Any interest in a CREE LED solder paste stencil?

112 posts / 0 new
Last post

Pages

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
Any interest in a CREE LED solder paste stencil?

Edit: stencil pattern is now on OSHPARK.COM as a shared project… http://oshpark.com/shared_projects/dw8NYoED

I’m thinking of having some solder paste stencils laser cut out of 3.5 mil Kapton sheet (much nicer than mylar, much cheaper than stainless steel). They would be around 1 × 4 inches and have patterns for the MTG, XRE, XML, and XPG. You would use them to neatly (hopefully) apply solder paste to stars for reflowing (align the cutout over the star, squeegee the paste through the cutout using something like an old credit card). Price would probably be around $3

Ignore the white marking in the image, the pattern is the red part. Also, ignore what looks like uneven gaps in the patterns… that’s due to image pixel limitations.

Edited by: texaspyro on 06/08/2014 - 17:23
MRsDNF
MRsDNF's picture
Offline
Last seen: 1 month 2 weeks ago
Joined: 12/22/2011 - 21:18
Posts: 13473
Location: A light beam away from the missus in the land of Aus.

Sounds good to me. Knowing my luck though it would run under the stencil. One for me please.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

PilotPTK
Offline
Last seen: 7 years 4 months ago
Joined: 09/04/2011 - 21:53
Posts: 1736
Location: Michigan, USA

texaspyro wrote:
Ignore the white marking in the image, the pattern is the red part. Also, ignore what looks like uneven gaps in the patterns... that's due to image pixel limitations.

And pay no attention to that man behind the curtain!

I am currently extremely busy with work. Please do not expect a response from me quickly. I will be dropping in as time permits, but the amount of time I can dedicate to responding to topics and PMs is very limited.

nickelflipper
nickelflipper's picture
Offline
Last seen: 1 month 1 week ago
Joined: 10/20/2012 - 09:31
Posts: 497
Location: Oregon

I’d be up for one. Could I talk you into adding an XML-Color? The stencils have been shrunk down how much from the actual footprint? and wouldn’t you leave off the overflow on the anode and cathode?

Kent

PilotPTK
Offline
Last seen: 7 years 4 months ago
Joined: 09/04/2011 - 21:53
Posts: 1736
Location: Michigan, USA

Cree's own datasheet recommends printing paste there..

I am currently extremely busy with work. Please do not expect a response from me quickly. I will be dropping in as time permits, but the amount of time I can dedicate to responding to topics and PMs is very limited.

nickelflipper
nickelflipper's picture
Offline
Last seen: 1 month 1 week ago
Joined: 10/20/2012 - 09:31
Posts: 497
Location: Oregon

PilotPTK, I stand corrected, it’s sleepy time.

Kent

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
nickelflipper wrote:
The stencils have been shrunk down how much from the actual footprint? and wouldn’t you leave off the overflow on the anode and cathode?

The patterns for the XML and XPG are what CREE recommends. I believe that paste on the nubs helps wet them and enhances their ability to wick out excess solder. These stencils are 0.0035 inches thick… you will be getting a MUCH thiner and more consistent layer of solder than any manual technique.

The XRE and MTG are a bit different. Mine have the full area under the the thermal pad pasted. CREE’s have a smaller area pasted on the XRE and four blobs under the MTG. They also have the overflow nubs. That should work better for the way we tend to use them… heavily overdriven and manually pasted and reflowed.

Probably won’t do the color XML and MCE any time soon… I might do a “weirdo LED” one later for other models.

nickelflipper
nickelflipper's picture
Offline
Last seen: 1 month 1 week ago
Joined: 10/20/2012 - 09:31
Posts: 497
Location: Oregon

texaspyro wrote:
Probably won’t do the color XML and MCE any time soon… I might do a “weirdo LED” one later for other models.
Still interested in the current stencil. Thanks.

Kent

ruffles
ruffles's picture
Offline
Last seen: 3 weeks 1 day ago
Joined: 07/09/2011 - 10:18
Posts: 1020
Location: California

Two for me please if this goes ahead. Thanks!


 

JohnnyMac
JohnnyMac's picture
Offline
Last seen: 1 month 3 weeks ago
Joined: 04/12/2011 - 16:03
Posts: 8859
Location: Eastern PA

2 for me as well.  Awesome idea!  I hate the application of the solder paste when reflowing.

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593

I ordered a test sheet of the stencils… should be here in a few days…

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
JohnnyMac wrote:
I hate the application of the solder paste when reflowing.

