Sometimes we get PCB's in with defective(distorted) fiducials that the production equipment(printer, PnP, etc) does not recognize.
It would be great if there was a product out there to replace the defective fiducial.
I'm talking about an adhesive shiny/metal dot(.035, .050, or whatever size shape one needs) to substitute for the original fiducial. Just stick it on the PCB and go. I know it would be hard to place it exactly where the original fiducial was, but I imagine one could be placed close enough.
Anyone out there ever heard of this?
Is there a place one could purchase these "replacement" fiducials?
One of our former SMT Technicians used a component we pick and place for this purpose.
The component is a bond pad that is soldered to a ceramic PCB during SMT assembly. The assembly is now obsolete. I tried looking up the manufacturer's part number in our system for you but it's no longer listed there.
I encourage the SMT Techs and operators to reject boards with bad fids as nonconforming materials.
Hi Paul M, There are no silly questions but silly answers.. and here is maybe a few if I understand you correctly: If you consider place anything less than a 1.27mm (50mil) pitch component down or a chip less than a 1210, hey it maybe don't even work if we are talking about a 2.54mm (100mil)pitch component package and you still need to fulfill the IPC rules and get a good solder paste print and component placement & soldering. Don't even consider this "replacement fiducial" as an option!
As I see it (based on the limitation of detailed info you gave us) you have 4 options: 1. Try to tweak the fiducial camera settings in the program/machine: lighting, threshold, surrounding pattern, search area, inner/outer lighting (depending on what vision system you are using) and make sure that there are no similar surrounding patterns such like a test point that has the very same diameter as the fiducial nearby.
2. If it is HASL surface finish on the board (If Not skip to No.3 below), then an uneven surface will be at the fid's and pads. This will cause the light to reflect a strange pattern back to the fiducial camera and it will see dark spots in the fiducial area. If No.1 above didn't work and if it is only a few board's to be produced, concider rubb the existing HASL (thinned) fid marks with a simple eraser (back end of a pencil or eq.). This will in such case make the surface matt/dull and therefore the image to be even and bright, for the fiducial camera & recognition vision system.
3. If You have tried No. 1 & 2 above, consider contact your pcb manufacturer and tell them that you are Not going to accept this low quality, please make new ones. This only works if you can actually pinpoint that they have made a poor fabrication of your pcb:s.
4. Out of business. Unless...
I think you can make an easy calculation of the time consuming and the costs...
BTW. it could be interesting to hear what type of boards regarding surface finish, typical component packages on it and which type of SMT-equipment you have. And... you have not described exactly (in detail) the actual fiducial problem for us...
If You have any questions, please don't hesitate. Best Regards Ps. Sorry for my poor english and grammar. Ds.
Option 5. If you have thru-holes as Bert mentioned, and if it is plated even better, you still have a fairly good chance to proceed. As long as you know the exact coordinates. But this can be tweaked afterwords, the important thing is that you got the repeatable in placement. /Best Regards
BTW, Option 6. Bear in mind though, In the stencil printer if you run into a problem like this, it will not work with the holes...Only what's in the stencil... We have under some rare circumstances used 1-2 pad's on opposite corners and on very large component pads/apertures for this to work for recognition. Otherwise the search area could/will take the next wrong pad/aperture... Then the result will be a misalignment of paste to pad. /Best Regards
The PCB's are supplied by the customer. No options. The BOSS say's get it done, make it work, I don't want to hear it. My BOSS is a psychotic idiot.
The printer is a DEK with no options for manual fiducial over-ride. I think my idiot BOSS wrote the software for this machine. Friggin idiot.
Yea, I can reprogram the DEK and use pads/apertures for FIDS, but it's a pain in the ass for ONE or TWO PCB's, then I have to re-program it back for the good PCB's.... it's a pain in the ass, I got better things to do with my time.
The PNP has manual fid over-ride, so that's not a problem for 1 or 2 PCB's.
And yes, I've used the "pencil eraser" to clean up fid's.
Aviation? Who gives a sh*t where the product is used. Sheeeesh..........
Peelable solder mask works well. Hand dispense and peel off after. Paint sticks work OK, but it depends on the mfger of the paint stick. In both methods you hand apply after screen print. Your Dek can be taught pads to get by. You may have to teach board by board depending on how steady a dot you can dispense.
Why don't you create a seperate program using pads as fids. Then, the operators can load this program at the end of the run and print the boards with the bad fiducials. You don't have to keep altering the program, your boss can can go about his day being an idiot and everybody wins.
