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May 20, 2019 | Step-up stencil: recommendation thickness Resources are: * IPC-7525A - Stencil Design Guidelines, 3.5.2 Step-Up Stencil This type stencil is useful when it is desirable to print thicker solder paste in a small portion of the stencil. An example would be a ceramic BGA where it is necessary to get 0.2 mm [7.9 mil] paste height because of ball coplanarity but 0.15 mm [5.9 mil] height on all other surface-mount component lands. In this case the stencil foil is stepped up from 0.15 mm [5.9 mil] to 0.2 mm [7.9 mil] in the area of the ceramic BGA. Another example is a through-hole edge connector that requires additional solder paste volume
Jan 30, 2018 | Has anyone heard of a no clean paste that can be cleaned in straight DI water ? This is one of the most common questions I get asked. Why clean no-clean flux. It was stated earlier that no-clean residues are benign. This may or may not be accurate. It depends on several factors including the reflow process. In a perfect world, the low-level flux residues are benign. In a less -than-perfect world, they may not be. There may be un-encapaulated flux activators or other ionic residues left behind if the reflow profile was not ideal for the specific flux type and volume. More importantly, when flux residues are not removed, nothing is removed. We should not consider cleaning assemblies a "de
Jan 30, 2018 | Has anyone heard of a no clean paste that can be cleaned in straight DI water ? I believe the correct statement (I've been told) is "the process is no clean". The solder paste is "low residue". As a CM, in the past we had customers that insisted on a wash after soldering. We used DI water with a saponifier which had mixed results. Sometimes you can't convince someone that the low residue flux remnants are benign and do not affect the long term reliability of the product, they still want shiny and clean. If we could go back to the TRI 1,1,1 and liquid Freon cleaning era.....that would be great, oh except for that environmental thing.
Nov 7, 2017 | If no-clean flux is reflowed correctly, many of the activators are encapsulated within the resin residue left behind after reflow. An ionic contamination test cannot differentiate between ionic residue that was encapsulated (not harmful) and residues that were not encapsulated (harmful). Keep in mind however, when no-clean flux is used and in cases when no-clean flux is actually not cleaned (today more than 50% of no-clean is cleaned), nothing is removed from the assembly. When assemblies are cleaned, it's not just flux that's removed. All process residues are removed (board and component
Nov 3, 2017 | Testing effect of non-clean flux residue on solder joints IPA and DI water are both very common and effective methods of cleaning PCBAs. http://www.zestron.com/sa/cleaning-applications/smt-electronic-cleaning/pcba-cleaning/aqueous-cleaning long time. For cleaning the board is immersed for a few minutes, then allowed to dry. This level of exposure isn't enough to harm the PCB. IPA is a common house hold chemical used in numerous products. Rubbing Alcohol is just IPA with an extra chemical mixed in it to discourage human consumption (at
Mar 20, 2017 | Testing effect of non-clean flux residue on solder joints We're currently using no-clean flux (SR-12) in a no-clean manual soldering process. The brownish flux residue impedes direct visual inspection of the solder joints. Therefore, we're forced to clean the residue off. (1) Is there testing we can do (environmental stress chambers) with which we can see the long-term effects of flux residue on solder joints? (2) Has anyone else seen this problem with no-clean flux residue and how do you handle it?
Mar 16, 2017 | Tools For Cleaning PCB after Soldering Hi! I have a very basic question about PCB cleaning. Which is the best way to clean the PCB after soldering? We use a lead free solder wire (3,5% flux inside the core) and after the soldering its a visible wetting,flux around the joint. When using the Flux remover the surface gets clean but it leaves sticky on it (when touch with fingers). Same things occurs when cleaning with IPA.
