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Sep 6, 2018 | Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? I'm no expert but I think you will find the majority of discussions around BGA & good printing results focus on the PCB design and things like tented vias and pad definition. e.g https://macrofab.com/blog/bga-pad-creation-smd-nsmd/ After that, work with your stencil supplier to create a stencil that works best for your design who might suggest stepping, coatings aperture reductions etc.
Aug 29, 2018 | It is recommended that the thickness of the stencil of 0.1mm, the steel mesh should be partially nano-coated. It is best not to dry easily, and the particles are not easy to be too large. I have tried ALLPCB for this kind of BGA in the past and they have done a great job Stencil and paste used for .4mm pitch csp component ball size .3mm?
Nov 15, 2017 | IMO – Look into nano-coatings for your stencil and radius all square apertures This should help out with solder paste releasing from the stencil helping with insufficient solder QFN LGA aperture design, try a stencil cut with a few different aperture designs to test. I have had success
Sep 22, 2017 | Just for the sake of passing along the information, the fine grained stencil provided zero improvement over the standard PhD stainless and was not nearly as helpful as the baked-on nano-coating. We probably won't be trying that again unless we go under .5mm pitch and also plan to coat it.
Sep 19, 2017 | that was that we got a little too much paste in another location (if we had auto SPI I suspect we'd be seeing better than 100% TE) but we think we've solved that problem with a reduction in blade pressure. The next step will be to try a finer grained stencil w/o the coating to see if we can get around adding a adjustments (all of the basics) were going to have any measurable affect. The most effective thing we did with what we had to begin with was optimize the setup with a little better support placement, but ultimately it was a nano-coating that got us over the hump. The only negative effect in using day to stencil lead time and concerning ourselves with stencil washer detergent concentration more than we'd like to.
Sep 19, 2017 | the recommendations. 4. Nano coatings. If you need them, then you need them. You should at a minimum be using quality stencil squeegee blades that are coated. This is such an easy thing to do, and it makes a small difference. Sometimes a small difference is all you need to make an iffy print into a good print. I Steve, The 4 things I would do, and in this order: 1. Clean your stencil with stencil cleaner wipes after it comes out of the stencil cleaner. I like MicroCare ProClean (MCC-PROWR). I will even saturate the wipe with a bit of isopropal just till the wipe is damp, at least on the 1st pass. I wipe the bottom vigorously for 20-30 swipes forcing the solvent up through the apertures, then wipe the top once from left to right. If the wipe has any "dark" material at all on it i repeat the process till it does not. The stencil must be absolutely clean for these types of parts. Trusting in your
Sep 7, 2017 | Two magic bullets help us greatly with fine pitch printing: 1) nano coatings (we use a DEK product) YES it really does work 2) temperature control in the printer (AC unit). Of course good quality stencil and proper cleaning of the stencil are important, too. You might consider having a set time-frame where you pull the stencil and clean it.
Sep 7, 2017 | HI Tsvetan, Can you tell me what material your stencil was fabbed from? I have seen (from different suppliers) references to at least 3 different grain sizes of stainless for laser cut, plus electroformed nickel for laser cut, electroformed nickel, nano coatings, etc.. I'm trying to determine if the advanced materials and coatings are the right solution if all other design parameters are exhausted, or if we have another issue. Thanks!
Sep 7, 2017 | Chrys Shea has published extensively on stencil materials, coatings and paste release mechanisms. Many of the papers are available to download on her website. Just search for Shea Engineering Services. I've worked with Chrys in the past, she is definitely an expert worth consulting.
Sep 7, 2017 | In my experience with similar sized parts, the nano coatings (or what ever your supplier might call them) do help with repeatable paste release. How are you cleaning your stencils? A big red flag to me is that your stencil worked fine for the first run, but had issues on the next. If the apertures
Sep 6, 2017 | mil). At one point during testing we ran 31 straight panels (10 uBGA/panel) without a paste release issue. This is stainless steel stencil of standard grain size material with no coating or other secondary treatment. We started running it again this week and had more problems. Moved the stencil to a Hi All, We are being intermittently challenged by a .5mm pitch uBGA paste release issue. We don't build with many of these so don't have a lot of history here. We've gone through 3 different stencil designs and the most consistent performer was 4 mil thick with round 12 mil apertures (pads are 11 different line and performance improved but is not what I would call acceptable. The defects are randomly distributed on the panel. My question is, how many of you bit the bullet and went with more expensive, finer grained materials to solve this problem, how many are having a coating applied by your
Jun 14, 2017 | IPA versus Stencil Cleaning Solution Nitrating is new to me too. I assume it means nitride coating.