I don't know how accurately you're going to be able to put a replacement down. You could use BGA replacement pads, but that is a lot of time and the results will be shakey.
On the DEK, make a copy of your program and teach some pads or through holes as fids. For a given lot, the drill offset is often pretty close, so you print a couple, figure out the offset you need for the machine and you ought to be able to get those last 25 or so without too much greif.
I like the BGA replacement pad option the best. Reprogramming/programing? Forget it. That's what I'm trying to avoid. I'd be there all friggin day long, with all the loser "Labor Only" accounts we have. And oh, the paper work/floor documentation involved with multible programs? Oh the humanity. Makes my ulcer bleed just thinking about it.
I think this will be a non-issue for me in the near future.
You see, come New Years, I think I'm gonna tell my idiot BOSS to stick it, you know, where the sun don't shine?
That's gonna be my New Years resolution, to rid myself of higher up idiots. I deplore higher up idiots.....
I would refuse to use the PCB's if they are not usable as specified. The fiducials line everything up with the artwork...how can this accurately be done in a manual way?
Is the risk of reworking fiducials worth the cost of the potential financial impact of bad parts, or your company's reputation? I would look at the overall risk and (with financial impact) and use that to make your case to NOT use defective PCB's.
Aviation.Ha-HA-HA-HA. yes indeed who cares?! i got a bit of a belly ache now from laughing at the Fat Bastard's posting on aviation. a subject totally and utterly unrelated to the subject at hand.
I agree wholeheartedly with ya, Paul M. me chap. we're all pretty frustrated in this industry. Those of us ogres with enough insanity to do this type of work still and to top it off report to a psycho of a boss
I must say i do speculate if there is a Fiducial Repair kit anywere's, example, BEST electronics or some other outfit that sells PCB repair.
Dave F or any other laddies out there,you chaps know if this exists??
Paul, For the Dek and following equipment - seperate all the "bad fid" pcbs and process them seperately. Drill a hole as accurately as you can through the bad fids making sure you leave some white area around them. Set up and run a seperate program using black fids. I do it all the time.
This doesn't sound like standard processing to me... having to set up a separate program, drill holes, etc... to use bad boards from a supplier. If the supplier was a truly good supplier, they would send replacements ASAP and fix the issue.
I don't think yer getting the picture here. These boards are supplied by the customer. They are "Labor Only" accounts. We have NO control of the PCB's or any of the parts for that matter. These Labor Only customers show up at the back door and drop off a dumpster full of shit and asked the IDIOT boss if we will build it, you now, turn our dumpster full of shit into a gold brick? The IDIOT boss (in which, by the way, is the owner of this pop stand) say's yes because of dollar signs in his eyes (he has no clue on WHAT we even do here, let alone HOW it's done). The BOSS orders the LOWERDOWN folk to build it, under budget, whatever it takes, don't complain and JUST GET IT DONE.
We do not have an option to reject these PCB's. It's not a matter of shit-canning the crappy board supplier and getting a better one.
Is this clear? Do you understand now?
And oh...... I did get your PM's, I am NOT looking for a better board supply house. Just trying to get a bandaid on this gaping wound called "Fiducial-Replacements".
The other thing you could do is fit the cameras with a catseye lens. With my way all the data says the same apart from the fid diameter/shape and logic off/on. Just as accurate as any other method, a lot cheaper - cost = 1 drill, less nerve racking and much, much quicker.
Paul, My sincere apologies for striking a nerve - that was not my intent. I do not work for a board house, nor am I pushing anything on you. My comments only come from my history of having to use parts that made manufacturing a nightmare. I do understand what you mean about a customer that dumps all the parts on you and says build it - its frustrating as hell when your company accepts jobs with only dollar signs in their eyes and expects miracles. Again, my apologies. I wish you the best of luck.
If the machine or machines couldn't recognize the fiducials, you can grind it with a fiberglass eraser. If the fiducial are missing you can use tooling holes, and/or via holes. You can verify the hole size and tolerance on the PCB assembly drawing. Also, this drawings provide the coordinates with respect of the absolute PCB zero.
I have read all the replies here and have yet to see this one which I know works when our fids are HASL and distorted, thus unable to seem uniform enough for the vision systems on our MPM's or MyDatas to see them clearly.
Using a stainless steel needle pick, scratch the entire surface of the fids which then reflect light more evenly making the dark areas appear brighter.
It really does work....give it a shot.....cheap and easy and no re-programming for you!