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

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

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

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

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

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

  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

  One side means one oven pass
  Both sides means two oven pass that degrades OSP boards and causes
solderability issues in wave solder process

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

  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

 

> -----Original Message-----
> From: Dennis Ward [SMTP:[log in to unmask]]
> Sent: 17 de Março de 2000 08:54
> To:   [log in to unmask]
> Subject:      [TN] One side vs Both side
> 
> Good morning everyone,
> 
> Question for all you manufacturing gurus. Is there a
> significant advantage, cost wise, to keeping all the components
> on the top side of the board versus placing components
> on both sides?
> 
> Now I do know that they are some NRE cost, but is it
> significant? In the past I was taught you should try to
> keep every thing on top. But it seems that high density
> double side boards are very common. There doesn't
> seem to be as much emphasize on consolidating all
> the components on the top side.
> 
> As an example if you quoted two boards - all things
> being equal except that one was populated on the
> top and the second board was populated on both
> sides what would be the cost difference (if any)?
> 
> The reason I ask is that I am laying out a board
> that I may be able to squeeze everything on top.
> However I'm tempted to just throw discretes on the
> bottom of the board. The engineer asked what was
> I going to do. I told him that I'd try to keep everything
> on top. He then asked "why"? I answered it would be
> easier to manufacture, inspect, debug, eliminate some
> manufacturing steps and eliminate some cost. But I
> started thinking and wondered if my thinking was backwards
> and these concerns are negated with the advance of
> technology.
> 
> Anyway, any advice would be greatly appreciated. Also
> I would like to take a moment and thank everyone for
> their particpation on this forum. It has proved extremely useful
> for me personally. Enough so that a few strings of humor well
> not affect my judgement as to the value of this forum. Actually
> I enjoy hearing some of the "old timers" discuss the days of tape
> and exact-o knives - personally never had the pleasure.
> 
> Thanks
> Dennis Ward
> Net to Net Technologies, Inc.
> 603 427-0600
> [log in to unmask]
> http://www.nettonettech.com
> 
> ##############################################################
> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
> ##############################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
> following text in
> the body:
> To subscribe:   SUBSCRIBE TECHNET <your full name>
> To unsubscribe:   SIGNOFF TECHNET
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> additional
> information.
> If you need assistance - contact Keach Sasamori at [log in to unmask] or
> 847-509-9700 ext.5315
> ##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################