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Aug 14, 2018 | Vlad, Reduce your aperture opening in the stencil, this will give the stencil a good seal around the specific area of concern. In a wave solder environment, solder balling top or bottom surfaces in a wave pallet is caused by excessive flux burning off too quickly or becoming trapped. Once the pallet/PCB hits the molten wave, a bunch of miniature explosions take place that creates solder balling. Maybe a combination stencil & profile?? My stencil Guru here at my Oregon facility can assist you if needed, reach out to me offline if needed...
Mar 6, 2018 | Thanks.,
Feb 28, 2018 | Stencil-less printing? MY500 on a NPI/Proto line makes a lot of sense and can really cut down on costs and downtime due to stencil revisions/issues. Especially once you have a 250 line BOM loaded on the line and you find out the stencil has a couple of critical apertures incorrect, change the MY500 program and keep running, or reorder the stencil and either tear down the entire job, or hold up an entire line for at least a day.
Mar 1, 2016 |
Feb 3, 2016 |
Jan 28, 2016 |
Feb 11, 2015 | stencil/printing machines for solder paste I can buy approx 1000 stencils (cost includes next day delivery) for the price of a MY500. With a stencil, I can use WS paste and any other paste for that matter. The MY500 only jets certain paste from specific manufacturers. It is VERY VERY rare that we cannot get the proper solder volume with a stencil (the first time) and we have over 2000 active SMT assemblies. The MY500 is a great idea but I just cannot understand how it could be cost effective in any arena at this point.
Aug 10, 2014 | Thanks
Aug 1, 2014 | Check attachments.
Nov 5, 2013 | Stencil Life Identification I track all of our production daily in an excel spreadsheet that I use to calculate the OEE. I added another tab and use it to automatically calculate remaining stencil life of each stencil. I replace my stencils after 25K cycles, (prints). Things to take into consideration, I chart my production in single assemblies, so I created a formula to revert these back to panels. Then I use an If/Than statement to trigger a cell flag from "Safe" to "Order Stencil", (changing the color of the cell to RED, when the stencil life falls below 10%). =IF(Q5>10%,"SAFE","ORDER STENCIL") I like tracking it this way
Oct 17, 2013 | But where does it go, that it needs to be refreshed or replenished on the stencil? Does that "just like wax" product wind up in my solder joints, no matter how small the percentage, and would it then qualify as a contaminant? I heard there are some (nano)coatings that are baked on during the production of stencils, and some are wiped onto the stencil by the end user. Those wipe on products I worry about just a little, as in, where does it go that it needs to be replenished on the stencil? I think that bears some thought. Maybe someone with expertise on these coatings can chime in, maybe
Feb 18, 2013 | We have some Vectorguard stencils and frames. I am having issues with one of the frames. And need a little guidance. A stencil is on the frame, and we can't get it off, the operator heard a pop while putting the stencil on the frame, now we hear air while trying to remove it. I have repaired this frame in the past, replacing one of the inner hoses, but cannot repeat the magic. I know I need to isolate on which side the air leak is...can't tell as it sounds as if its coming from a corner or two. Main thing is getting the stencil off without damage. Any ideas would be most appreciated.
Feb 15, 2013 | Small apperture release from stencil Hi MikeS, I didn't post all the information, because I didn't want to mislead you. I wanted to see your way. We tried 3mil and 4 mil stencil using type 4 paste. It was hard to get the right aspect ratio and that;s why we did it on Nickel stencil - aspect ratios are different for Nickel stencil
Dec 15, 2012 | solder paste stencil life Normally paste manufacturer specifies stencil life of a paste is 10 hours. the question is, if i run a continuous manufacturing for 40 hours, we will be adding 250 g of paste for every two hours. The addition of 250 g will be mixed with the paste which is already available on the stencil. After first 10 hours of manufacturing, do we need to remove all the paste in the stencil and scrap it?, currently the practice is we keep on adding till the end of production. since this goes by addition mechanism, there may be molecules of paste which has applied 12 hours before. any thoughts in this?
