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Hardware => Lynx Express => Topic started by: WWNF911 on June 13, 2009,

Title: Heatsink compound
Post by: WWNF911 on June 13, 2009,
Started building my first Express this week and ran into a snag. Poor thing has just been sitting there since last tuesday.
Can anyone possibly make a short video showing how much HS compound to use and how yu apply it? My first HS. Don't want to waste it. RS only had 2 tubes. (wow are they small) at 3 bucks each. I have 6 boards to make and think I'll probably run out. Additionally, It is such a tight fit, how do you apply HS compound to vertical headers and push Volt reg. and other into header without  compressing all the compound out and defeating the purpose and or damaging the part trying to push it in. Anyone have any good suggestions.
Last question,... (I have all V3 PCBs) when installing the HS, it looks like the HS will be close to if not touching all the resistors and making them all same potential. Am I the only one who noticed? Don,t want to short anything out. Anyone have to bend triac legs to make more room? Anyone have any suggestions?
Thanks
Leon
Title: Re: Heatsink compound
Post by: Ron on June 13, 2009,
I can only speak for myself on how I do it and I'm not sure if I have built a V3 board yet.  On the heatsink compound you only need a little dab.  I put just a tiny, tiny bit on the metal portion of the tab that will push up against the heatsink.  I have one tube of heatsink compound and I have used it to build at least 5 LE boards.   It really doesn't take much.  In fact too much and it will squeeze all over and it is messy.

I'll see if I can get to doing a video for you at some point this weekend.

I'm not sure I have installed one of the new heatsinks yet either.  Do they have a standoff little piece of plastic to use to get it to set up off of the board?  That should be enough to keep it away from the resistors.

Ron
Title: Re: Heatsink compound
Post by: vairmoose on June 13, 2009,
That 3 oz tube is enough 9 LE's.  (I still have a drop in my tube after 9).   You only put enough on the surface of the triac to "wet" the triac. and don't worry about covering the whole surface.   Tighten the screw down nice and snug.  The purpose of the compound is to ensure a good mating surface for the heat transfer.  

You can tweak the triacs (bend them) a little but recommend using a soft touch and not too often.  The real problem can be weakening the solder joint.

Hope this helps.

larry

There shoiuld be two small diameter nylon washers in the kit (about 1/4" long) that will space the heatsink above the board. 
Title: Re: Heatsink compound
Post by: WWNF911 on June 13, 2009,
Thanks gentlemen. Ron you were right. I inventoried hardware that came with the heatsink and yes there is a couple of nylon washers and spacers.

Thanks to both of you.

All I need to do now is figure out exactly what a dab is.

It's kinda like learning southern cooking I guess.  (You know,... a smidgin of this a dash of that etc.)
Title: Re: Heatsink compound
Post by: WWNF911 on June 13, 2009,
Here's the side view.

Need one of these in the wiki.  :)

Couldn't hurt to also have video of applying the "dab" as well.   

Leon
Title: Re: Heatsink compound
Post by: Greg on June 13, 2009,
You want to use a very small amount of compound.  If you're using those little radio shack tubes, just squeeze enough to get a bit out the end of the tube and use the tube end to spread it very thinly (thin enough its translucent) on the back of the triac's metal tab.

Literally, if any squeezes out when you press the triac down on the heatsink, you've used too much.  Most of the heat transfer takes place right under the mounting screw which is where the best contact will be with the heatsink. 

Larry's right, you should be able to complete at least 9 LEs with one of those tubes.

Greg
Title: Re: Heatsink compound
Post by: WWNF911 on June 14, 2009,
Thanks to all. I don't know why but I have the urge to think that I probably used less than what I should have but from the sounds of it I did that on purpose because it sounds like I would've used too much.   (If that makes sense)


BTW,... Rick my last post had a pic of the side view showing the spacers for the heatsink install. I'm embarrassed to say your explaination in the manual was more than adequate. I suppose the picture would come in handy for those who might say a picture is worth a thousand words but you did a great job. I just caint read I guess.   :-[

Thanks again all.

I'm off to find the appropriate tool to make my dremel into an etcher. Why you ask? Hmmm.....
Title: Re: Heatsink compound
Post by: Sloanhaus on June 14, 2009,
Do you have to use heatsink compound on the heat sinks, and do you have to use the spacers, it doesnt touch the board?
Title: Re: Heatsink compound
Post by: RJ on June 14, 2009,
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Do you have to use heatsink compound on the heat sinks, and do you have to use the spacers, it doesnt touch the board?


Yes you do need to use the spacers and I doubt that there is anyone not doing it. Well maybe?
Compound should be put on so if you decide to run rated power or even close.

RJ
Title: Re: Heatsink compound
Post by: Brad on June 15, 2009,
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Thanks gentlemen. Ron you were right. I inventoried hardware that came with the heatsink ans yes there is a couple of mylon washers and spacers.

Thanks to both of you.

All I need to do now is figure out exactly what a dab is.

It's kinda like learning southern cooking I guess.  (You know,... a smidgin of this a dash of that etc.)

Leon,

I "dab" is a little less than a dollop.
Seriously...this  :D smiley occupies enough space for compound for about 4-5  triacs, not piled very high.
I'm sure it's clear as mud now....

Brad
Title: Re: Heatsink compound
Post by: WWNF911 on June 15, 2009,
Thanks Brad.   LOL

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I'm off to find the appropriate tool to make my dremel into an etcher. Why you ask? Hmmm.....

Success! Well last night anyway. Had to work late again tonight. Time enough left to solder up an SSR4 me thinks.
Title: Re: Heatsink compound
Post by: KeithTarpley on June 16, 2009,
Greetings,,,

Looks like success to me.  Congrats...

Keith
Title: Re: Heatsink compound
Post by: wbuehler on June 16, 2009,
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Thanks Brad.   LOL

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I'm off to find the appropriate tool to make my dremel into an etcher. Why you ask? Hmmm.....

Success! Well last night anyway. Had to work late again tonight. Time enough left to solder up an SSR4 me thinks.

Nice engrave The controller looks good too.

Bill

Title: Re: Heatsink compound
Post by: WWNF911 on June 16, 2009,
Thanks guys.  :)