Dec 8, 2016 | Batch cleaner not getting PCBs clean and dry We have a name brand aqueous batch cleaner that uses a chemical and DI water to clean ROL0 flux from our PCBs. It does ok most of the time for SMT boards and we want to include through hole assemblies as well which should be a better cleaning process than our IPA cleaner. The problem is that PCBs with through hole parts (especially connectors and toroid inductors) frequently do not clean entirely and come out not fully dry. I understand that shadowing and crevices can be a significant factor. I want to know if others are having challenges cleaning through hole PCBs in a batch cleaner and what can
Sep 1, 2016 | Is there any field proven spray cleaning technique able to remove flux residues under OSRAM LEDs? Is it possible in principle? The problem is that OSRAM LEDs are low standoff ones and I absolutely have no idea how cleaning agent could get there. More process details: Cleaning machine - spray (clean, rinse, dry) Cleaning agent - Vigon A250 Paste used - KOKI S3X58-A230 OSRAM partnumer - LRTB GRTG Any input would be really appreciated. Regards, Pavel
Oct 18, 2013 | You might try testing prior to using the Silicone if possible. Also you might try to qualify your cleaning process rather than the individual board. Clean an unrelated assembly and test it in your Ionagraph. Assuming it passes, Clean your subject assembly, but do not test. Then clean another unrelated assembly and test it. If it passes you could reasonable say that your cleaning process removes ionic contamination, and that the subject board would be free from contaminates. I don't know, however, whether silicone in its cured form can emit or present ionic contamination in and or itself. Just
Nov 13, 2009 | Stencil Printer? -shell printer for years. Not any framed stencil will just drop in place. I had a few very old 12x12 framed stencils that I had to build an adapter to use. All models of 12x17 cast Aluminum frames from Fineline Stencils (FCT) have fit well though. LPKF provides a Gerber file for the stencil mfg so that your stencil can be built to fit their removable frame.
Sep 30, 2008 | No clean and 100 Mbps Fast Ethernet Transceiver Residues from different no-clean fluxes produce different levels of variation in RF circuits. Some no-clean fluxes work fine. Following this, a no-clean flux can produce different levels of variation in RF circuits depending on the process setup. Often the data sheets for solder paste with no-clean flux aimed at RF applications say, "This material has been utilized on various assemblies with RF designs without cleaning; however, the compatibility of flux residues on RF assemblies is strongly dependent upon circuitry design." The tech sheet from your AIM NC254 No-clean solder paste gives
Sep 8, 2008 | Clean vs No-Clean Here are links to articles on that subject:
Can You Clean a No-Clean Assembly?
Component Cleanliness in a No-Clean World:
May 4, 2008 | Hi all,
I recently acquired a year 2000 dek 265 horizon. It has a manual screen loader with that stupid hand crank adjustable stopper. Can anyone tell me how I am supposed to measure the stencil image dimensions for a front justified stencil? Now on a 2007 Horizon 02i the distance to a front justified stencil image is measured from the rear of a 737mm stencil to the front edge of the image. This number is then transferred over to the adjustable stopper. This number does not match with any setpoints on the 265 Horizon. I am told that the numbers on the handcrank stopper on the 265 horizon are for center justified stencils only. This is true, but there has to be a formula to be able to use front justified double image stencils. Please help! Thanks.
May 4, 2008 | Hi all, I recently acquired a year 2000 dek 265 horizon. It has a manual screen loader with that stupid hand crank adjustable stopper. Can anyone tell me how I am supposed to measure the stencil image dimensions for a front justified stencil? Now on a 2007 Horizon 02i the distance to a front justified stencil image is measured from the rear of a 737mm stencil to the front edge of the image. This number is then transferred over to the adjustable stopper. This number does not match with any setpoints on the 265 Horizon. I am told that the numbers on the handcrank stopper on the 265 horizon are for center justified stencils only. This is true, but there has to be a formula to be able to use front justified double image stencils. Please help! Thanks.
Feb 15, 2008 | Inspecting a new stencil FYI, Here are the steps in which we take to get approval. The stencil gerber layer needs final approval through our Engineering dept. What they do is send in a gerber layer from the stencil house and lays it over the current solder paste layer and verifies it will match within thier gerber viewer . Once that is proven than the stencil house can manufacturer the stencil and send out. Now as for when it gets into house we dont open the package almost until the job gets ready to run down the line. We have had maybe a handful of stencils in past 5 years that maybe had an issue and we had to due next
Dec 19, 2007 | Stencil Printing: Single pass vs. Double pass "Any risks associated with double pass stencil printing?" Mostly just too much paste, plus the associated bridging, and your stencil gets dirty quickly. Any gap between the stencil and the board gets filled with paste on the first pass, then migrates laterally during the second pass. In my experience the only reason you should "need" to do it is that something else is wrong with your process, like a bum printer, old paste, worn out stencil, etc. You can probably get away with it for a .050" product, but not with fine pitch unless everything else is in your favor (your stencil is in really good
