Solder paste type

Inventry
UnlistMe
Candle Power Forums

Help Support Candle Power:

I'll just tap onto this and add, is there one that is considered optimum for thermal transfer (eg. for direct-to-copper) that doesn't break the bank? I've got the cheap DX stuff, which does most jobs fine, but if I'm reflowing onto copper sinkpads I probably should investigate paste that's designed for better thermal transfer?
 
RoGuE_StreaK said:
I'll just tap onto this and add, is there one that is considered optimum for thermal transfer (eg. for direct-to-copper) that doesn't break the bank? I've got the cheap DX stuff, which does most jobs fine, but if I'm reflowing onto copper sinkpads I probably should investigate paste that's designed for better thermal transfer?
Click to expand...

Most solders today are ROHS compliant and are predominantly tin, so thermal resistance differences are fairly minor between the various formulations.

Semiman
 
I assume that means lead-free? Any sources of ROHS-compliant paste that doesn't cost an absolute fortune? I just checked my local large electronics supplier, RS Components, and the cheapest lead-free I could find was $81 for 25grams :eek:

Getting sidetracked, but is there some threshold for level of manufacturing where below that threshold you don't need ROHS compliance? Pretty sure all of my components are ROHS compliant, it's just the solder that's the, um, sticking point.
eg. if you send one item that you've made to someone in Europe, will it be blocked for not showing ROHS documentation? Or is it only when you send a container of 1000 items? While I'm all for reducing lead, I'd probably have to make 100 boards to use the equivalent of one fishing sinker's worth of lead. And at my current rate, that'd take a few years...
 
SemiMan said:
Check out Digikey
Click to expand...
Well I found some reasonably-priced stuff ($24 for 35g), but then remembered why I never deal with Digikey (or Mouser for that matter); $35 shipping. Don't know why they bother having a .com.au version of their site when it's all in the US anyway. The search will continue...

Also found elsewhere some tin/bismuth solders cheap, but on reading up it sounds like they can have issues and their low temp (~135C) probably isn't suited to high-power LEDs.
 
