Author Topic: Distance of bottom layer SMD pad to thru-hole pads  (Read 1565 times)

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Offline ocset

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Distance of bottom layer SMD pad to thru-hole pads
« on: March 21, 2018, 03:45:26 pm »
Hello,
Please can you confirm that for a offline power supply board (50w) with surface mount components on the bottom, and thru-hole on the top,
the SMD pads must be at least 3mm away from the thru-hole pads.
I just wiondered if Wave and reflow soldering techniques have changed so that they can be closer?
 
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Offline ocset

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Re: Distance of bottom layer SMD pad to thru-hole pads
« Reply #1 on: March 23, 2018, 06:28:34 pm »
Thanks, i am not talking about regulations...i am speaking about the manufacture of the board in the cheapest way.
For a board with smd bottm, and thru hole top, it is difficult to  wave solder the thru-hole pins if they are too near to the smd pads.....i was wondering how far do the smd pads have to be away from the protruding thru-hole pins in order to make the wave soldering easy and cheap.

I am assuming that the smd bottom components get mounted first....in the manufacture (pcb assembly) process
 

Offline tautech

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Re: Distance of bottom layer SMD pad to thru-hole pads
« Reply #2 on: March 23, 2018, 06:45:13 pm »
As you can make your own custom pads I see no reason why you can't make the design very compact (same net) however the possibility of doing rework should be given high priority in any layout and sadly these days it isn't.  :--
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Can help with advice on Siglent equipment as time permits.
 
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Offline PCB.Wiz

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Re: Distance of bottom layer SMD pad to thru-hole pads
« Reply #3 on: March 23, 2018, 08:28:04 pm »
Thanks, i am not talking about regulations...i am speaking about the manufacture of the board in the cheapest way.
For a board with smd bottm, and thru hole top, it is difficult to  wave solder the thru-hole pins if they are too near to the smd pads.....i was wondering how far do the smd pads have to be away from the protruding thru-hole pins in order to make the wave soldering easy and cheap.

I am assuming that the smd bottom components get mounted first....in the manufacture (pcb assembly) process

Surely the one to ask is those actually doing the PCB assembly ?!
Wave soldering clearances I would expect to vary, depending on the direction of solder wave travel.
Typically they would place the SMD parts with glue-dots, then wave-flow the fully stuffed board last.
 
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Offline katy201607

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Re: Distance of bottom layer SMD pad to thru-hole pads
« Reply #4 on: March 24, 2018, 02:17:25 am »
 depending on the direction of solder wave travel is correct
Professional Electronic Engineer from PCBGOGO
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