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Electronics => Manufacturing & Assembly => Topic started by: e100 on June 26, 2022, 02:44:53 am

Title: "Arc lighters" and surface treating plastics for better adhesion?
Post by: e100 on June 26, 2022, 02:44:53 am
Has anyone used one of those electric lighters gadgets for surface treating hard to glue plastics such as PVC?
I don't want to burn the plastic, just change its surface chemistry.

https://youtu.be/voTVI0bL9C4?t=153 (https://youtu.be/voTVI0bL9C4?t=153)

Are these things deadly to electronics?
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: Uunoctium on June 26, 2022, 03:28:43 am
due to lack of purge gas flow this is not an cold plasma what's normally used for etching!
With such an arc lighter you will immediate burn plastics -  too hot

but you can modify it :)
https://siamagazin.com/a-cold-fire-torch-that-you-can-touch-and-not-get-burned-explained/
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: e100 on June 26, 2022, 04:37:34 am
due to lack of purge gas flow this is not an cold plasma what's normally used for etching!
With such an arc lighter you will immediate burn plastics -  too hot

but you can modify it :)
https://siamagazin.com/a-cold-fire-torch-that-you-can-touch-and-not-get-burned-explained/

Looks complicated to build and needs an argon or helium supply.

Would a normal stream of air going through the discharge of an arc lighter still allow the arc to form but keep it cool?
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: Marco on June 26, 2022, 06:57:50 am
I'd be scared of that electrode arcing to my finger in that demonstration in the video, the plasma might not burn it but a HF arc can be nasty.
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: twospoons on June 27, 2022, 05:03:03 am
Looks complicated to build
Its not really. Simple 2 transistor push/pull oscillator built around a tv flyback to give ~20kV @~20kHz.
and needs an argon or helium supply.
Air works just fine. Probably even better for surface treating plastics - all those oxygen radicals do a great cleaning job.

Ideally you want to set this up for dielectric barrier discharge.

Years ago I built a low pressure version for treating LCP, and the increase in glue bond strength was incredible. LCP is one of those difficult plastics.
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: e100 on June 27, 2022, 06:34:58 am
How about an ozone generator. Is this the same principle with electrodes separated by a dielectric?

https://youtu.be/yfmWGl1DRWI?t=195
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: jpanhalt on June 27, 2022, 09:48:18 am
One can and I have used simple flame treatment with a propane torch.  That's an old technique.  There are lots of articles on it.  Here's one of the first to  pop up on my search: https://www.sciencedirect.com/topics/engineering/flame-treatment (https://www.sciencedirect.com/topics/engineering/flame-treatment)

For Teflon, I use a chemical etchant.
Title: Re: "Arc lighters" and surface treating plastics for better adhesion?
Post by: Marco on June 30, 2022, 08:57:09 pm
Is this the same principle with electrodes separated by a dielectric?

Same principle, but ozone accumulates across that tube and plasma is already gone by the time it gets to the output. A cold plasma torch has to generate the plasma very close to the exit.