May 30, 2007 | Small Batch PCBA Cleaning I'm trying to find a solution that will clean our PCBAs that will meet the following criteria: 1. Low cost 2. Enable us to clean 25 - 100 PCBAs per day 3. Leave boards clean, including residue removal 4. Preferably environmental friendly 5. should be able to handle PCBs ~12" max edge width We use RMA flux right now (SN63PB37, rosin core). We've tried cleaning by hand with Vigon EFM and / or RC101. EFM left lots of thin residue on the assembly. RC101 couldn't clean off thick flux deposits. I tried a dual process and the results were better, but I had to spend way to much time cleaning
Mar 29, 2007 | To use a mini stencil, or not to use a mini stencil. Ewwww metal mini stencils? Try http://www.circuitmedic.com/products/stencils.shtml We use their flextac stencils all the time and they work perfect. You can get a couple uses out of each of them if youre
Mar 2, 2007 | Stencil design Hello, I havea 0.4mm pitch TQFP with heat transfer pad on the bottom side of component. I will appreciate any suggestions with regards to: 1) stencil thickness (Rest of components on board are 0603 passives and few 40 mil pitch IC's) 2) Stencil aperture openings for the heat pad under the QFP
Feb 15, 2007 | Stencil Fiducials We have five 1997 DEK 265LTs, and we have never had to have the stencil house blacken any fiducials. The fiducials are etched about halfway through the stencil. You can adjust the lighting in each individual program, not just a global lighting change. We did not get them from superman, the green
Feb 15, 2007 | Stencil Fiducials Does Ekra or MPM require stencil fiducials be filled with Black Max or some other black epoxy? We still require our stencil supplier to do this. I did not have to do this on any Dek solder printers since 1997. Can the MPM UP2000 HiE fiducial lighting be adjusted? I know if you hit "next
Feb 9, 2007 | If the attack was unwarranted I apologize. I still stick to my answer. Unless the board shop can get rid of it you have to find a way to deal with it. Etching trace paths into the stencils is inexpensive and works just fine. If you do not have the time to design a stencil... try to make the board house design one... or at least create a common gerber layer, containing pads and affected traces, to create a stencil from.
Aug 23, 2006 | Nope, and, Be careful with the "grid" on your stencil for the big centre pad - I could not find the stencil recommendations. I use a similar part by Cygnal (CP2101). Next time I will reduce the apertures by 50% from their suggested layout. We had floating and bridging issues with a 0.005" stencil
Aug 2, 2006 | Can UP 2000 printer work with R and L justified stencils? I mean if you are using the same stencil for the top and bottom of a board. Thanks to everyone for the help. From what I gather, it will work when the stencil cut-outs are offset from center in the Y-axis. Doesn't work too good in the x-axis, because the machines x-axis range of travel is only a
Jul 31, 2006 | Can UP 2000 printer work with R and L justified stencils? You should be able to do it in > TOOLING > OFFSET. The pcb stopper is attached to the camera and a default stop position is calculated from the PCB dimensions. If your stencil image is offset left or right then you can either fiddle the pcb size or input the offset. Offsets front and back can be much more difficult. If the image is too far from the centre to the back then you may have to move the stencil so that it is partially hanging out of the machine - you may have to bybass interlocks etc. If it is too far offset to the front and you can't physically move the stencil far enough
Dec 14, 2005 | Fine Pitch Stencil Design Yup, I saw the original question too. I just can't see how any one would let a stencil manufacturer dictate their processes. Maybe if your designs are small and straight forward, but are you really going to let a stencil maker tell you what products will be either double sided reflow or wave
Dec 14, 2005 | Fine Pitch Stencil Design the original question was: Please give me some guidelines on designing Stencils for Fine Pitch. which i did however, 40% fallout for solder shorts this could be caused by many other processes having gone wrong before, i.e. type of solder paste and oven temperature profiles, stencils would be the latter of these things that i would check for faults,,,, or maybe i am just lucky and have a great stencil manufacturer who checks my stencils for problems, how ever small they maybe.... latest problem i have had was heat sync under SMT comp. and too much solder paste resulting in tin balls and weak
Dec 8, 2005 | Fine Pitch Stencil Design Hi, How fine pitch are you going? What kind of stencil printer are you using? We had a manual stencil printer and needed to print 1-mm pitch BGA and needed to go to laster cut and electro polish at 4 thou to get good paste release. We also went 1:1 reduction. However with the DEK being a much better printer, we went back to 5 thou, and don't have problems. Stencil design is really the most important part of your process, apart from perhaps the oven temps. But a bad print will cause most problems. If you have more info on what kind of parts your placing, it might help some suggestions
