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March 2000

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Subject:
From:
Finlay Buchan <[log in to unmask]>
Reply To:
Date:
Fri, 17 Mar 2000 15:15:17 -0000
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Jorge

I know that we manufacture pallets but so do a lot of other companies so
please do not regard this as spam.

If you *have* to place both sides of a pcb,and one side does not have fine
pitched components (less than 15 thou), think about using a 2 or more
aperture print placement reflow carrier.

In one aperture place a raw card, in the second flip the half processed card
then process. At the end of the line take out the completed card and send
the carrier back to the front of the line with the half completed card.

This makes the following changes to your comments

>Subject: Re: [TN] One side vs Both side
>
>
>   Dennis
>
>   From my manufacturing point of view I see the following:
>
>   One side pass once trough SMD process it is more productive
>   Both side pass twice trough SMD process that could be
> different ( glue or
> solder again ) it is less productive
>

Now in the same time - except for placement.


>   One side means one machine program one set up
>   Both sides means two machine program and two set ups ( more
> work, more
> time )

Only one set up

>
>   One side goes direct to production
>   Both side creates intermediate buffers ( more space ) and
> more careful
> during inventory days

No buffer stock except those half completed cards in the carriers.

>
>   One side uses solder reflow
>   Both side could use glue that is a less robust process with
> high defect
> rate than solder reflow

Both sides use reflow

>
>   One side means less handling, less opportunity for handling related
> problem
>   Both sides means more handling and more care must be taken

No change

>
>   One side means one stencil
>   Both side means two stencil or one stencil plus glue
> process that means
> more manufacturing cost

One Stencil

>
>   One side means no special attention to bottom side support
> of the board
>   Both side means special attention must be taken to the
> bottom side of the
> board since some components could be damaged by the boards
> support system

Agreed but carrier can be used to support flimsy cards
>
>   One side means one oven pass
>   Both sides means two oven pass that degrades OSP boards and causes
> solderability issues in wave solder process

No change

>
>   One side could use bare boards pilled up to loader the line
>   Both side requires magazine type loader
>

No change

>   I can't comment the cleaning ( wash ) and conformal coating
> point of view
> since I don't have experience in these areas, maybe others
> can comment about
> ...
>
>
>    I would say that both side process is more cost, less
> productive and less
> robust process but if the advantages of both side process is
> greater than
> all work that manufacturing will have or the size requirement
> is important
> for design of the product then both side could be used. Make
> a cost analyze
> and see by yourself which process is better for your company.
>   To produce a both side board with small size to be used
> inside a equipment
> that has a lot of space available make no sense for me, but
> if both side
> reduces the overall cost of your board or you can reduce the
> size of your
> equipment ( and if it is a marketing advantage for you product ) don't
> hesitate to go to both side process.
>
>   I hope this help
>
> Jorge Dourado de Santana
> Maintenance / Process Engr
> Microtec - Brazil
>


Just another angle - hope this helps

Regards

Fin

Finlay Buchan
Technical Director
Datum Dynamics Ltd           Datum Dynamics Inc
Tel +44 (0)1290 426200       +001 401 683 5300
Fax +44 (0)1290 426212       +001 401 683 3995
Email [log in to unmask]
Web Page http://www.datumdynamics.com

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