Plus, you can’t get a nice, even, controlled amount of paste using eyeball techniques. Even worse is trying to tin the pads with solder. Most people don’t realize just how little solder it takes to do it right… 3.5 mils is about the thickness of a sheet of paper. Hopefully the Sinkpad/Noctigon stars are planar enough to be able to handle it.

Rufusbduck
Rufusbduck's picture
Offline
Last seen: 1 month 4 weeks ago
Joined: 04/04/2012 - 15:34
Posts: 10389
Location: Golden state

Put me down for 2, please. It beats the hell out of pretinning and filing the center pad back down.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

relic38
relic38's picture
Offline
Last seen: 3 years 5 months ago
Joined: 12/28/2012 - 00:39
Posts: 3390
Location: Toronto, Canada

I almost always get too much paste on there, and have to press down on the emitter with tweezers o squeeze it out. I’m in for two. Can you get a price on Stainless ones?

Welcome the night.

My Reviews   My Mods    http://budgetlightforum.com/search?

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
relic38 wrote:
Can you get a price on Stainless ones?

About $100…

Pulsar
Pulsar's picture
Offline
Last seen: 1 week 5 days ago
Joined: 07/29/2011 - 00:41
Posts: 5848
Location: Maine

texaspyro wrote:
JohnnyMac wrote:
I hate the application of the solder paste when reflowing.
Plus, you can't get a nice, even, controlled amount of paste using eyeball techniques. Even worse is trying to tin the pads with solder. Most people don't realize just how little solder it takes to do it right... 3.5 mils is about the thickness of a sheet of paper. Hopefully the Sinkpad/Noctigon stars are planar enough to be able to handle it.

yeah... the only reflow i have done so far was using solder, not paste. it was a mess to say the least. surprised i did not kill it.

 

id be down for one

Bort
Bort's picture
Online
Last seen: 13 min ago
Joined: 06/01/2012 - 17:15
Posts: 7625
Location: Holding the proverbial flashlight

One

The Journal of Alternative Facts TM

"It is critical that there is a credible academic source for the growing and important discipline of alternative facts. This field of study will just keep winning, and we knew that all the best people would want to be on board. There is a real risk in the world today that people might be getting their information about science from actual scientists"

 

richnpc
Offline
Last seen: 1 day 18 hours ago
Joined: 07/17/2011 - 10:59
Posts: 333
Location: USA

I’d be in for one.

relic38
relic38's picture
Offline
Last seen: 3 years 5 months ago
Joined: 12/28/2012 - 00:39
Posts: 3390
Location: Toronto, Canada
texaspyro wrote:
relic38 wrote:
Can you get a price on Stainless ones?

About $100…


OK, I’ll stick with the $3 option and get a backup one. Big Smile

Oh, any way to add duplicate XM-L and XP-G stencils on the same sheet without driving up the cost much? Those are the ones to get used the most, and therefore get worn out first. Just a thought. I’d still order two.

Welcome the night.

My Reviews   My Mods    http://budgetlightforum.com/search?

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
relic38 wrote:
Oh, any way to add duplicate XM-L and XP-G stencils on the same sheet without driving up the cost much?

Based upon the size of the stencil sheet, it works out best with the four patterns on it. They are cheap, just buy more. With a little care, they should last longer than you…

relic38
relic38's picture
Offline
Last seen: 3 years 5 months ago
Joined: 12/28/2012 - 00:39
Posts: 3390
Location: Toronto, Canada
texaspyro wrote:
relic38 wrote:
Oh, any way to add duplicate XM-L and XP-G stencils on the same sheet without driving up the cost much?

Based upon the size of the stencil sheet, it works out best with the four patterns on it. They are cheap, just buy more. With a little care, they should last longer than you…


True enough, just had to ask to satisfy my curiosity Beer

Welcome the night.

My Reviews   My Mods    http://budgetlightforum.com/search?

Helios-
Helios-'s picture
Offline
Last seen: 1 year 6 months ago
Joined: 01/18/2012 - 21:12
Posts: 2099

Stencils!
Yep, interested.


Counterfeit 18650s, 2,<a href=“http://

chiefinspectorfinch
chiefinspectorfinch's picture
Offline
Last seen: 2 months 4 weeks ago
Joined: 09/27/2010 - 14:33
Posts: 555
Location: Croatia, country with kleptomaniac clero-fascist government

I was just thinking other day how neat would be to have stencil for xm-l. Interested !

Society is like a pot full of nuts and bolts, finest pieces always end up on the bottom...