Oct 7, 2005 | Water Jet Stencil Cut Thanks everybody for your comments. I am not going to move to stencil waterjet cut. But because recently talk to people who want to move in that way, so that's why I am trying to get infos as much as it possible in order to learn what does it mean a practice like that to make mask & stencil cut
Sep 11, 2005 | If 0 or 180 degr. make v-shape openings to each other left & riht, if 90 or 270 degr. top/ bottom, on the stencil apertures; well, you understand... We use this and 87 % reduction of stencil apertures for 0603:s and 0402:s. 0.127 mm stencil thickness. We have no problem with tombstoning and solder
Sep 7, 2005 | The best solder paste height with screen priting on 6mil stencil I am engaged with SMT production and we are going to have a brand new SMT line and I am studing about the screen printing and I have seen most commonly used stencil thickness is 6mil and I need to know what is the best solder paste height we can achieve with this type of stencil with better
Jul 12, 2005 | Lead Free Stencil Design Hi, My stencil maker also say the same thing on 1:1 for lead free. I am using electro-form stencil. You can look for Mr Richard or Mr Chong at email@example.com. Hope this info will be useful for you
Jun 6, 2005 | SMT Stencil Aperatures Don't forget follow up is very important with stencils. Check with SMT after the first run with each new stencil and see how it went. If you follow industry accepted standards you probably won't have any problems but you never know when you will run into something that doesn't fit right. In theory
May 3, 2005 | I appreciate the detailed reply. However, I had tried dimensioning the stencil to everything imaginable, including the correct/measured dimensions. Interestingly enough, after loading a new stencil into our adaptor, I had no errors with the new program. The only difference between the two was the space between the PCB on the stencil - the new one was centered with 5" or so clearance on all sides, whereas the problematic one had just over 1.5" clearance - not enough room for the stencils to clear without coming down on the epoxy - another problem in and of itself. Since we're going to have to have those stencils re-cut (as we need to open addtl. fiducials) anyhow - in moving to a 29" stencil, I think our problem will be solved. Does that behavior make any sense, however? I can't understand why the PCB to frame edge dimension would interfere with loading/positioning correctly... Thanks a
Mar 23, 2005 | Stencil Organization/Storage We currently have about 800 active stencils. You Need a phase out program for your customers products. Otherwise you end up in stencil hell! Additionally, our smt team uses an access database to find what they need. Customer, assembly,revision, side = rack # and slot number.
Mar 16, 2005 | Try varying you conveyor speed as well to increase the dwell time on the wave (touchy, and can easily be overdone). Every no-clean type and process I have ever used will leave some type of residue. They can be minimized but they will always be there. I expect shortly that there will be a post about the "zero residue flux" that we have all asked about regarding the data supporting this. when this happens please use this flux and tell us what happened. I still get tweaky when I hear "we have to clean our no-clean by hand"! If your boards need to be spotless why don't you use a clean process ? you are defeating the purpose/advantage of no-clean when you clean. Also do you really think that you are cleaning the board or just thinning it out so you can't see it?
Jan 5, 2005 | Q1. Is it enough to use only water while cleaning or is it necessary to use any additional chemistries and/or saponifiers as well? A1. It depends on: * Flux residues that you're cleaning * Standoff of the components * Cleaning technology [we've never heard of 'supersonic cleaning']. Q2. Where should the used water be pour out to? In Datasheet for paste and flux there is no information concernig the matter. A2. It depends if the output of your post-cleaning water purification process is acceptable to your PTO. Consider: * IPC-AC-62A - Post-Solder Aqueous Cleaning Handbook * Your cleaning
Oct 26, 2004 | Stencil Tension Yes, we have an SOP on how to measure. Basically, calibrate the measuring device and measure tension on the 4 sides and one at the center of the stencil. All measurement should be within 30 ~ 50 N/cm otherwise we will not use it and return it to stencil fabricator to fix it for us. I need to check
Sep 14, 2004 | Labeling of SMT solder stencils Thanks everyone for all the input. All of our stencils do have the PCB # etched on the foil but when operators look for the stencils they are looking for the part # on the frame since they are all stored vertically in a couple of Remstar shuttles and a couple of movable racks and our database shows the locations and PCB status which helps quite a bit in knowing which stencils I can get rid of. I though about the stamping thing but since we cycle through frames so much I would have to grind off the old # when a new stencil came in. As far as getting out of this rathole, its not going to happen here. My