Jun 14, 2017 | IPA versus Stencil Cleaning Solution In my experience there is no need for wet wiping stencils. We run 0201'and micro BGA's daily with no issues. If you are having paste release issues, I would be looking at other things. Aperture area aspect ratio, aperture design, land design, solder paste...to name a few. I'm personally not a believer in "nitrating" or nano-coatings.
Jan 31, 2017 | If there is no specific quality reason, stay with paste. More processes you add, more points of failure. They don't need a lot of paste to get attached to the board. The ones I used were 8mil round apertures, so I did cut 1:1 on a 3 mil coated stencil and it worked perfect. For repair you can use
Oct 8, 2016 | Conformal coating rework jumpers A friend in the contract coating business said: "... ask why the wire is [teflon] coated in the first place, as only the solder joints should be coated in this situation as the flexing/bending of the wires will cause the coating to crack and flake off of the wires. If this were a board that we would be coating, I would only coat the solder joints here."
May 26, 2016 | Conformal Coat Yes - the frame is built to nominal per print then the tape pieces are placed into areas in the frame as required. I had the stencil house cut #'s into the frames designating each different size. When I cut the tape pieces, I put them on a large, smooth piece of G10 or FR4 then numbered each
May 26, 2016 | due to the complexity. Too leaky, too much maintenance so masking tape is only option as we don't have a fancy programmable conformal coat machine. So, I designed frames and had them cut by stencil house. Frames sit on assy, aligned by tooling holes; they outline all specific masking tape locations Conformal Coat Not exactly SMT but something I recently did that might save you lots of time and money: Complex high $ assy that has 25+ conformal coat keep out areas - most different shapes. All locations are dimensioned on customers' print. We tried a one piece masking fixture but it just didn't work well
Jan 29, 2015 | I agree with SWAG on this. Nano Coatings make a big difference on paste release. I found when placed on the topside of the stencil, it also helps to reduce stencil wear, though others complained that it affected the solder roll, so most stencil houses now apply it to the bottom side. (I didn't have
Dec 1, 2014 | Yes nano coating giving the good printing, but the stencil tension is very important for the life, 1st ensure the stencil tension... stencil
Nov 21, 2014 | Use nano-coating and your stencil will last a-hunnit-fiddy-million cycles. Yessur.... In reality I cant say that I have ever seen a worn out stencil. Damaged and dinged, but never worn out. stencil
Nov 21, 2013 | Tin Lead Electrodeposited Plating and Conformal Coat Generally, solder connections and leads are conformal coated, unless there is a reason not to coat them.
Oct 18, 2013 | Hege, the Nano coating goes on the opposite of the squeegee side of the stencil. I don't know if the cleaning paper is able to remove it little by little with the time, but I never refreshed my stencils with Nano coating and they work just fine. However I don't run big quantity products...
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
Aug 30, 2013 | coating uv light inspection Contact the coating manufacturer to get their response. We use many different coatings every day and they all glow differently but that has no affect on the coating itself. As stated earlier, it's job is only as an inspection tool to identify where coating is or is not. It has very little bearing
Aug 20, 2013 | I believe that Rain-X contains silicone and Nano-ProTek solution does not. I did speak with a field service guy for Nano-Protek and he told me the special coating test pen that they offer is just a sharpie with their logo on it. Thats how I test to see if my stencil coatings are still there and it has worked so far. Also, in my experience, and his, alcohol does not remove the coating. As that was my initial reason for calling. I have only noted a significant improvement to a coated stencil with some fine pitch apertures on thinner stencils (4mil) when we were experiencing insufficient solder Nano coatings ? PAPERS!!! ... We want papers!
May 2, 2013 | Acrylic comformal coat on PCB we have a Specialty coating system (SCS) precisoncoat spray coating system. we are using an acrylic coating material with about 80cp viscosity. The spraying pressure is around 4-6 psi. The main issue is the finish looking of the board. If we apply high spraying pressure, the coating surface on the board would be roughness (not uniform or smooth). This may be caused by the high spraying pressure. if we drop down the pressure and increase the coating flowrate, the coating thickness on the board is too large to qualify the IPC standard, but the coating surface is very smooth. Do you have any tips
Mar 18, 2013 | The paste is going to roll as before because you have to apply the coating on the bottom side of the stencil. Also the coating that wears out will most probably go to your stencil cleaning paper as that the process wehn you actually have friction with this layer. Nano coatings ? PAPERS!!! ... We want papers!
