Resistor downsizing - PCB space saving

Resistor downsizing - PCB space-saving.

The trend in commodity chip resistor sizes is to go smaller. That's not really a surprise, just like semiconductors the smaller the resistor the more you can get from a single ceramic sheet during manufacturing.

What is a little more surprising is that when some circuit designs are updated the resistors are simply ported to the new design.

The table below shows the trend in resistor sizes and shows that 0201 and 0402 sizes are now the most popular.

What this means is that less and less capacity is available for chips in the range 0603 - 1206, as new investment will tend towards the more popular chip sizes and existing larger chip size production is converted to these sizes.

It then follows that the pricing trend on the larger chip sizes will continue to go up, and while production is likely to continue on these larger sizes, this will be at a much smaller scale.

While many designs can simply move to the smaller sizes in the next design iteration, some applications need the larger chip sizes due to higher power dissipation.

So, what to do if you need higher power, but want to migrate away from the larger chip sizes and future proof a design?

Replacing larger chip resistors with parts from the WK73 and SG73 ranges

For higher power requirements there are two possible solutions: Wide terminal or pulse tolerant resistors.

Wide terminal resistors have an excellent power to size ratio as they dissipate much of their heat via the wide terminals on the device. Pulse tolerant resistors are designed to have as much film material on the ceramic substrate as possible so while being able to handle higher pulse loads than standard resistors of similar size, their 'reduced hotspot design' also means that they can dissipate more power in the steady state.

The above graphic shows that a typical 0805 or 1206 resistor can be designed out in favour of a smaller pulse tolerant SG73 in an 0402 size, or a WK73 wide terminal part in 0204 size.