Author Topic: Any info on this thermal pad for the controller/heatsink?  (Read 2034 times)

sunchaser

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Any info on this thermal pad for the controller/heatsink?
« on: April 12, 2021, 03:37:27 PM »
Hello everyone.  I'm trying to find a replacement thermal pad for my Enertia Basic.  The pad goes between the controller and heatsink. 

Unfortunately I don't have any information on the existing pad.  The dimensions are roughly 173mm x 225mm which is quite large from what I've seen online.  Also, most of the thermal pads seem to be made of some kind of silicon material, and the existing one is more like a metallic foil.

If anyone can share some information on the specifics of this thermal pad I would appreciate it. 

Thanks.

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #1 on: April 12, 2021, 03:41:55 PM »
Just confirmed that the existing thermal pad is electrically conductive.

KaFr

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sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #3 on: April 13, 2021, 08:39:43 AM »
Thank you for the link.  From what I can tell, the thermal pads that they offer are silicone based.  I'm hoping to find something closer to the original material which may be graphite but I'm not sure.  I've done a little research on thermal pads and it looks like the silicone pads have lower thermal conductivity than some of the other materials.

The other challenge is finding a thermal pad that is large enough.  Most of them seem to be sized for computer processors etc.

I wish there was a Brammo Enertia Basic parts list that mentioned the specifics of the thermal pad.  Oh well.

cybergodzilla

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #4 on: April 13, 2021, 10:36:22 AM »
I had to buy some of the THERM-A-GAP HCS10 Thermally Conductive Gap Filler Pads at work.

We had to buy a minimum at $500.00. It included 11 sheets (Likely 9" x 9") that they cut into small rectangles, 44pcs/ea, at a size we needed. Stuff is like silly putty.

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sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #5 on: April 13, 2021, 11:24:29 AM »
Thank you for the information.  I'm having a hard time finding anything that's large enough. 

I reached out to Digital Motor Control in Germany and they said that the thermal pad wasn't mandatory, but I'm assuming the the controller would last longer with a thermal pad.

KaFr

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #6 on: April 13, 2021, 01:47:16 PM »
I think that if you don't get the large thermally conductive pad you need, you can safely use more smaller pads and stick them on the heatsink right next to each other.
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sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #7 on: April 13, 2021, 01:56:13 PM »
That's a possibility.  Right now I'm trying to find out the maximum temperature that the controller itself can reach so that I can find an appropriate thermal pad.  So far I've only been able to find this info from the Sigmadrive Quick Reference Manual:

the Operating Temperature: -30oC to +40oC ambient around controller.

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #8 on: April 15, 2021, 10:12:42 AM »
Still searching for a suitable thermal pad.  One of the engineers I contacted suggested using thermal paste rather than a pad, but personally I feel that it would be difficult to apply any kind of paste evenly on such a large surface.  The heat sink is 172mm x 225mm.  I also placed a straight edge across the mating surface of the heat sink and discovered that it isn't perfectly flat, but it's pretty close.

At this point I'm leaning towards running the bike without a thermal pad and monitoring the controller/heatsink temperature with an infrared thermometer to see how hot it gets.  The engineer I contacted at Digital Motor Control in Germany said that it wasn't mandatory to use a thermal pad with the heat sink. 

If I decide to replace the thermal pad, I'll probably use some kind of graphite sheet.  The graphite material seems to have the highest thermal conductivity for the money. 

If anyone on the forum has experience with heat dissipation I would very much like to hear your thoughts on this.

Thanks.

« Last Edit: April 15, 2021, 12:28:13 PM by sunchaser »

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #9 on: May 04, 2021, 02:59:58 PM »
After a fair amount of research and educated guesses I've determined that the factory thermal pad is made of graphite.  I ended up ordering the following part from Digikey.com:

MFG: t-Global Technology T62-1-310-310-0.16 

It's a 310mm x 310mm graphite sheet that is 0.16mm thick.  There is adhesive on one side.  It has a thermal conductance value of 15W/m-K.  The price per sheet was about $18 U.S. plus shipping.

https://www.digikey.com/en/products/detail/t-global-technology/T62-1-310-310-0-16-0/3042243

I also considered using this product from the same manufacturer:

T62-310-310-0.13.  It is also 310mm x 310mm.  Thickness is 0.13mm.  Price is about $15 U.S. plus shipping.

It is slightly thinner and without the adhesive backing, but has a higher thermal conductance value of 20W/m-K.  Please note that the factory thermal pad did not have an adhesive backing.  I'd also like to mention that the factory thermal pad was about 0.22mm thick from what I remember.

Here's the Digikey link for this pad:

https://www.digikey.com/en/products/detail/t-global-technology/T62-310-310-0-13/3042241

See the attachment file below for the datasheet on this line of products:

« Last Edit: May 04, 2021, 03:56:29 PM by sunchaser »

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #10 on: May 04, 2021, 03:35:32 PM »
Not only was the graphite pad the same material as the factory pad, but it also had the best performance for the money. 

If you're planning on replacing the thermal pad on your controller, please keep in mind that graphite is a pretty fragile material.  It is easily bent and creased.  Before I did any cutting of the new material, I did some test cutting/hole punches with the old pad to get a feel for the graphite. 

I placed the heatsink on one of the corners of the new pad and used a utility knife to cut the two sides while pressing down on the heatsink so that it wouldn't move.  I maintained pressure on the heatsink and traced the four mounting holes of the heatsink onto the graphite sheet with a pencil.  Once that was done I lifted the heatsink from the graphite sheet and used a hollow punch to make the four holes.  I used hole punch that was slightly larger than the heatsink mounting hole to allow for my holes not aligning perfectly.  I'm glad that I did.  I ended up needing that buffer. 

I was originally planning on using a hammer to strike the punch on the graphite sheet but found that pressing down on the punch with my hand worked just as well.  Make sure that you place the graphite sheet on a firm surface before using the punch.  Once again, it's a good idea to practice on the old thermal pad to get an idea of what works best. 

Using the graphite sheet with the adhesive backing was good and bad.  I liked the fact that it stayed in place once it was applied, but it was really difficult to remove the wax paper from the graphite without bending or creasing the material.  I also had to be careful not to leave any bubbles/air pockets between the heatsink and pad.  Using the graphite without the adhesive might be a better way to go.

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #11 on: May 04, 2021, 03:37:14 PM »
Photos.

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #12 on: May 04, 2021, 03:39:34 PM »
Photos.

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #13 on: May 04, 2021, 03:40:02 PM »
Better to practice with the hole punch on the old pad first.  Second photo is the finished product.  So glad that I made the holes slightly larger.  You might be able to use an X-acto knife for the holes also.
« Last Edit: May 04, 2021, 03:59:28 PM by sunchaser »

sunchaser

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Re: Any info on this thermal pad for the controller/heatsink?
« Reply #14 on: May 04, 2021, 03:41:57 PM »
Once I got the graphite pad mounted to the heatsink I reassembled the heatsink and controller and mounted them back on the bike.  The next step was to replace the PVC pipe wrap tape that goes around the edge of the controller.  The tape is available at your local hardware store or online.  I'm assuming that this is used to prevent water and dirt from getting on the electrical connections on top of the controller.  Note how the two long side pieces are placed first, and then the piece on the top is placed last.  The top piece overlaps the sides as shown in the photo. 
« Last Edit: May 04, 2021, 03:55:17 PM by sunchaser »