Better transistor package?

JojoD818 · 12th March 2003, 03:32 PM

Hi!

I'm new in this forum, most of the time I just read and find it's very informative but now I need to ask a question.

I would just like to ask your comments on which is better or easier to keep cool, transistors in TO-3 package or the plastic ones (TO-247) for output of power amps.

Tnx!

Jojo

MGR · 12th March 2003, 10:00 PM

Hi

I am also from the Philippines,the better package is TO-3 but mounting wise the Plastic package is easier to work with.

MGR

JojoD818 · 13th March 2003, 05:38 AM

MGR,

Nice to know that we're from the same country.

I guess Ill just stick with to-3s this time.

peranders · 13th March 2003, 08:08 AM

TO-3 is ancient, not used anymore for new designs. Why? It's difficult to mount, that's the main reason. I think also that it's cheaper with plastic case.

Morph · 13th March 2003, 09:53 AM

Actually there are a number of new designs that use the TO-3 package. Although you are right that the plastic packages are becoming more common.

If you are making in amp that is gonna get very hot (class A) then the TO-3 transistors are definatly better at keeping cool.

peranders · 13th March 2003, 10:22 AM

Quote:

Originally posted by Morph
Actually there are a number of new designs that use the TO-3 package. Although you are right that the plastic packages are becoming more common.

If you really look inside power electronics (not just amps), manufactured today, TO-3 is very very rare.

JojoD818 · 13th March 2003, 10:45 AM

peranders.

so you are saying that its a good choice to choose plastic packaged transistors nowadays. i'll just be using it for an amp project.

tnx.

jean-paul · 13th March 2003, 11:06 AM

Rare because they are more expensive than plastic and more difficult to mount. TO 3 is a very good case for heavy applications considering it's thermal characteristics.

Same story as why DIL/DIP disappears: production costs. Although I missed the explanation of producers like they give with SMD components:

- "the market demands it"
- "it has lower lead inductance"
- "better RF characteristics"
- "it is to big"

janneman · 13th March 2003, 11:30 AM

Indeed Jean-Paul.

Another thing to note is that the package is only part of the story. Thermal resistance is much like electrical resistance. From the transistor chip to ambient air you first have to go from chip to package which has a certain resistance in deg Celcius/Watt, then to the washer, then to the heatsink, then to ambient. Each junction adds a thermal resistor in series. At the and you arrive at say .75deg/W for the TO3 and .80 for the plastic, not a great deal and easily compensated for by increasing the heatsink a little if it were critical. And it is only for interest in class A applications anyway.

Modern, wideband power transistors for audio are as far as I know all packaged in plastic.

Jan Didden

Morph · 13th March 2003, 11:36 AM

What about things like the mj15003/mj15004, its not true that all power transistors these days are in plastic packages just most of them are.

Some of the new power opamps from burr-brown are in TO-3 packages. I saw one with 8 leads! how about that for difficult to mount.

12th March 2003, 03:32 PM	#1
JojoD818 diyAudio Moderator Join Date: Mar 2003 Location: diyAudio Special Operations Center	Better transistor package? Hi! I'm new in this forum, most of the time I just read and find it's very informative but now I need to ask a question. I would just like to ask your comments on which is better or easier to keep cool, transistors in TO-3 package or the plastic ones (TO-247) for output of power amps. Tnx! Jojo

13th March 2003, 05:38 AM	#3
JojoD818 diyAudio Moderator Join Date: Mar 2003 Location: diyAudio Special Operations Center	Hello! MGR, Nice to know that we're from the same country. I guess Ill just stick with to-3s this time.

13th March 2003, 08:08 AM	#4
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	TO-3 is ancient, not used anymore for new designs. Why? It's difficult to mount, that's the main reason. I think also that it's cheaper with plastic case. __________________ /Per-Anders (my first name) or P-A as my friends call me

13th March 2003, 11:06 AM	#8
jean-paul diyAudio Moderator Emeritus Join Date: Sep 2002 Location: The Netherlands	Rare because they are more expensive than plastic and more difficult to mount. TO 3 is a very good case for heavy applications considering it's thermal characteristics. Same story as why DIL/DIP disappears: production costs. Although I missed the explanation of producers like they give with SMD components: - "the market demands it" - "it has lower lead inductance" - "better RF characteristics" - "it is to big" __________________ It's only audio

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

12th March 2003, 10:00 PM	#2
MGR diyAudio Member Join Date: Oct 2002 Location: Philippines	Hi I am also from the Philippines,the better package is TO-3 but mounting wise the Plastic package is easier to work with. MGR

13th March 2003, 09:53 AM	#5
Morph diyAudio Member Join Date: Feb 2003 Location: London	Actually there are a number of new designs that use the TO-3 package. Although you are right that the plastic packages are becoming more common. If you are making in amp that is gonna get very hot (class A) then the TO-3 transistors are definatly better at keeping cool.

13th March 2003, 10:45 AM	#7
JojoD818 diyAudio Moderator Join Date: Mar 2003 Location: diyAudio Special Operations Center	peranders. so you are saying that its a good choice to choose plastic packaged transistors nowadays. i'll just be using it for an amp project. tnx.

13th March 2003, 11:30 AM	#9
janneman diyAudio Member Join Date: May 2002 Location: Where Germany, The Netherlands and Belgium meet Blog Entries: 6	Indeed Jean-Paul. Another thing to note is that the package is only part of the story. Thermal resistance is much like electrical resistance. From the transistor chip to ambient air you first have to go from chip to package which has a certain resistance in deg Celcius/Watt, then to the washer, then to the heatsink, then to ambient. Each junction adds a thermal resistor in series. At the and you arrive at say .75deg/W for the TO3 and .80 for the plastic, not a great deal and easily compensated for by increasing the heatsink a little if it were critical. And it is only for interest in class A applications anyway. Modern, wideband power transistors for audio are as far as I know all packaged in plastic. Jan Didden

13th March 2003, 11:36 AM	#10
Morph diyAudio Member Join Date: Feb 2003 Location: London	What about things like the mj15003/mj15004, its not true that all power transistors these days are in plastic packages just most of them are. Some of the new power opamps from burr-brown are in TO-3 packages. I saw one with 8 leads! how about that for difficult to mount.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Can bias transistor mount on top(body) of output transistor??	Leolabs	Solid State	23	16th February 2008 01:35 AM
WTB: BUF-634 buffers in TO-220 package	KT	Swap Meet	1	24th July 2007 06:15 AM
transistor package	anton	Parts	8	11th August 2006 07:47 AM
wtb: AD815 in SIP package (EU)	Onvinyl	Swap Meet	5	18th February 2006 06:16 PM
complete package	spyder	Swap Meet	1	11th September 2002 01:43 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read