Filling holes in heatsinks....

B

Brian Soper

Guest
What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.
 
Brian Soper wrote:
What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.
Click to expand...
For all practical purposes, soldering to aluminum is impossible. You would
need a specialty welding rod for aluminum, and practice. LOTS of practice.

--
John Miller
Email address: domain, n4vu.com; username, jsm

Why on earth do people buy old bottles of wine when they can get a fresh one
for a quarter of the price?
 
Heli-Arc process with appropiate grinding and polishing afterwards to
produce a flat transfer surface. Manufacurers use heatsinls with multiple
holes to allow use in multiple applications. Proper applicaton of the themal
transfer medium allows for maximum dissipation even witout considering the
other peforations within the sink itself. If in doubt just change to another
sink configuration or us a bit of aluminim billitt and construct your own. A
bit of machining etc will produce a nice custom item.
"John Miller" <me@privacy.net> wrote in message
news:c853rp$6j8$1@n4vu.com...
Brian Soper wrote:
What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.

For all practical purposes, soldering to aluminum is impossible. You
would
need a specialty welding rod for aluminum, and practice. LOTS of
practice.

--
John Miller
Email address: domain, n4vu.com; username, jsm

Why on earth do people buy old bottles of wine when they can get a fresh
one
for a quarter of the price?
Click to expand...
 
Find a piece of aluminum rod about the size of the hole, peen it over with a
hammer and file it flat.

I assume the hole is round and fairly small.


"Art" <stubby@comcast.net> wrote in message
news:QZWdnQ0BloNmgzvdRVn-gg@comcast.com...
Heli-Arc process with appropiate grinding and polishing afterwards to
produce a flat transfer surface. Manufacurers use heatsinls with multiple
holes to allow use in multiple applications. Proper applicaton of the
themal
transfer medium allows for maximum dissipation even witout considering the
other peforations within the sink itself. If in doubt just change to
another
sink configuration or us a bit of aluminim billitt and construct your own.
A
bit of machining etc will produce a nice custom item.
"John Miller" <me@privacy.net> wrote in message
news:c853rp$6j8$1@n4vu.com...
Brian Soper wrote:
What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.

For all practical purposes, soldering to aluminum is impossible. You
would
need a specialty welding rod for aluminum, and practice. LOTS of
practice.

--
John Miller
Email address: domain, n4vu.com; username, jsm

Why on earth do people buy old bottles of wine when they can get a fresh
one
for a quarter of the price?
Click to expand...
 
no_spam_pls wrote:
Find a piece of aluminum rod about the size of the hole, peen it over with a
hammer and file it flat.

I assume the hole is round and fairly small.
Click to expand...
Assuming the holes are small and not in an unreasonable
configuration, you're likely to lose a LOT more by having
the surface not perfectly flat than you'll gain by filling a hole.
Please publish the before and after thermal resistance numbers
when you're done.
mike



"Art" <stubby@comcast.net> wrote in message
news:QZWdnQ0BloNmgzvdRVn-gg@comcast.com...

Heli-Arc process with appropiate grinding and polishing afterwards to
produce a flat transfer surface. Manufacurers use heatsinls with multiple
holes to allow use in multiple applications. Proper applicaton of the

themal

transfer medium allows for maximum dissipation even witout considering the
other peforations within the sink itself. If in doubt just change to

another

sink configuration or us a bit of aluminim billitt and construct your own.

A

bit of machining etc will produce a nice custom item.
"John Miller" <me@privacy.net> wrote in message
news:c853rp$6j8$1@n4vu.com...

Brian Soper wrote:

What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.

For all practical purposes, soldering to aluminum is impossible. You
would
need a specialty welding rod for aluminum, and practice. LOTS of
practice.

--
John Miller
Email address: domain, n4vu.com; username, jsm

Why on earth do people buy old bottles of wine when they can get a fresh
one
for a quarter of the price?
Click to expand...


--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Yaesu FTV901R Transverter, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/
 
"Brian Soper" <brianpaulsoper@yahoo.com> wrote in message
news:3b2c5386.0405150441.5be92ceb@posting.google.com...
What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.
Click to expand...
You'll need a big torch to do that, because the heatsink will, well,
sink all the heat! Besides, solder won't stick to aluminum.

Probably the easiest thing to do is to tap it with a common size tap,
and screw an aluminum screw into the hole, but make sure the screw end
doesn't stick up above the surface of the heatsink. But since it's hard
to find an aluminum screw, maybe use brass, or just forget it and leave
the hole as it is, empty.


--
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I would suggest using a thermally conductive epoxy or other thermally
conductive adhesive to fill in most of the hole, but don't fill them all the
way to the top. When the component is installed on the heat sink, use the
heat sink compound to fill in the remaining gap between the component and
the thermally conductive adhesive filling most of the hole. This approach
assumes you don't wish to use the thermally conductive epoxy/adhesive to
secure the component permanently. If the component installation is
permanent, you can let the thermally conductive epoxy/adhesive completely
fill the hole and conform to the component.

You may also be able to use heat sink compound alone to fill the holes and
close the gap between the component and heat sink.

Good luck. Let us know if you try any of the suggested methods and have
success/failure.

--
- John

John Eric Voltin
Mechanical Engineer
Agile Technology, Inc.
jevoltin@agile-technology.com
512-633-0394

"Brian Soper" <brianpaulsoper@yahoo.com> wrote in message
news:3b2c5386.0405150441.5be92ceb@posting.google.com...
What can you do about drilled holes in heatsinks? I'm guessing that
they will cause heat transfer problems if an component is connected
over the holes. I'm talking about extra holes, in addition to the
component mounting holes. Can they be filled and still allow good heat
transfer? I was thinking that they might be able to be filled with
solder and a torch, but I'm only making an uneducated guess at this
possible solution. Would electronics solder (40/60) be the best for
this? I'd appreciate any help that anyone might offer. Thanks.
Click to expand...
 
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