Heat Pipe Soldering - Laptop (thermal mod turns tricky)

[Kevski802]

There aren't many topics one heat pipe soldering here so I thought I'd share my first experience.

 

Here's a relevant Log from @iamdarkyoshi which I really liked and wanted to reference here also

I have a 2010 HP Pavilion dv7 4000 from 2010 i5 M450 with AMD Radeon HD 5000 graphics. Very excellent laptop, has been great since I got it for school and I have used in constantly until I built my first rig in December last year. It was unfortunately getting very slow and really struggling to stay cool.

 

I wanted to continue having a laptop however so I decided to get a copy of windows 8.1 off Kinguin ($25) and change out my boot drive for a SanDisk 120Gb SATA3 SSD ($45 bucks new). Along with a full fan/system clean (It had been about 3yrs since I last de-lint-ed the cooler fins internally).

 

Simple, but I'm sure you understand "well I might as well do that since I'm here" which usually leads to something brilliant or exhausting but interesting either way.

 

So I tore the laptop down, removed the motherboard and the lint stricken fan and air hosed everything.

 

Then I thought back to some things I heard in Linus' videos regarding thermal paste and how manufactures don't usually spring for the best stuff and thought well I'll use up my leftover paste from my new Hyper 212 and possibly improve thermal performance further.

 

When I removed the cooler from the motherboard there was a totally unnecessary amount of very dry putty looking thermal paste on the CPU and GPU (clearly degraded I thought). 

CPU side:

 

So I went about cleaning that mess up and I noticed how little solder was used to connect the heat pipe to the little copper plate that interfaces with the CPU. That's thin plate to be reaching out across the entire CPU and conducting all that heat to the heat pipe on the edge of the CPU. 

Top of CPU side:

 

I figured even though solder doesn't conduct as well as copper it's much better than air so I could improve the heat conduction to the pipe by adding a nice large fillet of solder between the heat pipe and the copper plate on both sides.

So, grinning at my seemingly clever improvement idea, I went about securing the CPU plate and mounting bracket in the vise out in the garage (it was about 8F outside so I didn't want to spend much time out there working). 

 

 

I then grabbed a torch and spool of solder and began to heat the assembly, continually poking it with the solder to check the temp. The solder began to melt on the copper plate and I happily filled the entire void with solder.

That'll do 'er!!

 

As I was admiring this, out of the corner of my eye I thought I noticed the GPU heatpipe sag very very slightly (the heat pipe from the CPU plate goes to the fin assembly which also includes the GPU heat pipe which goes to the GPU plate). After a sudden realization and at the very moment when I finished thinking "..oh no" the fin assembly slid off of the CPU pipe and it, the CPU fan mount plate attached to it, the GPU pipe, plate, and mounting bracket all went their separate ways as they hit the garage floor.

Now it had become a full rebuild project and I moved to the kitchen table because I was freezing.

 

Reattaching the GPU plate and bracket to the GPU pipe in the same location was easy because the solder left on the pipe marked where it was and I clamped it in place and did the same as I had with the CPU (except the first time I assembled it flipped 180 and had to take it apart and resolder).

 

Now that the brackets and plates were on I had to get the fins and fan mount plate back together.

 

The only problem was I would need to hold everything in the right place securely so it could all heat up without falling apart. So I put the CPU and GPU brackets back on the motherboard and decided to hold them in the correct position with the fin assembly and then secure them in that position in a fixture where I could heat them up.

 

But when I went to slide the fin assembly on it wouldn't fit! The pipes had expanded slightly from the high temps. I had read about this possibility and about possible exploding heat pipes but I figured they had to solder them in the first place so they must be able to withstand at least solder melt temps. It turned out it was very easy to gently re-flatten them with a pair of flat pliers so I could squeeze the fins on.

 

I then did a dry fit in the chassis to make sure I had it right:

 

To hold everything together securely and make sure the plates would be parallel with the mound brackets, pennies!! I took a block of wood and stacked up some pennies on it where the CPU and GPU would rest and screwed the brackets down on them (this picture was before I did the dry fit with the fins on the motherboard):

 

The full fixture looked like this:

 

I jammed some extra solder in the fins with the heat pipes for better contact:

 

I torched everything at first to get it all warmed up then I only torched the CPU bracket on and off just enough to keep the solder flowing on everything without overheating. I held the fan mount in place with some pliers as I soldered it back to the fins. And vio la!

 

 

And it fit!! New peas of thermal paste and all:

 

Boots fast!! Runs cool!! Some 8.1 driver trouble with the swithcable graphics possibly causing an HDMI external to run extremely slow but that's another topic. Also unfortunately I didn't run any stress tests before I started but I know it's working great. Better? I don't really know. However, I certainly wouldn't discourage anyone from trying this (with caution of course) and doing some tests before and after. I think soldering heat pipes is fairly easy if you know how to solder and in the future I might play around with them and try making a custom cooler (I can use our machine shop at work).

 

I'll run Aida64 or something soon and post here.

 

TLDR notes my thoughts:

-Heat pipe soldering works

-Wow they really move lots of heat!! (duh) They heat up very quickly and entirely so expect to secure every piece of an assembly or it will all fall apart when you heat one part.

-They expand but can be reshaped and be careful not to heat more than what you need to melt the solder (use ppe)

 

Hope my first topic is interesting to someone  excited to join the community!

 

[iamdarkyoshi]

Nice work!

 

Just an FYI, heat pipes are pipe bombs. And when they explode, they are very VERY loud. I'm surprised I still have good hearing.

[zMeul]

Could've used thermal adhesive

[Kevski802]

21 hours ago, iamdarkyoshi said:

Nice work!

 

Just an FYI, heat pipes are pipe bombs. And when they explode, they are very VERY loud. I'm surprised I still have good hearing.

I was really glad I read your log before I started! Thanks! Otherwise I may have had an explosive experience myself!

 

21 hours ago, zMeul said:

Could've used thermal adhesive

I probably should have  to avoid the extra effort. But I didn't have any and in the end it worked out. Also thermal adhesive only conducts around 8 W/mK and solder is around 60 W/mK. Also It might have been much harder to get the paste into the little crevices around the pipe where the solder just seeps in. Maybe doesn't justify the work but, eh, I liked doing it.

[incendery_lemon]

wow, great job managing to solder the heat pipes!  I am doing mod on a laptop heatsink but I went the route of thermal epoxy  not quite brave enough to solder them. thanks for sharing

 

[THe6410]

Very nice! the wood block & screws are a good idea of keeping a good hold on the hot pipes and all. ( gonna have to try that! :P ) 
I'm trying to solder an extra pipe on my laptop heatsink as well and am having trouble with it in a few ways and had some questions... Did you pre-cut the solder and just stuff it into the heatpipe fins? and the just heat everything up with like a heat gun and let it all melt?

Also is it bad if you overheat the heatsink to the point where it expands? Does anyone know if this will hinder the performance of the heatsink? My thought process was that if most of the liquid inside evaporated, causing the pipe to expand, that would technically make the pipe less efficient right? because there isn't as much liquid inside the pipe to transfer heat. or am I wrong with thinking that?

If anyone has some insight on this and could letme know that would be great!