Jul 5, 2012 | The PCB has 9 QFNs, distributed arround the whole board, but the ones in the edges are the ones with the problem. My stencil is 0.005" (I use to have a 0.006"), yesterday I realize after talking to my vendor that the stencil is manufactured in 2 steps because the frame does not fit into the machine , so they cut half the stencil + rotate the frame + cut the other half, I'm guessing that may cause such inaccuracy... dont you think so? anyway I will send the stencl and a board the them to check if the PCB or stencil is according to gerber file.
Nov 17, 2011 | What is the best way to keep ESD totes clean? We use both the blue static dissipative and black conductive ESD totes to store/transport our electronic assemblies. Our problem is that they get dusty/dirty and periodically need to be cleaned using ESD cleaner and a paper towel. Being that human nature isn't what it should be, rarely do people take the initiative to clean their totes before use. Some people lay a Kimwipe on the bottom, but doubt that this is acceptable from an ESD standpoint. Since reminding has failed, one idea was to get a "dishwasher" of some type to clean small batches regularly, but what type of detergent
Aug 31, 2011 | Cleaning Vapor phase or vapor degreasing cleaning for electronics is simple technology that holds merit on process situations like you described. Easy and quick to set up and process with today's modern equipment you can be up and running in no time once the machine is on your floor. The hard part comes from matching the flux to the cleaning solvent. Many of the newer flux and solder paste formulas used today are very resistant to vapor phase cleaning. OA flux formulas are out as they do not clean with vapor phase cleaners. To compound this flux selection process the number of available vapor
Jun 29, 2011 | Hello all I have used a couple of types one of them only clamped on two sides and you used a wrench and screwed the bolt down till it was tight ( what is tight) and there was no fram at all around the stencil so people got cut. the second one we used uses air pressure to do the clamping and pulls from all four sides much better and has a plastic fram around stencil so no one gets cut by the stencil takes more space but i can fit two plastic framed stencils in one spot the full fram used so it saved me some space Goog luck
Apr 22, 2011 | Beaker Scale Testing for flux cleaning chemistries/surfactant Hi, I am doing my master degree in flux cleaning process for flip chip assemblies and required to establish a new receipt for flux cleaning. currently, i am doing screening process for the parameters involve ; temp,pressure, surfactants, speed and angle of penetration using inline cleaning machine . Is there any other ways to evaluate the chemical compatibility for flux cleaning instead of directly tries it using the cleaner machine? It will be a waste to use lots of chemical just for screening. I have found a paper that use beaker-test-scale method for chemical compatibility (Cleaning RMA Flux residue
Aug 21, 2010 | The paste you dispense will not solder the same as the one you use with a stencil. The paste for the stencil will have a higher metal content. I was not working with dispensing as small as you are, but after evaluating the cost of the stencil vs. longer run-time on the machine when dispensing , keeping multiple viscosities of paste, and the cost of the dispensing equipment, I decided the stencil was still the best solution for me (even with proto runs). This is just what I decided for my shop and doesn't mean it is the best solution for yours.
Jan 26, 2010 | Really Need Electroplishing of SMT Stencils? Dear SMTNetters: Based on your experiences is it really necessary to have today's YAG laser-fabricated stencils electropolished? I undertsand that this "requirement" is a carry-over from the days of CO2-fabricated lasers where the hole wall quality was less than desirable......... (There is some strong opnions on both sides of this argument) We use a SS stencil for small proto runs of less than 20 pcs, most thicknesses of stencils is 4-6 mils in SS. For UFP we are using nickel. Your comments are welcome.....
Nov 25, 2009 | The design of the opening apertures for the glue stencil and the metal thickness.Its is very important. The Engineer of the stencils supplier have to look into the height of the components and the gap of the 2 leg(pads)and give the assemly house an suggestions what stencil thickness should be used 0.007" or 0.008" or 0.010" You can contact me at email@example.com. I can look at your gerber files and help you to create the glue stencil work perfectly for you.
Nov 17, 2009 | Anyone else?