Mar 18, 2013 | chemically bonded processes use a colored dye so you can see when the coating begins to fail. Claims of 80K + prints were made. Another point: your solder paste roll potentially no longer "rolls"...it skids across the stencil because of the lack of friction. My guess is that you won't be hearing about Nano coatings ? PAPERS!!! ... We want papers! I was at an SMTA meeting Friday. One of the topics of discussion was nano coatings. 1. Nobody wants to talk about where the coating goes as it wears off. 2. There are different types of nano coatings : Chemically bonded which involves a special bonding process and manually applied.(wipes) Some
Mar 5, 2013 | Here is "Compatibility Of Cleaning Agents With Nano-Coated Stencils" David Lober and Mike Bixenman, D.B.A., Kyzen Corporation: http://digital.trafalgarmedia.com/issue/46004/25 Nano coatings ? PAPERS!!! ... We want papers!
Feb 25, 2013 | Oded: The coatings that I mention serve different purposes. * Antiadhesions seem to be designed to improve paste release from the stencil * Flux repellents seem to be aimed at reducing the under wipe frequency of stencils. At IPC APEX 2013, DEK and Aculon presented papers: * Big Ideas of Sales & Marketing 770-807-4707 eric.moenatlaserjob.com My contact at FCTA is: Jeremy Glanzer, Marketing, 970-214-4854 jglanzeratfctassembly.com I believe that Kyzen wrote a white paper on cleaning coated stencils. BR, davef Nano coatings ?
Feb 22, 2013 | Nano coatings ? I don't know, what you have, but I just got back from the IPC APEX show and I'll make several points: * One take away about 'nano ...' is that it means different things to different people. For instance, in stencil printing: ** DEK uses Aculon and it is a flux repellent ** LaserJob uses Siemens
Feb 22, 2013 | I have been told that stencil nano-coatings are rain-x in a different container. I guess I half believed it until I opened up a sample the other day. It smells EXCACTLY like rain-x. For those of you that have never smelled rain-x it has a very distinct odor. It's not easily confused with something Nano coatings ?
May 17, 2012 | I don't have an opinion on nano coatings since I haven't tried them. Our suppliers keep pushing it so I'll eventually check it out. The reason I zeroed in on the FG foil is because I almost fell into that trap. Several years ago I wasn't aware the suppliers were replacing their YAG lasers with fiber, so I would buy one laser cut stencil that performed about the way I was used to then the next from the same supplier would perform as well as an electroform. I couldn't figure out why. Then I bought an FG stencil based on the hype and was impressed with how it performed. What I didn't realize was that the laser type and foil type were confounded - since the FG foils only came fiber cut I didn't know whether its performance was due to the FG material, the laser type, or a combination of the two. With later stencil orders I was able to separate out the effects and see that the FG foil wasn't what gave
May 11, 2012 | acceptable level. Nano protek can be re-applied and will not adhere to itself so it only depsosits to those areas that require it. I am only familiar with Protek and coatings from Laserjob in Germany and a Japanese company. There is a material called FG coated with Nano Protek and must be cut on a fiber Diode laser. This is the most sought after stencil today. Although I am seeing an interest again in Eforms.
Aug 29, 2011 | Conformal Coating Discoloration Greetings...I have a customer that has an assembly that is conformal coated with Humiseal 1A33. This assembly has some components (resistors and FET's) that heated up during operation and has discolored the conformal coating around their location. (Turned the conformal coating a brownish color ). Per IPC-A-610, discoloration of conformal coating is a Defect Class 1,2,3. However, this discoloration is NOT a result of the conformal coating process or the conformal coating itself but rather from the heat given off by the components on the board. Does this discoloration pose a reliability
Jul 22, 2011 | chemically bound to stencil. Also they say Nano Pro Tek coating is less than 5 nanometers thick whereas I think Rain-X is at least 50 -100 nanometers which will clog some apertures. I know Rain-X is cheap but we would not bring that into our facility. Nano ProTek Coating I would be careful with trying Rain-X. Rain-X is a silanol treatment that is not durable. That is why you need to reapply it on a windshield many times. Also you could contaminate the paste as it will come off the stencil during the printing. From what I know of Nano ProTek it is permanently
Jul 22, 2011 | It's actually a "silane" according to the same article. Also, it "bonds" with the surface of the stencil. once bonded, it's not going anywhere. I'm not a chemist. I'm not promoting this product to be used on stencil. I'm just pointing out that what is sold as Nano coating for $300/10 pak may just Nano ProTek Coating
Jul 22, 2011 | Rain X goes on windshields. Nano coating goes in the garbage. Order your stencils correctly from a reputable stencil house and fugetaboutit. Nano ProTek Coating
Jul 21, 2011 | Nano ProTek Coating Using AIM N.C. paste, just ran 10 panels to test after applying Rain-X to the stencil (pre-clean with IPA). Printing and release were slightly better (maybe my imagination), but not a large difference. Stencil remained cleaner longer. I could not tell the difference in finished product, but did not x-ray or chem analysis. I plan on continuing test with increasingly more critical stencils. The previous test was with a very simple/easy job, just in case...
