Handle with care: want better boards? Treat your films better. (Better Phototooling).

WHEN WORKING WITH diazo and other phototools, film handling and first-quality finished boards go hand in hand. If your technicians are working with a phototool that has been damaged, you can expect the PCB will require a generous amount of touch-up. Worst case, you may have to scrap it altogether.

With finer lines and spaces, smarter film handling and cleaner production areas are more necessary than ever. Remember, anything that unintentionally blocks light will cause a defect on the board. Deep scratches on a phototool prevent light from transmitting properly to the dry film resist or LPI ink on the board. The result is a defect.

Let's review steps for maintaining a clean and organized production area.

* Always place artwork/film on a flat, uncluttered surface.

* Scratches come from pressure, motion and the slightest bits of grit, dirt, dust or other foreign materials.

* Good lighting is critical; be sure the artwork technician's worktable or light box is large enough to hold the film and has extra space for turning and positioning the artwork. This will simplify inspection and touch-up.

* Never store films with emulsions exposed to each other; this can damage both films. Avoid problems by placing films emulsion to base; or use a plastic-coated or other cleanroom style paper to separate them.

What technicians wear on the job can put production at needless risk. Train staff to be aware of the common-sense things that they can do to reduce board rework and scrap.

* When working with artwork or doing inspections, technicians should not wear watches, bracelets, rings and other jewelry that can scratch a film's emulsion. Buttons can also scratch. See that diamond rings are covered with tape.

* Easy on the hand lotions; lotions that come in contact with the artwork can impede the touch-up inks from properly adhering to the film.

* Avoid wearing clothes that shed fibers.

* Hair nets, smocks, beard/mustache cover-ups, gloves and booties significantly reduce board touch.

* Tacky mats dramatically reduce dirt brought in by shoes.

Here are tips on perfecting your technique and film handling.

* For liquid film cleaners, always apply the cleaner to the cloth and don't squirt the cleaner directly on the film.

* During touch-ups of the phototool, remember that Exacto knives leave very fine polyester chips and debris that can cause scratches and block light.

* When using touch-up opaqueing inks, make sure the film cleaner does not smudge, smear or remove the ink when cleaning the film. (Most liquid film cleaners are solvent-based). Also, many film cleaners are flammable: too much pressure can cause a fire. I have seen this happen!

* When squeegeeing the film after it is registered to the panel in the exposure unit's vacuum frame, work from the center of the board outward, not back and forth. Be careful: too much pressure can alter the registration. Avoid slamming the squeegee against the artwork. This can dent or crease the film or damage the photoresist.

* Within the photoresist imaging department, allow enough room to place the phototools on a flat surface and away from the panels to be imaged. Beware of the PCB panels' sharp corners.

* When transporting films, support them as best you can. If they are large, loop the bottom edge up to touch the top edge--keeping the emulsion surface inside and protected--and pinch the top and bottom. Do not crease the middle.

* Some shops make use of Plexiglas boxes and stiff vinyl zippered pouches or sleeves to carry films; that's an effective way to prevent nicks, bends and half moons.

* Always remove films from a file folder carefully; pulling film out from under multiple sheets can damage them.

* Make this a habit: the first thing to do is inspect artwork before imaging; the last thing to do is reinspect the artwork before returning it to the file folder.

* If you can "hear" your films in your production areas, they are more than likely being mishandled. Observe your photo department: if technicians are aggressively pulling the phototool films off the panels, I suspect you can "hear" the film too. This treatment will stretch pin-registered tooling holes and most likely result in a crease or half moon where your hand or fingers grab the film. Even if you bypass the pins by using tape, pulling/yanking the film off the panel can cause creases or "moonies." If your company uses registration pins, always lift the film off the pins carefully; never pull the film off aggressively.

* Always clean films before, during and after use.

Some companies squeeze the budget on their photolab and artwork generation area, and then spend plenty on their yellow room/PCB exposure operation. The quality of the finished board depends on quality phototools from the lab. The front-end operation directly affects the back-end. While pressure to get boards out the door can be overwhelming, remember how costly do-overs and scrapped products are. Giving techs the power to stop production for 15 minutes for touch-ups early can save hundreds in wasted output.

JEFF JARVIS is senior territory manager at InteliCoat Technologies (intelicoat.com). He can be reached at [e-mail].