Triac BTB10 600BW replacement with BTA412Y 600B

[john_332]

Hi, I've got an old vacuum cleaner with a non-working speed control; after disassembling I have found that the leads of a Triac are broken.
The Triac in question is a BTB10 600BW, and I have around a BTA412Y 600B: is it equivalent? From what I see in the datasheets I would say yes, but I'm not at all expert with Triacs...

Datasheets
BTB10: https://www.st.com/resource/en/datasheet/btb10.pdf
BTA412Y: https://www.ween-semi.com/sites/default/files/datasheet/BTA412Y-600B.pdf

[picburner]

The BTB10 has a non-isolated mounting tab while the BTA412 is isolated.

[john_332]

That won't be an issue since the tab is mounted on a dedicated heat sink, without any connection.
What about the other data?

[Ian.M]

On the contrary, that may well be an issue - the BTB10  600BW has a thermal resistance to mounting surface of 1.5 °C/W and T_j(max) of 150 °C, but the BTA412Y 600B is 2.1 °C/W, and T_j(max) of 125 °C.  That means that the junction of the replacement will run 40% hotter (relative to the heatsink temperature) and it has less 'headroom' to do so.
 
Even though the replacement is a nominal 12A part, I suspect that it will burn out quickly if the load current exceeds 6A and is likely to fail sooner than one would like.   You can *probably* risk testing with this part but if the vacuum cleaner is over 1200 W (nominal), or the heatsink gets hot after several minutes of operation with unrestricted air flow, I'd certainly want to order a compatible non-isolated tab TRIAC for it.

[john_332]

Thanks Ian. I've soldered the BTA and changed the heatsink with a bigger one: it works but as you suspected it gets quite hot within a few minutes of operation. I think I'll leave it as it is for now, then when/if it dies...I'll order the correct one (it's super easy to replace).

[Ian.M]

The risk with that is it may kill the gate drive circuit when it blows.  If it a simple RC + DIAC circuit it probably wont do more than blow a gate resistor, but if its got an IC odds are it will take it out.

[john_332]

I've ordered the correct replacement...for less than 5 € shipped at home, it was definitely not worth the risk.
Thanks again, these are aspects I didn't even consider...that's exactly why I wrote "I'm not at all expert with Triacs" (and a lot of other things )

[john_332]

So...instead of a single BTB10 600BW, I received one BTA12-4 and one BTA12-6...I guess it's the same as with the BTA412, possibly even worse due to the 2.4 °C/W thermal resistance 

[Ian.M]

Yep, you almost certainly *need* that non-isolated tab TO-220 package to get the heat out of the junction to keep it under T_j(max), and the BTA12-6 has the same lower  T_j(max) of 125 °C as the BTA412Y 600B  you've got in there vs the original BTB10  600BW 150 °C.

As you are in a cooler climate and have upgraded the heatsink, you can get away with  125 °C  T_j(max) non-isolated tab, vs the original 150 °C  T_j(max) which you'd need for reliability in southern Europe summers with the original heatsink.  Always figure that OEMs won't over-specify anything unless they can get the higher spec part cheaper than the regular one!
 
Well at least you've got plenty of insulated package TRIACs if you want to play around with lower power mains phase angle control circuits!

[john_332]

Yep, you almost certainly *need* that non-isolated tab TO-220 package to get the heat out of the junction to keep it under T_j(max), and the BTA12-6 has the same lower  T_j(max) of 125 °C as the BTA412Y 600B  you've got in there vs the original BTB10  600BW 150 °C.

As you are in a cooler climate and have upgraded the heatsink, you can get away with  125 °C  T_j(max) non-isolated tab, vs the original 150 °C  T_j(max) which you'd need for reliability in southern Europe summers with the original heatsink.  Always figure that OEMs won't over-specify anything unless they can get the higher spec part cheaper than the regular one!

Well, since I paid for the BTB, I complained and the seller is now sending me the correct part.
 

Well at least you've got plenty of insulated package TRIACs if you want to play around with lower power mains phase angle control circuits!

  

[wraper]

On the contrary, that may well be an issue - the BTB10  600BW has a thermal resistance to mounting surface of 1.5 °C/W and T_j(max) of 150 °C, but the BTA412Y 600B is 2.1 °C/W, and T_j(max) of 125 °C.  That means that the junction of the replacement will run 40% hotter (relative to the heatsink temperature) and it has less 'headroom' to do so.

Triacs are rarely mounted on so large heatsinks and loaded so much where such small difference would really matter (it would make 6^oC Tj difference with 10W dissipation and everything else equal). Actually BTA412Y has 150 °C T_j(max) but BTB10 has 125 °C T_j(max). Also it has lower V_T at the same current, so will heat less.

[Ian.M]

I must have either misread the BTA412Y datasheet (or flipped to the wrong datasheet), as yes I see its T_j(max) *is* 150 °C.    That gives a little more margin . . .

[wraper]

I just edited the post above and it's actually better as you incorrectly wrote that BTB10 can handle 150^oC

[john_332]

So, in the end I received the expected BTB10 and proceeded to replace the temporary BTA412Y, just to be on the safe side.
In my tinkering with electronics I never had to actually consider factors such as thermal resistance! For what I need I usually am far inside these limits, but for a large production appliance for sure they try to save money in every way and push the components much more to their limits...
Thanks to all, I've learned something new