Great information- this is some real good stuff.
>>> [log in to unmask] 05/09/03 08:28AM >>>
Siggi,
We went down this path a couple of years ago and I think I can give
you a few things to keep an eye on. At that time, there really were no "off
the shelf" turnkey laser etch systems. Even when a vendor advertises this,
they usually build your machine from scratch and you have a lot of input as
to how you want the machine configured.
If all you etch is PCB's, a CO2 laser works well. You have more
safety concerns with a YAG and the CO2 has plenty of power. We use systems
with 10 watt CO2 and they work fine. We wanted a turnkey system with
conveyors and adjustable rails for different panel sizes. We use an in-line
process. We went to Apex, then all over the country to qualify a vendor. We
sent each laser etch vendor samples of our boards and serial number scheme
and had them etch them and send them back for testing. We ended up going
with Control Micro systems in Winter Park, Florida.
You will have to decide where to mark and what symbology to use.
Unless you have boards with lots of room, you will have to go with a 2D
symbol. On most PCB's these days, there just isn't room for a 1D bar code.
On our boards, we had white silkscreen check boxes already and because we
had different board colors and our reader vendors said that would allow for
consistent reader settings. Etching into a white silk screened box gives you
a dark-on-light symbol.
The laser-etch vendors usually won't sell you an etching/reading
solution. They say that you can use any reader. That means you have to run a
DOE on readers too. When we qualified each vendor, we brought them all in,
DVT, RVSI, Autoimage ID, Microscan. We were looking for perfect read rates
on our testing and both a serial and Ethernet connection. We also wanted a
unit that you didn't have to be a vision expert to run. We tested
light-on-dark symbols and dark-on-light symbols. We mounted the units on a
conveyor and ran multiple boards at different conveyor speeds. We read
on-the-fly. Each vendor performed relatively well. What we didn't check, was
what happens when you have one board light-on-dark and the next one
dark-on-light. This will be important later. Do yourself a favor - check
this!
We discussed our serialization plans with our board suppliers, laser
etch vendor and different reader vendors. We wanted to read-on-the-fly going
into our testers with conveyor mounted readers. We also wanted to use
hand-held readers at repair. When you read-on-the fly on a conveyor, you
have to have a consistent location to etch. This isn't that easy to find.
Once you find it you have to stake out that territory with the board
designers. There is always a cap, or something, that needs to go in that
location! We ended up putting a symbol on the panel, or board, in a
consistent location for conveyor reading and one on each board in the panel
that can be anywhere it can fit for handheld reading.
We bought our first system and had the vendor come in for
installation and training. You need to get engineers and technicians
involved in this process. A laser-etch system is NOT like a label printer.
Once you set up a laser-etch system, you leave it alone. If you have a board
jam down the line, you don't jack up the conveyor in the laser to clear it,
you adjust everything else but the laser!
Etching worked fine for a while, but then we started to have
problems reading the symbol. It turned out the white box had "orange peel"
or bubbles every now and then. When we went back to our board supplier,
essentially they said that the silkscreen wasn't a controlled
characteristic, so they couldn't guarantee the box would be perfect. Why
didn't they say this before - we weren't happy.
We had to go back to the CAD guys and have them remove the white
boxes and we etched directly on the mask. This gives you a light on dark
symbol. Shouldn't be a problem - right? - wrong. The reader was "optimized"
for dark on light and not light-on-dark. We had used DVT smartreaders and no
matter how the vendor tried to change the setting and software on the fly,
we still had reading issues switching from light-on-dark to dark-on-light.
We couldn't ECN the boards just for this change, so the engineers rolled
this change in with other changes, so now we were in reading hell with some
boards light-on-dark and some dark-on-light for a while. We ended up
requalifying all the vendors with the ability to read
light-on-dark/dark-on-light at will and a different vendor worked out best.
This was the AutoImage ID Hawkeye 15E (they were later bought by RVSI)
The technicians wanted something like a 1D reader - just put it on
the line and plug it in. 2D reading isn't there yet. We trained them all on
the DVT's and then had to retrain on the Hawkeye. The good news is he
Hawkeye is much more user friendly. The bad news is with Ethernet and serial
connections they all are expensive. You will probably spend more on readers
than the laser when you are done. We ended up going with a Welsh Allyn for
our handheld reader. The Ethernet capability was invaluable for debug. When
you have an issue, you need an image to send to the vender. We had the
Hawkeye folks add the ability to capture "bad images". This helped when
operations came back to us and said there were read-rate issues. We looked
at the images and found pictures of hands, pictures of the board put in
backwards, etc. We also found some real problems as well.
In the end, things worked out well and we have many more lasers now
in more factories. The process is still not "set it and forget it". New
boards come in, have to be qualified. You have to pay attention to the
symbols and make corrections as soon as things start to go south. In the end
it is a process that, like any process, you can perfect with a little
effort.
Good luck.
Regards,
Chris
-----Original Message-----
From: Zweigart, Siegmund [mailto:[log in to unmask]]
Sent: Friday, May 09, 2003 6:59 AM
To: [log in to unmask]
Subject: [TN] laser marking systems
Hello all
For a new customer we are looking into laser marking systems.
It should be able to mark bar code and 2D data matrix codes in the solder
mask.
We had some discussions with customer and some potential suppliers.
Some questions came up:
- What is better: Nd-YAG or CO2 laser (in the Nd-YAG process the
solder mask is removed down to the bare copper, with CO2 only the
color is changed).
- Do you have any experience with readability of the barcode after the
product was exposed to Air / humidity / soldering processes?
All input welcome
Siggi
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digestren. When we went back to our board sup
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or 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 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or 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 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
