Electronic – Help in identifing these 2 materials

capacitorenclosureinsulationmaterialspcb-assembly

i would like to know if anyone of you recognize these 2 materials and what they are used for ?

A material sticky on one side normal on the other , used between capacitors and aluminum enclosure .

A material consisting of 2 parts face is like card board and second part is like thick butter paper. IT is used between 2 pcbs stacked over each other .

Best Answer

I think both materials are there to prevent undesired electrical contact.

Electrolytic caps often have an exposed metallic can container which is electrically connected to one terminal of the capacitor. Having that can touch the aluminum enclosure would be an undesired short to ground.

The two PCBs may have some metallic projections (leads from components on these boards) which could come into contact due to vibration or pressure, so the "butter paper" ensures no inadvertent short can occur.

Related Solutions

Electronic – Have I cooked the caps

See this directly related paper:
Robustness of Surface Mount Aluminum Electrolytic Capacitors When Subjected to Lead Free Reflow

The important and (to me) surprising conclusion is that the case distortion does NOT affect capacitor life. YMMV.

Reflow Sensitivity Results

Time to deformation strongly dependent on capacitor volume
Smallest and largest more susceptible to deformation
Moderate volume capacitors
– 100 – 500 mm3
– More robust
Some capacitors experienced deformation before the 40 second hold time defined in J-STD-020C

Conclusions

Case distortion mainly dependent on the volume of the capacitor

      – Small capacitors under 100 mm3 and   
      - large capacitors over 1000 mm3 susceptible to case distortion
      – Medium capacitors, less susceptible

Case distortion did not influence capacitor life

– No evidence of latency in any sample
Extended temperature or extended lifetime capacitors are more robust

Electronic – What happened when I join two different materials

There is no electric current because there is no potential pushing charges around one way or the other. When you touch two conductors, such as metals, the electrons that can normally hop between atoms of each material can now hop between atoms between the materials. As before, at the macro level no current flows because there is no potential that is pushing the electrons in any particular net direction.

Best Answer

Related Solutions

Electronic – Have I cooked the caps

Electronic – What happened when I join two different materials

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