Jul 21, 2011 | Nano ProTek Coating So far after ~1500 units printed with the stencil treated once with Rain-X, no issues were detected with solder joints. The only difference is no more solder bridges on fine pitch with .010" openings. The print is picture perfect on all pads, nice and even, flat across the top.
Jul 21, 2011 | Nano ProTek Coating I cleaned the stencil with IPA 99% before applying the Rain-X. Apply Rain-X as per instruction.
Jul 20, 2011 | Nano ProTek Coating I have tried it, and it does what it claims. Don't know about durability yet, tested it on a short run. Cost: $300 for a 10pak (10 stencils) Tested a different stencil with Rain-X applied to it, so far same result, the paste does not clog the fine apertures where we used to have problems. We wipe the stencil underside every 10 PCBs now, compared to every 2 before. Been running >200 PCB over 3 shifts now on Rain-X. No signs of contamination from the stuff. Yes, Rain-X, the stuff you buy at auto shop to treat the windshield so that the rain just rolls off the glass. Cost: ~$6 for 200ml, enough for ~100
Jul 20, 2011 | I think you are referring to nano coatings. Try google nano coated stencils solder paste release from stencil
Jul 8, 2011 | coat the entire stencil. This has enabled me to reduce squeegee pressure slightly. It does seem to work in my application. I'm just curious what others have noted. Nano ProTek Coating It's a $40 adder to my stencils if I have them apply it. But I've just discovered that if you have THEM add it, they add it thru a stencil and only apply it to the appertures. (My guess is they do this because it allows them to use much less material and therefore save $$) If YOU add it you can
Jun 17, 2011 | Has anybody else tried using stencils coated with Nano ProTek? I did find that I could reduce my cleaning frequency and squeegee pressure, which should help to increase stencil life, but I'm finding that it seems to wear off quicker than I thought it would. I'm still evaluating the value. Anybody Nano ProTek Coating
Sep 14, 2010 | Hi Gani, HASL is normally very good for solderability providing there is a good consistent coating of HASL on the pcb pad. But it is not unusual to have a very thin coating of HASL on the pad and this is poor for solderability. You then have tin/copper intermetallic on the pad and this is much more difficult to solder to. Immersion silver is better then this tin/copper intermetallic. Your aperture pad ratio is 1:1, but are you absolutely sure you got a good paste deposit on this pad ? What is the aperture diameter and stencil thickness ? Have you compared its cross section to a nearby good BGA joint
Sep 14, 2010 | Hi Sir grahamcooper22, There should not a issue in stencil since i had open the aperature 1:1(one to one).Futhemore this is HASL pcb coating as now our customer had convert to immersion silver.I had do comparison between both and found HASL wetting not so good as immersion.May this one of the root
Sep 14, 2010 | Hi Gani, Looking at the pictures in the report it looks as if there is a thin coating of solder on the pcb pad....but it looks like the BGA sphere was barely in contact with the pad. This could be caused by insufficient solder paste on this pad...maybe the stencil aperture was blocked
Aug 23, 2010 | Possible route causes of bridging on fine pitch ICs are; too much paste (stencil aperture wrong), poor print quality (paste smudges during printing), pcb pads not flat depending on the solderable coating, paste has poor cold slump properties, too much component placement pressure smudges pastes , wrong reflow profile makes paste hot slump / paste has poor hot slump properties. To help further we need to know... What is the pcb pad coating ? What is IC pitch and pad size? What stencil thickness / aperture size are you using ?
Sep 30, 2009 | BGA failure after coating What type of conformal coating are you using and are you allowing the coating to migrate under the device in question? If you are allowing the coating unbder the BGA the problem could be CTE of coating is much greater than that of the BGA balls/solder joints. This can result in the BGA joints being fractured as the coating material expands under the device when it heats up in operation. Just a thought....
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