 

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593

Test run of stencils have shipped and should be here in a couple of days…

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593

The test run of stencils are here! They work well… with a little practice. My first attempt at applying paste took around 6 tries to get it right. The next took two. The next two went without a hitch.

What I do is stick the star down to a table with a small piece of double sided tape… smaller than the star so the tape does not stick out past the edge and snag the stencil. I stick my finger on the tape a few times so the top is less sticky than the bottom. Keeps the tape on the table when you remove the star.

I put a couple of strips of masking tape across the stencil, align the pattern to the star, and stick the stencil down to the table with the masking tape. It takes a bit of practice to get the tension right so the the pattern stays aligned. A little stabilization with one hand can help keep the stencil aligned.

I put a little dab of paste on the edge of a strip of credit card material (You say you are a wise man that doesn’t have credit cards? Go to Kinkos/Fedex store and get a free payment card from the machine). Hold the strip of card at a 45 degree angle and swipe it across the stencil.

Carefully lift the stencil. If all went well you will have the pads covered properly with no bleed between them. You will be amazed at just how little paste is used. If you got bleed, misalignment, etc, wipe off the star, clean the stencil with alcohol, try again.

Lift the star off the double sided tape. You may have to scrape the tape off of the star.

Drop the LED onto the solder paste. I was able to test the LED with a meter before reflowing the star. There was no shorts between the power connections and the thermal pad and the LED lit up.

Reflow the star… I use a small butane torch. One thing is that I got no excess solder oozing onto the overflows to indicate that the solder flowed. Also the LED was perfectly aligned to start with and did not do the “floaty rotatey dance”. I looked for a tiny amount of flux bubbling out of the edges and a shiny edge of solder at the edge of the LED.

MRsDNF
MRsDNF's picture
Offline
Last seen: 1 month 2 weeks ago
Joined: 12/22/2011 - 21:18
Posts: 13473
Location: A light beam away from the missus in the land of Aus.

Nice. Is this a goer then?

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
MRsDNF wrote:
Nice. Is this a goer then?

It looks like it… I need to test the other patterns. So far I have only done XMLs.

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593

Ok, XRE’s and (probably) MTGs are real easy… you can do them blindfolded. The XRE stars that I used were DX non-Sinkpad style stars. All the others were Noctigons. I don’t have any MTGs to play with (frankly I don’t see much good in those things).

XPG’s are a bit of a pain. The apertures are quite a bit smaller. It took me 5 tries to get a clean print. Should improve with practice, but I only had one Nichia 219 to test with. The first try left one pad dry. I could have used the second through fourth prints if I took a resistor lead and cleaned up the slight bleed I was getting between one of the pads and the thermal pad, but I wanted to see what it took to do it with just the stencil. I should have cut a smaller width piece of Kinko-card for use with XPGs. The piece that I was using was too wide.

Also, I think that just holding the stencil in place with one hand works as well as trying to tape it down. The double-sided tape holding down the star works very well.

PilotPTK
Offline
Last seen: 7 years 4 months ago
Joined: 09/04/2011 - 21:53
Posts: 1736
Location: Michigan, USA

A little bleed through won't hurt anything.. The solder will snap back onto the pads as soon as it reflows - especially if its tin-lead.

One trick that really helps with mylar/kapton stencils is to set a few of the same-thickness stars around the one you're pasting.  It prevents the stencil from wanting to flop over the edges of the tiny star while you're squeegeeing the paste.

PPtk 

I am currently extremely busy with work. Please do not expect a response from me quickly. I will be dropping in as time permits, but the amount of time I can dedicate to responding to topics and PMs is very limited.

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593
PilotPTK wrote:

A little bleed through won’t hurt anything.. The solder will snap back onto the pads as soon as it reflows – especially if its tin-lead.

One trick that really helps with mylar/kapton stencils is to set a few of the same-thickness stars around the one you’re pasting.  It prevents the stencil from wanting to flop over the edges of the tiny star while you’re squeegeeing the paste.

PPtk 

I know that the bleed doesn’t usually matter, but I was testing the star/led before I reflowed it (if it tests good you know there are no opens/shorts). If both pads had bled to the thermal pad, I couldn’t test it that way.

Supporting the stencil with other stars should work really well. With the stencil flopping over the edge, it wants to bow the stencil upwards and you get more bleed/misalignment.

texaspyro
Offline
Last seen: 1 year 11 months ago
Joined: 04/29/2011 - 12:43
Posts: 4593

Also, I was using some pretty “low tack” masking tape to hold the stencil in place. If your tape is too aggressive you might damage the stencil when removing the tape.

Pages