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Sasha Jevtic
11/08/05 12:37
  11/08/05 12:39

Read: 1167 times
Barrington, Il

Msg Score: +1
 +1 Informative
#103438 - thermal reliefs only ease soldering
Responding to: Suresh R's previous message
Suresh R said:
now my doubt is,
Should the thermal relief pads be used only at ground pins of components or even in vias which connect the top layer copper pour to the bottom layer copper pour (ground plane).

The purpose of thermal reliefs is to aid in soldering. A large copper plane serves as an excellent heatsink, making soldered connections to the plane difficult. Even as the pin on the IC heats up as you solder, the pad connected to the plane tends to remain cooler. If you are not careful, you either end up damaging the IC due to overheating, or wind up with a cold joint.

Given the purpose of the thermal reliefs, there is no point in using them for vias since you won't be soldering to them.

As you select the design of your thermal reliefs, keep in mind that you are basically trading off between two attributes: electrical resistance of the connection vs. ease of soldering. Calculate the resistance of your thermal reliefs and see what you think. Be careful about using them for connections that will be carrying a lot of current.

--Sasha Jevtic

List of 16 messages in thread
two layer PCB      Suresh R      11/04/05 23:56      
   +5VDC also drives PhotoMOS relays      Suresh R      11/05/05 00:13      
   Solid ground plane is needed!      Kai Klaas      11/06/05 05:18      
      what i have done is      Suresh R      11/07/05 10:19      
         what you have done ...      Andy Peters      11/07/05 11:36      
            Thermal relief's      Suresh R      11/08/05 03:09      
               You need a solid ground plane      Kai Klaas      11/08/05 08:03      
                  I want the best money can buy, but do no      Erik Malund      11/08/05 08:22      
                  Thermal relief in PCB's      Suresh R      11/08/05 11:24      
                     An illustration...      Kai Klaas      11/09/05 06:26      
                        went through the design but      Suresh R      11/10/05 04:46      
                           Thermal reliefs were demonstrated      Kai Klaas      11/10/05 05:30      
                           who are you posting to????      Erik Malund      11/10/05 06:14      
               thermal reliefs only ease soldering        Sasha Jevtic      11/08/05 12:37      
                  Resistance calculation for thrmal relief      Suresh R      11/08/05 22:35      
                     you better read .....        Abhishek Singh      11/10/05 05:56      

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