal.

Question 15

In metal glass feedthroughs, what kinds of metal are used?

Answer 15

KOVAR (FeCoNi alloy)
Steel
Fe-Ni alloys

Question 16

In metal glass feedthroughs, what kinds of glass are used?

Answer 16

Borosilicate or Barium alcaline

Question 17

What are Metal-ceramic feedthroughs ?

Answer 17

A Brazing of glass and ceramics, in this type of FTs adhesion promoter on ceramc substrate is necessary.

Question 18

What are the type of plugs for cables and electrodes ?

Answer 18

IS-1 and Craggs connectors.

Question 19

What are IS-1 ?

Answer 19

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.

Question 20

What are Craggs ?

Answer 20

Plugs for cables and electrodes. They consist in a mechanical connection and a crimping of cable (cooper)-plug connection.

Question 21

Why hybrid assembly pf miniaturized implants are made ?

Answer 21

To make MICRO technologies. Combine technics allows smaller product creation.

Question 22

What are pros and cons of hybrid assembly of miniaturized implants.

Answer 22

Low cost but small volume production.

Question 23

What are the components of integral substrate packaging ?

Answer 23

Al2O3 substrate
AU FT
Electronic components
Protective varnish
AlO3 ring
Cu Ring
AuPt metallization
SnPb sulder
Au final seal 
Al2O3lis

Question 24

What is the composition of Gold cap integral substrate packaging ?

Answer 24

PbSnAg final seal, SnAg solder, Au cap, PtAu metallization, AL2O3 substrate , AU pin and Pb Sn Ag fillet.

Question 25

Which materials are used for non hermetic polymer encapsulation ?

Answer 25

Silicone rubber and parylene C

Question 26

What are the two main philosophies for encapsulation ?

Answer 26

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.

Question 27

In which case Parylene C and silicone runer IOL for intraocukar encapsulation has been used ?

Answer 27

For epiretinal vision prothesis.

Question 28

What are the 5 main types of material for MEMS insulation (hermetic

Answer 28

SiO2
Si3N4
Polyimide
Metals
parylene C

Question 29

What kind of degradation can happend in Silicon based layers ?

Answer 29

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

Question 30

What is the treak to increase stability of Si based layer ?

Answer 30

The thicker a material is, the longer it will take to get it knoked so we can create multiple layers

Question 31

Site at least 4 components for bonding technologies

Answer 31

Anodic glass Si
SI SI direct
glass frit
Solder/eutetic
polymer (not ermetic so no)
thermo compression
localized heating
RF/microwave/ultrasonic
laser

Question 32

Site components for Package materials

Answer 32

Glass/ceramic
silicon
Thin films

Question 33

Site components for feedthroughs materials

Answer 33

Lateral (On wafer)
Vertical (Thru Wafer)
Optical/fluidic

Question 34

What are the two main approaches for Vacuum packaging ?

Answer 34

Using Thin films or using packaging with bonding/cappinh which is thicker