Order of placing SMTs?

[Glenn Ashmore]

What is the best plan for placing surface mounted compinents on a board?
Should you place the bigger stuff, SOICs and D2paks first and then fill in
the resistors and caps or do the small one first? Or should you just start
and one side and work towards the other?

If you get a little shakey placing a D2pak you risk bumping several small
parts off their pads. OTOH it is harder to place the smaller ones once the
big ones are placed.

The only thing I know for sure is that coffee and Mountain Dew don't help.


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

 

[Michael A. Terrell]

Glenn Ashmore wrote:

The only thing I know for sure is that coffee and Mountain Dew don't help.


Glenn Ashmore

I don't know about the coffee but Mt Dew never bothered me. My hands
were rock steady and I drank a 2 liter bottle a day. It also helped
take the edge off my migraine headaches.

--
?

Michael A. Terrell
Central Florida

 

[Chris]

Glenn Ashmore wrote:

What is the best plan for placing surface mounted compinents on a
board?
Should you place the bigger stuff, SOICs and D2paks first and then
fill in
the resistors and caps or do the small one first? Or should you
just start
and one side and work towards the other?

If you get a little shakey placing a D2pak you risk bumping several
small
parts off their pads. OTOH it is harder to place the smaller ones
once the
big ones are placed.

The only thing I know for sure is that coffee and Mountain Dew don't
help.


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or
lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Hi, Glenn. I'm assuming you're doing this by hand. Manual pick 'n'
place is the same as automatic pick and place in this respect. Best
just to go from one side to the other. For P&P machines, that
minimizes head travel/time. For hand placement, going from the end of
the board farthest from you in to the edge closest keeps you from
knocking components or jostling the board. I'm right-handed, so I go
from the upper left to the lower right. Trying to place all of one
type of component all over the board before moving on to the next
component is false economy and an invitation to mistakes. Use some
double-stick tape, and affix and label the individual embossed tapes on
the bench beside you beforehand. You can then pull them out one at a
time as you need them. The printout of the component layout goes on a
clipboard behind the board you're working on. That's what works for
me, anyway.

If you've got an air source and a bin of spare pneumatic blivets, and
you're planning to do a lot of this stuff, you might want to try using
a venturi and a little Clippard push button valve to make a small
vaccuum pipette to pick and place the smaller components. With a
little practice and tweaking, it can speed things up over the tweezers
routine, especially when removing parts from the embossed tape. It
lets you pull individual parts one at a time right from the tape, which
avoids all kinds of problems.

I also find it helps to place a dictionary or other prop under my
forearm to limit the wobble while I'm placing. Great lighting and a
low distortion magnifier help, too. Make sure to clamp the board down
while you're working on it, but use something that won't cause the
board to bounce when you release it.

Being a coffee achiever myself, I try to limit consumption on SMT days.

I like this part:

"If I were going to make this my profession I might invest in a special
cable cutter for the 1/0 and 2/0 battery cable but I am only going to
make 15 or 20 cuts in my lifetime. I have found that a regular pair of
compound pruning shears makes a nice clean, square cut." from
www.rutuonline.com

Good luck
Chris