Jul 21, 2004 | flux on PCB's after cleaning problem: Too many solvents and boards are not clean Flux remains on the board after vapor degreaser and "Powdery" white residue after vapor degreasing Flux type is kester 186 Process: hand solder High Temp alloy, spot clean after hand solder equipment: Vapor degreaser and spray wash batch cleaner solvents used: proclean, Flux off-Rosin, BioACT EC-7R, vigon-A200, hydrochlorofluorcarbon (hcfc in vapor degreaser), Isopropyl alcohol Possible problems that could be contributing to the situation are: Mixing the flux off chemical with proclean [using both (one after the other) to spot clean
Apr 13, 2004 | Water Soluble for No Clean BGA Balls Hey Dreamy, Dave is correct. If you attempt to clean your water soluble (OA) flux with water only, you will turn the no-clean flux white. No inspector or end-user will accept this. If a proper cleaning system is not available to you, then I would recommend one of two things. 1. Utilize a contract cleaning service to properly clean your assemblies. We operate one (www.aqueoustech.com) and so does Austin America (www.aat-corp.com). 2. Buy cans of Micro-Care cleaning chemicals and manually pre-clean the no-clean flux thoroughly prior to using your dishwasher for OA flux. Soak
Apr 13, 2004 | I would have gone to a .004" stencil but again, the board designers, which we have no control over or are we allowed to give input to, have made the pads on all connectors and many other parts so small that we are almost seeing insuffecient solder using the .005" stencil. I have most all stencil
Apr 2, 2004 | clean process vs non clean process There is no shortage of reasons to clean your boards. Soldering or reflowing your boards leaves �stuff� on them. This �stuff� is normally corrosive and conductive (some fluxes / pastes are more corrosive / conductive than others). In either case, if you do not desire any residue on your boards , clean them. Military, medical, space, flight, and other boards all require specific levels of cleanliness. In most cases, these levels are only accomplished via cleaning. Some boards are good candidates for no-clean while others are not. While I am a strong proponent of cleaning, I have never heard
Mar 24, 2004 | No-Clean Wave Flux - Water Wash I recently did a no clean flux eval and by far the leader in the category for remainder (residue) was Interflux 2005MZ 1. You first mission is to provide acceptable solder joints. 2. Only apply what you need to achieve acceptable results. Spray fluxer is the only way to go. 3. Next, consume as much flux in the solder wave as possible. 4. Clean the (no-clean) assembly (post wave). The less on there to begin with, the less cleaning required. sidebar: I hate customers that want to clean no clean. Use water solouble flux for cripes sake!!! With a proper thermal profile and wave dwell time
Jan 29, 2004 | Rick, As I understand your comments, you do not need to clean off the flux residues? Then hot water and a little cleaning chemistry should do. However, there may be some reaction by the residual flux if not enough cleaning chemistry is used. There are many out there cleaning no-clean flux residues . Its best to use a chemistry such as supplied by Zestron, Kyzen and Petroferm. www.zestron.com www.kyzen.com www.petroferm.com Consult your solderpaste mfg. and the cleaning vendors for best chemistry match for your application. There are batch type and in-line cleaning equipment that can do the job on fine-pitch leaded and BGA components. I would not consider ultrasonics as it may damage some components such as ICs and clock types. When using chemistry you need to rinse with DI water after. You do not want any of the chemistry remaining on your assemblies after cleaning. Any machine you look
Jan 21, 2004 | Stencil Aperture Sizes Depending on how you frame the question, either of you could be correct. Neither of you mentioned stencil thickness, which together with aperture opening [and stencil fabrication technology] define how well a paste will release. So, the key measures are: * Aspect ratio * Area ratio Search
Apr 7, 2003 | Sorry, I forgot to include the stencil thickness. It is 5 mil. Thanks for the input, everbody. I just checked with our stencil supplier & I thought that Electro-polish was standard with lazer, but I now find out it is not. Our stencil did not get the electro-polish! So that could be part
Feb 26, 2003 | Stencil cleaner We use an alpha metal stencil cleaner and was curious to find out what types of solvents and cleaners were used out there. It takes about 350-400 litres of fluid. I would be interested if there is something water based we could use. What types of stencil cleaners are also being used around
Feb 5, 2003 | stencil design software I'm new to the smt game. I'm trying to learn the basics of stencil design. I've just been tasked with removing and replacing a couple of mictor connectors. I need to find/design stencils for the solder paste. These boards are proprietary, and we don't have the artwork. But AMP has provided
Jan 27, 2003 | White residue after cleaning with IPA Dave is correct. No-clean flux + water = white residue (unless the proper chemical is mixed with the water). Additionally, no-clean flux + IPA = white residue. Many saponifiers work well as do other cleaning agents. White residue may also be a result of profile issues (usually too hot). I do not understand why you are concerned about LED�s. LED�s are frequently cleaned using a water-based cleaning process. I can recommend specific cleaning chemicals but keep in mind that a chemical must be compatible with a specific cleaning machine. Here are some chemical recommendations. Please keep
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