Kiln-Dried Oak Wood for Pizza Ovens, 8-Inch Barkless Logs, Ideal for Ooni, Gozney, Solo Stove, and Other Wood-Fired Pizza Ovens- Approx. 15lbs
See price on Amazon
Kiln-Dried Oak Wood for Pizza Ovens, 8-Inch Barkless Logs, Ideal for Ooni, Gozney, Solo Stove, and Other Wood-Fired Pizza Ovens- Approx. 15lbs
Old Potters Kiln Dried Firewood - Cherry, 1100 Cu. in, 16-18 Logs ~ 8" x 2.5" Logs. Solo Stove and Cooking Wood for Grilling, Smoking, and Firepits, Cherry.
See price on Amazon
Old Potters Kiln Dried Firewood - Cherry, 1100 Cu. in, 16-18 Logs ~ 8" x 2.5" Logs. Solo Stove and Cooking Wood for Grilling, Smoking, and Firepits, Cherry.
Greenworks 24V 6in BL Pruning Saw w/Auto Oiler, Tool Only
See price on Amazon
Greenworks 24V 6in BL Pruning Saw w/Auto Oiler, Tool Only
Firewood Central Kiln-Dried PA Hickory – 8” Splits (Approx 39.5 lb) – Bold Smoking Wood for Pizza Ovens, BBQ & Fire Pits – Easy Light, Low Smoke, USA Sourced
See price on Amazon
Firewood Central Kiln-Dried PA Hickory – 8” Splits (Approx 39.5 lb) – Bold Smoking Wood for Pizza Ovens, BBQ & Fire Pits – Easy Light, Low Smoke, USA Sourced
39" Fire Pits with Wood Storage for Outside, Large Wood Burning Outdoor Fireplace with Chimney, Mesh Spark Screen & Fire Poker, Idea for Backyard, Patio, Party, Camping, Picnic
See price on Amazon
39" Fire Pits with Wood Storage for Outside, Large Wood Burning Outdoor Fireplace with Chimney, Mesh Spark Screen & Fire Poker, Idea for Backyard, Patio, Party, Camping, Picnic
2 Stroke Engines Oil Fuel Mixing Bottle 4 Ratios 32:1/50:1/40:1/25:1, Reusable Motorbike Motorcycle Lawnmower Brush Cutter Chainsaw White
See price on Amazon
2 Stroke Engines Oil Fuel Mixing Bottle 4 Ratios 32:1/50:1/40:1/25:1, Reusable Motorbike Motorcycle Lawnmower Brush Cutter Chainsaw White
Husqvarna 100000101 Classic Chainsaw Carrying Case
See price on Amazon
Husqvarna 100000101 Classic Chainsaw Carrying Case
MechMaxx Heavy Duty 3-Point PTO Powered Stump Root Grinder For 15-45HP Tractors With 34 Carbide Teeth, 6'' Cutting Depth, 24'' Flywheel Diameter, Model SG24 Orange
See price on Amazon
MechMaxx Heavy Duty 3-Point PTO Powered Stump Root Grinder For 15-45HP Tractors With 34 Carbide Teeth, 6'' Cutting Depth, 24'' Flywheel Diameter, Model SG24 Orange
MechMaxx Heavy Duty 3-Point PTO Powered Stump Root Grinder For 15-45HP Tractors With 34 Carbide Teeth, 6'' Cutting Depth, 24'' Flywheel Diameter, Model SG24 Green
See price on Amazon
MechMaxx Heavy Duty 3-Point PTO Powered Stump Root Grinder For 15-45HP Tractors With 34 Carbide Teeth, 6'' Cutting Depth, 24'' Flywheel Diameter, Model SG24 Green
PPOLB 7 Ton Electric Wood Splitter, 15Amp Hydraulic Log Splitter, Portable Electric Log Splitter for Firewood, Compact Horizontal Wood Splitter for Backyard, Garage, Cabin - Orange
See price on Amazon
PPOLB 7 Ton Electric Wood Splitter, 15Amp Hydraulic Log Splitter, Portable Electric Log Splitter for Firewood, Compact Horizontal Wood Splitter for Backyard, Garage, Cabin - Orange
As an Amazon Associate we earn from qualifying purchases. Product prices and availability are accurate as of the date/time indicated and are subject to change.
Just use silver solder for everything. The extra conductivity can only help, and the extra cost is inconsequential. If you can afford to spend $10-20 on a single LED, then you can afford to spend another $10-20 on silver solder that will last for years.
 
Pay shipping & I'll send you lead'd or RoHS solder paste. But for thermal efficiency, I suggest copper/tin/gold alloy solder, I'll send you some of that as well if you'd like.
 
FRITZHID said:
Pay shipping & I'll send you lead'd or RoHS solder paste. But for thermal efficiency, I suggest copper/tin/gold alloy solder, I'll send you some of that as well if you'd like.
Click to expand...

I think you mean Tin/Silver/Copper solder which is better than Tin/Lead, but in application, the difference will be extremely minor. The most conductive solder tends to be Tin/Silver, about 50% better than tin/lead with most of the Tin/Silver, Tin/Silver/Copper about 20-30% better.

Tin/Gold solders are only about 15-20% better than tin/lead and really not worth the cost for this application compared to Tin/Silver.



Oh, thought Rogue had started thread ... but since Videoman, yup don't need ROHS, good practice though.

Semiman
 
fyrstormer said:
Just use silver solder for everything. The extra conductivity can only help, and the extra cost is inconsequential. If you can afford to spend $10-20 on a single LED, then you can afford to spend another $10-20 on silver solder that will last for years.
Click to expand...

You must have some magic paste, paste wont last for years as flux component will dry out. Please note Lead free on copper boards will require a fair bit higher reflow temp to get a good bond
 
SemiMan said:
I think you mean Tin/Silver/Copper solder which is better than Tin/Lead, but in application, the difference will be extremely minor. The most conductive solder tends to be Tin/Silver, about 50% better than tin/lead with most of the Tin/Silver, Tin/Silver/Copper about 20-30% better.

Tin/Gold solders are only about 15-20% better than tin/lead and really not worth the cost for this application compared to Tin/Silver.



