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Is it good design to put SMT components beneath socketed DIP packages?
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technix:
For example, a 68010 on a mostly SMT board, can I socket the DIP-64 68010 and put the following items beneath it:
* Bus pull-up resistors, 0603x4 resistor packs,
* Bypass caps, 0603 ceramic caps
* Reset circuitry, SOT23-4 chips, SOD123F diodes and 0603 resistors
* Part of the level shift circuitry, a 74HC00 in SO-14 package and a 0603 resistor.

Even more daring, can I squeeze a DC-DC 12V-5V converter down there without interfering the chip? (TPS562200 in SOT23-6 + 0603 passives + EIA case B tantalum cap + a low profile power inductor.)
helius:
It was common to place bypass capacitors underneath DIP chips (and there were special variants of DIP sockets that contained pre-installed leaded capacitors between VCC and GND). Some of the other ideas can work, but the magnetics may cause EMI problems.
bloguetronica:
Hi,

IMHO, although it is not advisable to do so, it is perfectly doable. The reason behind this is that the socket will make the replacement of these components much more difficult. But if these SMD components are all passives (resistors, capacitors, etc), the chance of having to replace them is very slim, and it is perfectly OK to do so. Integrated circuits and oscillators should be placed elsewhere.

Kind regards, Samuel Lourenço
glarsson:
The placement of the components depends on the socket. All sockets are not equal, so changing socket model might require PCB layout changes.
bson:
You can also put all SMD parts that make sense on the other side, wherever is convenient after layout of the TH parts on the board.  The parts that wouldn't make sense would be things like indicator LEDs.  With corner holes and standoffs (the standard issue M3 stuff used to assemble PCs) it won't sit on the SMD parts when you place it on a table.  (Or the TH pins for that matter.)
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