Here's a cool heat sinking subtopic...screwing down versus clipping the chip to the heatsink. There would seem to be a lotta pluses to clipping.
Pros of Clipping TO220s:
1- Even clamping pressure over a greater surface area of the chip
2- No doubleguessing about how tight to screw things
3- No additional concerns over the screw making contact with the metal and shorting the chip
4- No screw and nut to figure out
5- No holes to drill into a nice virginal heatsink
6- Quick and easy...easy to undo
Cons of Clipping TO220s:
1- Maybe...not enough pressure to make good thermal contact?
2- Maybe...clip may come off under jarring or shock to amp chassis?
3- ...
I'm grasping for cons here...
In particular, I'm talking about Aavid Thermalloy's very Max Clip system
http://www.aavidthermalloy.com/products/maxclip/index.shtml
I'm seriously considering using these "Clip Over Edge" clips with my Wakefield 401-K heatsink...call me lazy
http://www.aavidthermalloy.com/cgi-bin/mxclipsrch_all.pl?Package=edge&Search1=Search
Pros of Clipping TO220s:
1- Even clamping pressure over a greater surface area of the chip
2- No doubleguessing about how tight to screw things
3- No additional concerns over the screw making contact with the metal and shorting the chip
4- No screw and nut to figure out
5- No holes to drill into a nice virginal heatsink
6- Quick and easy...easy to undo
Cons of Clipping TO220s:
1- Maybe...not enough pressure to make good thermal contact?
2- Maybe...clip may come off under jarring or shock to amp chassis?
3- ...
I'm grasping for cons here...
In particular, I'm talking about Aavid Thermalloy's very Max Clip system
http://www.aavidthermalloy.com/products/maxclip/index.shtml
I'm seriously considering using these "Clip Over Edge" clips with my Wakefield 401-K heatsink...call me lazy
http://www.aavidthermalloy.com/cgi-bin/mxclipsrch_all.pl?Package=edge&Search1=Search
The only minor thing I can think of is the messy way to mount it with paste or silicon patch, never found the right tool to keep the spring open.. The system in the slideshow-picture in your first link looks interesting in that perspective...
Here's what I once did to attach a slab of aluminum to a T-amp chip:
Here's what I once did to attach a slab of aluminum to a T-amp chip:
Attachments
Nice...but is that clip for retaining or cooling?
I don't think that clipping changes the grease mess much other than there's no reason to grease either side of the "clipover the edge" clip...it's not really intended to add any cooling in my application although it prolly does by a nominal amount.
I don't think that clipping changes the grease mess much other than there's no reason to grease either side of the "clipover the edge" clip...it's not really intended to add any cooling in my application although it prolly does by a nominal amount.
Somewhere, sometime, I saw a clip that screwed at one end into the heatsink, supporting the chip by the other end.
I know this almost defeats the purpose of "clipping" that you're talking about, but it does allow the chip to be mounted on a chunky heatsink, and it will hold the chip more evenly on the sink than simply a screw at one end.
I've been trying to find something similar for my LM amp chips, but haven't managed yet... Let me know if you do!
I know this almost defeats the purpose of "clipping" that you're talking about, but it does allow the chip to be mounted on a chunky heatsink, and it will hold the chip more evenly on the sink than simply a screw at one end.
I've been trying to find something similar for my LM amp chips, but haven't managed yet... Let me know if you do!
In the Genelec monitors I opened the LM3886s are pressed against the heatsink with a spring clips. Mind you the heatsink in this case is the entire speaker box which is cast aluminium. There is not much air flow inside those boxes (only from the port) but they don't seem to have any problem with heat.
I sorta eyed it up and the heatsink I'm using is .190" thick where the LM3875 would clip/screw to. The other factor that motivated me is that the 401-A version of this heatsink with a hole for the TO220 is $12something while the non-holy 401-K version is $8something. $4 a hole? That's too much $$$. So you see...both laziness and cheapness combined to have me look at the Max Clips
As I pound the email/internet/phones to source these clips, I'm finding out that Aavid plays the proprietary game with the Max Clips and they're unobtanium. I'm trying to get some free samples but basically they want you to buy their extrusion.
However, for you folks near Bavaria, I found two vendors that had a very cool selection (better than Aavid) for clips.
Kunze (look for Powerclips)
http://www.heatmanagement.com/kunze/00english/
Fischer Elektronik
http://www.fischerelektronik.de/index.php?id=114&L=1
Of course, the distribution in North America is crap
Anyone close to these vendors willing to source some clips?
Danke schon!
However, for you folks near Bavaria, I found two vendors that had a very cool selection (better than Aavid) for clips.
Kunze (look for Powerclips)
http://www.heatmanagement.com/kunze/00english/
Fischer Elektronik
http://www.fischerelektronik.de/index.php?id=114&L=1
Of course, the distribution in North America is crap
Anyone close to these vendors willing to source some clips?
Danke schon!
Clip Alternatives
In the spirit of DIY'ing, and to hopefully spur creativity, here is a technique I've seen for clipping down power transistors.
Try using regular old, store-bought (Office Depot or virtually any place that sells office supplies) heavy-duty paper clips. The medium ones measure about 1.25" wide, 0.75" tall, and will open up to 0.5". The large ones measure about 2" wide by 1.33" tall and will open up to about 1". Sounds crazy, I know, but they are commonly available, made of good quality spring-steel that retains its properties at 85 degrees C, includes the wire clips for installation/removal (which can be removed by pinching them), and are very cheap.
The medium one can easily retain 2 x TO-220 or TO-218 devices, or 1 x chip amp. It can also hold those devices against aluminum up to 3/8" thick. I haven't used the large ones, but imagine they can hold multiple power devices or a couple chip amps against (up to) 3/4" aluminum.
I have used this mounting method for a prototype car amp with flawless results. The pressure is constant and so long as the aluminum is the correct height and thickness, mounting takes seconds. I first saw this method used on a motor controller that used 4 x "paper clips" to hold 8 x power FETs. At first I thought it was silly and ineffective, but quickly realized it was extremely practical and very effective.
These clips can be used with very large heatsinks as long as large "L" or even "U" shaped aluminum channel with the channel thermally secured to to the heatsink.
Anyway, hope this helps or provides some alternative ideas.
In the spirit of DIY'ing, and to hopefully spur creativity, here is a technique I've seen for clipping down power transistors.
Try using regular old, store-bought (Office Depot or virtually any place that sells office supplies) heavy-duty paper clips. The medium ones measure about 1.25" wide, 0.75" tall, and will open up to 0.5". The large ones measure about 2" wide by 1.33" tall and will open up to about 1". Sounds crazy, I know, but they are commonly available, made of good quality spring-steel that retains its properties at 85 degrees C, includes the wire clips for installation/removal (which can be removed by pinching them), and are very cheap.
The medium one can easily retain 2 x TO-220 or TO-218 devices, or 1 x chip amp. It can also hold those devices against aluminum up to 3/8" thick. I haven't used the large ones, but imagine they can hold multiple power devices or a couple chip amps against (up to) 3/4" aluminum.
I have used this mounting method for a prototype car amp with flawless results. The pressure is constant and so long as the aluminum is the correct height and thickness, mounting takes seconds. I first saw this method used on a motor controller that used 4 x "paper clips" to hold 8 x power FETs. At first I thought it was silly and ineffective, but quickly realized it was extremely practical and very effective.
These clips can be used with very large heatsinks as long as large "L" or even "U" shaped aluminum channel with the channel thermally secured to to the heatsink.
Anyway, hope this helps or provides some alternative ideas.
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