Nov 12, 2009 | Stencil Printer? appears to only carry the clam-shell type. If you look carefully at the photo of the ZelPrint you will see the PCB on the left hand side. The PCB has a thin film of polycarbonate pulled across it for alignment. The PCB (and polycarb) is slid to the right under the stencil and then lifted up to the stencil. The stencil does not move. After you squeegee the paste onto the board (covered with the polycarb) you lower and move the board left, back to the starting position. Now you can do a good alignment of the board by using the left-right, up-down, and rotation knobs. Because the paste
Sep 25, 2009 | Stencil thickness 0.5mm pitch QFP's are typically mixed with large components on all of my boards. I usually use a 6 mil stencil with a minimum aperture width of 10 mils. Normal aperture size is 10 x 50 which causes shorts about 20% of the time. A recent purchase of a used LSM height measurement system shows paste height of 7.3 to 8.2 mils. To compensate for the additional paste height, I could go to a step stencil for the QFP, reduce the aperture to 10 x 40 or go to a 5 mil stencil and take a lot of time increasing the paste on the rest of the parts. What are you doing to solve this problem.
Jun 16, 2009 | Hi, If your using NXT to place these BGA's then you must be doing large runs. BGA's are the most easy part to place, and don't worry about them. Just stencil paste down for them as any other component. But we use 1:1 reduction on our stencil, so we don't get paste release issues. Also, we use electroform stencils, as DEK make them cheap, and they are so much nicer than any other type of stencil we have used so far. Don't know why you would want to use just flux, on such an fast line, when pasting them will be ok. Grant
Jun 2, 2009 | Stencil Design I was hoping some-one would help you with this because I too would like more information about selecting stencil thickness. I have read some about apperature ratios, but this alone doesn't appear to be the only factor when chosing stencil thickness, ie. when you use a full apperature vs. a home -plate modified apperature. Can anyone recommend where to find more details on selecting stencil thickness? Thanks.
Oct 2, 2008 | Hello Ok there is not much info here. What you have to mae sure of is several key factors. 1. Have you entered the correct stencil thickness. 2. Are you using the stencil gerber (not the paste layer) The paste layer is usually not adjusted for appeture adjustment. 3. Does the machine you are using have zero offset adjustment in the programing and are you using it. 4. the last is what is the appeture ratio. This is the wall hieght to the appeture area. If you are doing very small appetures on a thick stencil the paste release can be very low due to higher surface tension on the stencil than the board. Jerry
Jun 18, 2007 | Agreed.
Mar 29, 2007 | Invar Stencils OK, just finished our prototype build. PWB 7.5" x 10" 16 layers smallest pitch 17mil smallest BGA pitch 30mil (round apertures) smallest component 0402 total of 1492 placements 5 mil stencil foil (invar) Had numerous PQFN packages that always gave us a little problem in the past. ZERO print defects ZERO solder defects after reflow I WILL be purchasing more Invar stencils!! NOTE: Stencil vendor states the Invar foil will be fine to 15 mil pitch and 0402.
Mar 6, 2007 | Maybe swimming..
Mar 6, 2007 | Hi, What is wimming ?
Feb 16, 2007 | SRM is way off.
Feb 16, 2007 | What-ever! (gag!)
Dec 19, 2006 | Oh sh*t, we have the same "problem". But it's not really a problem. Depending on how thick your stencil is, and at what speed you run your squeegee blades at, you will get this deflection of the stencil. Age of the stencil is also a factor. You can minimize this by lowering you squeegee pressure, but again, depending on how thin/thick your stencil is it may never go away. Now when your operator gets naked and goes streaking at the screen printer - that's a problem.
Sep 18, 2006 | Speaking of tools... | V
Aug 14, 2006 | Exactly !
Mar 2, 2006 | NC or WS?
