Looking for ducted heatsinks

[free_electron]

like the one below.

that one is from Fisher but extremely hard to get in the US... Fisher has no reps here and i need to order in germany , they don't do credit cards , it needs paperwork .. waaaay too much hassle.. especially to get me designing. i need a few of these in my hand fast ... it woudl 3 weeks from fisher just to get a few... that's way too long

it needs to be a reputable source since i need about 2000 of these ...  size wize 4x4cm or 5x5xm and i need 4 flat sides. that is inescapable...
i don't need to burn of that much heat but i need the duct to force air through it. ( and for other reasons i don't want to get into.. mechanical , board layout , and more. boards will 'wrap' around the tunnel with thransistors on 2 or 4 sides. )

[nctnico]

Did you check Newark/ Element14? They probably can get it through Farnell from Europe but you pay the extra charge.

[free_electron]

oh that's right. i forgot. newark partners with farnell.. good idea !

[nctnico]

Besides that... you said you don't need to get rid of much heat. Wouldn't it be possible to use the PCBs as heatsink? Maybe use surface mounted heatsinks like these:
http://uk.farnell.com/fischer-elektronik/fk-244-13-d-pak/heat-sink-for-d-pak-25-c-w/dp/4302424

[free_electron]

nope. i need a tunnel. the tunnel is also mechanical strength for the whole assembly. this stuff goes in burn-in ovens...

[Christe4nM]

I suppose what you are looking for is what you see in this video
That's at least what I had to think of reading your description, and is what I am looking for for quite a while now for a PSU project. At the 29:00 mark you can clearly see that its heat sink consists of two (longtudinal) parts screwed together. I don't know whether it's supposed to be one heat sink from two parts, or they use two heat sinks to form a tunnel one.
Unfortunately I can't help you finding that, since I haven't been able to find such a thing as of yet. So whatever it is you decide on, please let us know

[mariush]

Yeah, Farnell has them, but usually just a few pcs of each and the rest with lead times for extra pcs of about 40 days.  For 2000 pcs definitely talk to the sales team..

If you need them fast, it's worth paying that extra 20-40$ for them to send them to you. If they don't want to for some reason, I'm sure some forum members in UK would also be willing to help you - I'd be willing to help you out, but I'm not in the most convenient country to order from with our 24% VAT.

[nanofrog]

You might want to check out Aavid Thermalloy http://www.aavid.com/product-group/forced. 

[digsys]

We have all sorts of moulds for that sort of thing. For that quantity, our Aluminium supplier charges $1K, so it amortises out
quite well. They're set up to do that, so it can be pretty quick. And they usually have an engineering association Co to do any
cutting, drilling etc. Custom parts are very handy.

[free_electron]

The AAvid's are WAAAAY too big. the tunnel can't be more than 40mm high ! there is hundreds of boards that go in an oven. the space from board to board is 55 mm. 40mm tunnel + board thickness + thickness of transistors ( the transistors are mounted recessed in the PCB ) the tunnel is sandwiched between two boards

[krish2487]

If you are willing to spend a little time engineering such a duct yourself , I d suggest

http://www.heatsinkusa.com/1-813-wide-extruded-aluminum-heatsink/

You can even see other sizes as per your need.

They are pretty cheap and you can "create" a duct by placing two such extrusions vertically, fins facing each other.
Much like the maynuo electronic load shown in the previous post.

[nanofrog]

The AAvid's are WAAAAY too big. the tunnel can't be more than 40mm high ! there is hundreds of boards that go in an oven. the space from board to board is 55 mm. 40mm tunnel + board thickness + thickness of transistors ( the transistors are mounted recessed in the PCB ) the tunnel is sandwiched between two boards

They can do other sizes, either using other existing profiles or a custom design should you need it (BTW, what's displayed is constructed of 4x pieces of the same extrusion that are held together by the mounting plates for the fans). Couple of channels mounted together would also work, or if you're after a single piece, look for the term "hollows" (may be found under "others" for extruded profiles).

Worth a closer look IMHO (phone call may be the quickest way to get to the right information).

heatsinkusa.com is decent as well, as is R-Theta Thermal Solutions (located in Canada).

[Christe4nM]

Browsing Fischer's site it seems they do have a USA rep called Ctrends.com
http://www.fischerelektronik.de/en/contact-en/representations-worldwide/representations/usa-en/

Since Fischer has the LAM4 40x40 mm, which seems to be what you're looking for I'd at least contact Ctrends. If that doesn't work for you, try RS since I did find the a LAM4 at RS but not at Farnell. The latter isn't carrying the LAM series at all from what I can find.

[free_electron]

Ill give fisher another try. I found another option at thermalloy. I would use two u shaped heatsinks to form the tunnel. One  would be 6 cm wide and 3 cm tall , the other 6 wide and 1 cm tall.
Put them on top of each other ( the top one fins pointing down) and i have 4 cm.

The heatsink will lay flat on the pcb. The pcb will have openings milled in it so the to220 resistors and transistors actually sit recessed in the pcb and the pins are soldered 'sideways' to the pcb.

The key is i need a couple of pieces in hand quick. Fischer cant deliver. Aavid can. They have stock and accept credit cards. I will have em monday.
I want to start the pcb design .. I simply cant wait 4 weeks to begin just because a supplier is old-fashioned and needs paperwork and or has no local distri ...

That ain't the way the world moves forward... At least not in silicon valley. If you can't deliver you are out.