Oh, thought Rogue had started thread ... but since Videoman, yup don't need ROHS, good practice though.

Semiman
Click to expand...

Actually, I ment tin/copper/gold. I have a spool of it here & would happily send him some, along with water soluble OR NO-Clean paste of his choice.
& yes RoHS solders do require higher reflow temps, just make sure everythings clean and dry and you shouldn't have any issues as long as you don't over saturate the heat and cook the pill.
We have special 5 zone reflow ovens for just that purpose, but it can be done on a hot plate, toaster oven, or in gutsy attempts..... A clothes iron.
(I prefer an oven or proper reflow equipment.)
 
FRITZHID said:
Actually, I ment tin/copper/gold. I have a spool of it here & would happily send him some, along with water soluble OR NO-Clean paste of his choice.
& yes RoHS solders do require higher reflow temps, just make sure everythings clean and dry and you shouldn't have any issues as long as you don't over saturate the heat and cook the pill.
We have special 5 zone reflow ovens for just that purpose, but it can be done on a hot plate, toaster oven, or in gutsy attempts..... A clothes iron.
(I prefer an oven or proper reflow equipment.)
Click to expand...


I have not heard of tin/copper/gold used for regular soldering, sounds more like die attach. Gold is used in solder mainly for mechanical properties and the elimination of flux due to superior wetting. If you want high thermal conductivity, Tin/Silver/Copper is the best and it is not overly expensive. It is harder to solder with as (in addition to temp issues) most copper alloyed solders have poorer wetting.

Semiman
 
hey guys.. I'm just enjoying the conversation! Never even heard of tin/copper/gold solder before. As a EE, I enjoy these sorts of discussions more than debates over tints. :)

Is the thermal conductivity of solder significant when applying the average 3W LED? I would have thought that other parts of the thermal path would dominate the thermal resistance. Or is this more for special cases?
 
i use digikey paste, paid iirc $16 for a surringe full. but the trick is, the paste has to be kept in a fridge, all the time, didgiky recomends 2 day shipping for paste, they mail it in termal bag, with ice bag in it. and you should keep the paste in the fridge, with surringe held in vertical position, before using let it warm up to room temp, for about 8-10 hours.
 
Steve K said:
Is the thermal conductivity of solder significant when applying the average 3W LED? I would have thought that other parts of the thermal path would dominate the thermal resistance. Or is this more for special cases?
Click to expand...

I think the thinking is that the thermal path has the smallest cross-section at this point in the train.

I don't do any high performance modding or anything, but I just tin the pads with regular solder. When I solder it, I let it flow/self-center, and then push it straight down with an appropriate tool to squeeze out as much solder as I can from between LED and solder pads. This is probably along the same lines of "does it really matter?", but it makes me feel better about it, and it's MY light, so I do what I feel seems best to my ability.

With regards to the refrigeration of solder paste, I imagine it is to keep it from separating out, since you can't very well stir the contents of a syringe if it separates. BUT that is just a guess on my part.
 
bshanahan14rulz said:
I think the thinking is that the thermal path has the smallest cross-section at this point in the train.

I don't do any high performance modding or anything, but I just tin the pads with regular solder. When I solder it, I let it flow/self-center, and then push it straight down with an appropriate tool to squeeze out as much solder as I can from between LED and solder pads. This is probably along the same lines of "does it really matter?", but it makes me feel better about it, and it's MY light, so I do what I feel seems best to my ability.

With regards to the refrigeration of solder paste, I imagine it is to keep it from separating out, since you can't very well stir the contents of a syringe if it separates. BUT that is just a guess on my part.
Click to expand...

You are mostly correct, the paste is kept cold to preserve the flux however, I've used 3 yr old paste that was kept sealed with no issues, but moisture is the biggest issue with paste solders.
I use RoHS pure tin paste & tin/copper/gold water soluble wire for all my work. Its high conductivity, thermal, strength & corrosion resistances can't be beat. Not ti mention, with the gold alloy, tin whiskering is lesser of an issue,.... But to each their own. :-)
 
You must log in or register to reply here.

Latest posts

Back
Top