Feb 23, 2006 | stepped stencils Not sure on stepped stencil designs, very application specific. Try consulting with your stencil supplier. Most of the big suppliers have applications engineering support. You can send them your board data and they can review and advise. Also, consider solder preforms on tape and reel as an alternative to stepped stencils. Pick and place and solder preform where you need more solder. http://www.indium.com/products/circuitboardassembly/solderpreforms.php
Dec 14, 2005 | Fine Pitch Stencil Design Also we have just made a prototype for Wave soldered SMT components D-packs + 0603 + TSSOP�s on the bottom side with THT comp. on the top, the stencil manufacturer gave his personal library of glue stencil openings and adviced on stencil thickness which was over 0.2 mm thick which was new for us
Nov 2, 2005 | Hello, Thank you for answer. We are using second hand machine. What do you mean saying that �stencil is not height on all 4 corners�? Does it have some inclination between corners? I mean that three corners of stencil are matching with PCB fine and one has some distance between PCB and stencil ? Yes, we tried to use wet wipe, but solvent distributes non-uniformly along paper surface, hence wiper is inefficient at all and doesn�t wipes properly. Dry wipe gives no any effect at all especially on fine-pitch components. Stencil just remains dirty after wiping. BR, Pavel
Oct 31, 2005 | Hello Did you just buy this machine on the used market? There is a possibility that the stencil is not height on all 4 corners ( from the center nest assembly. I don't under stand " the under stencil wiper is not working correctly". This is about the only assembly on the MPM's that almost never fails to work properly. Are you trying to use the wet wipe? If so this can cause the problem that you have. I would try this, turn the stencil and board 180 degrees, then reteach the board. This will tell you if the machine has a problem with the board and stencil not mating correctly.
Oct 27, 2005 | How do you number your stencils ? We just bought a new/used ultrasonic stencil cleaner. The solvent we use is Zestron Vigon SC200. We currently number our stencil frames with sharpies. The Zestron eats the sharpie markings off. I have also tried acrylic paint markers.....eats the paint markers off just as fast. Stamping or etching numbers into our frames is not a option. Frameless stencils are not an option. I need some type of marker that withstands the Zestron, but can be removed with some type of a more aggresive solvent. Any ideas ?
Jul 14, 2005 | Possible to water wash no-clean solder paste boards? Our facility helps customers clean no-clean soldered boards on a regular basis, and it definitely can be done but is a little more challenging than boards built with water soluble flux - one piece of advice I would give is to use low water pressure (DI water preferably), but high flood in your cleaning protocol. Also - you may want to use a saponifier - Envirosense Envirogold is very good, and Kyzen manufactures some good chemistries as well. If you would like to read some case studies on cleaning a no-clean board, here is a link to my company's list of articles and case studies:
Jun 22, 2005 | Anytime......hahhahahahahaha..
Jun 22, 2005 | Stencil fiducials Thanks for your help. I have resorted to using pads as the PCB doesn't have fids particularly close to the stencils fids. All previous jobs have had fids in the same place on the stencil as the PCB. The printer has a wiper paper which I have set to every 3 prints... see how it goes. It is harder to find the same pad on the stencil as the PCB as they don't have circuit refs next to them!!, so thanks for the sarcastic comments "??"
Jun 3, 2005 | SMT Stencil Aperatures Hello, I was wondering about specs on SMT stencil ordering. I am looking to make some sort of template for aperature layout of some parts. I was wondering some issues that you have all came across or made to change to better suit your boards. For instance: 200ml or larger dpaks with window paned etched pad, 25ml with a 6mil stencil, etc, etc. I just would like to see what some standards are that you all go by. Or is it basically a hit and miss type thing when ordering a stencil for a new design? Any input would be helpful. Thanks
Feb 22, 2005 | Zestron.
Feb 9, 2005 | can anyone provide me with information on the operation of the Zevatech Print-MAT 220? Its a pretty basic machine, but my question relates directly to the squeegee blade setup and leveling the blades to the stencil. If you level the blades together to the stencil, then the rear blade does not meet the stencil when the head is flipped, and if you level the rear blade to the stencil, then I am concerned about the squeegee pressure on the front blade. All of my experience is with MPM AP & Speedline and newer MPM models, so I am spoild rotten with manual leveling systems. Thanks in advance
Jan 20, 2005 | no-clean flux removal manufacture cleaning systems so naturally I would like to see everyone clean their boards, but the facts are that not every application requires cleaning. In many cases the amount of residue left on the board is acceptable for that specific application. The cleaning industry does the electronics community a disservice if we suggest that all boards require cleaning. The flux industry does a disservice by suggesting that a particular flux leaves NO residue. Mike Konrad Aqueous Technologies (909) 944-7771 ext 29 www.aqueoustech.com
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