Right, always visit the assembly house so you can understand their proces=
s.

The automated placement of SMD components is a ONE-SIDE process for most=20
assemblers. THis is because the stencil process is a one-side process,=20
using gravity to keep the devices in place.

People who have components on both sides have the second side assembled=20
by hand. Few shops can reliably mount SMD components automatically on=20
both sides, and ever fewer are located inside the USA.

I always mount SMD on top side, then install bottom SMD manually,=20
finally top or bottom sided thru-connectors manually, I have almost NO=20
confidence in SMD conectors.

--Bob

Roland wrote:

>Well, I visited an assembly house on friday for my first auto place job,=
 and was told, if possible, to keep all componenets on one side only. I h=
ave a mix of smd on top and bottom, and leaded on top, like I see on many=
 boards.=20
>
>But, if you keep all smd on one side, then they only need to stencil the=
 solder paste once, and possibly also reduce the stencil cost. Also, if y=
ou keep all smd on the top, then there's no need for the glue on the unde=
rneath to stop components falling off during the reflow.
>
>It's best to visit the guys first before you lay the board, to see what =
equipment they have, and their recommendations. No need to fight with the=
m afterwards. Also check what size pads they require for various packages.
>
>regards
>Roland
>
>
>
>
>At 06:32 PM 15/10/2005 +0200, you wrote:
> =20
>
>>>	What is the normal procedure for assembling boards? Do you guy just
>>>put the components where you need them or you try to think how to simp=
lify
>>>assembly to lower the costs? (the components where you need them, but =
off
>>>course always with no constraint violations).
>>>
>>>	Well... That's about it. Any comments?=20
>>>
>>>     =20
>>>
>>Hi,
>>
>>Yes, I always try to put SMD components on the bottom side and through =
hole=20
>>components on the top side. If I have to put a component, like a LED fo=
r=20
>>example, on the top side I choose a trough hole instead of SMD to keep =
assembly=20
>>cost down - SMD on one side only.
>>
>>Regards / Ruben
>>
>>
>>
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
>>Ruben J=F6nsson
>>AB Liros Electronic
>>Box 9124, 200 39 Malm=F6, Sweden
>>TEL INT +46 40142078
>>FAX INT +46 40947388
>>ruben@pp.sbbs.se
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
>>
>>--=20
>>http://www.piclist.com PIC/SX FAQ & list archive
>>View/change your membership options at
>>http://mailman.mit.edu/mailman/listinfo/piclist
>>
>>   =20
>>
>Regards
>Roland Jollivet
>
>
> =20
>


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