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Feb 23, 2004 | Just to finish this up, We did manage to print this little part with good success without any major re-setup of printer settings I would not recommend these parameters for production to anybody however. You can print 2-3 boards before it starts to clog the stencil. Fortunately we only had
Feb 15, 2004 | i have always found any of the alcohol based solvents good.here in the uk we use the alpha make.wit
Jan 15, 2004 | Guys Does anyone have any design rules for a 121 pin BGA . The pitch is 0.031 thou, the ball diameter is 0.0115 thou . I would like to know the following : Pad and via sizes/type on the bareboard ? Stencil thickness and aperture size/sytle ? Solder paste particle size ? Any feedback would
Jan 12, 2004 | High temp balls (spheres for you PC types) They are non-eutectic balls. Do you have a reballer or stencil setup? If one device...may not be cost effective, but if many you can usually send back the the IC house for re-ball. There are only a handful of BGA foundries that do this work. Your IC
Jan 12, 2004 | , vacuum under stencil wipe, auto paste dispense for 45k? Thanks you
Jan 10, 2004 | hi grant, why you choose not mpm is clear for me not good support possibilities localy, dek mayb
Dec 15, 2003 | I would say the DEK printer I have had the best reliability with. I have used the MPM and had alot
Dec 10, 2003 | CHECK INTO WARRANTY AND SERVICE BEFORE MAKING THE DECISION ON PRINTERS. WE CURRENTLY HAVE A DEK ELA.
Dec 10, 2003 | I agree with all the comments saying MPM and DEK are OK, but more that spent those $90 KUSD in the m
Dec 3, 2003 | Hello As some one already said Dek and MPM printers are very good and reliable printers. I have be
Nov 5, 2003 | I just did a bga job with square aperture's, the reasoning is for enhanced print release and additional paste volume. Be careful of the edge to edge clearance between the stencil openings, I don't recommend going below a 8 mil clearance, you could be setting yourself up for a bridging problem
Oct 13, 2003 | Hi Andrea, Another good place to start in addition to the oven manufacturer is your solder paste vendor. They can help you select the correct paste and give you the right reflow profile to use for that paste. Keep in mind that most vendors (paste, stencils, ovens) will be willing to give you help
Sep 26, 2003 | Thank you Russ for the information. One more clarification- I found that the %metal content in lea
Sep 4, 2003 | I'm attempting to develop paste in hole process so that I can reflow a few plated through hole components on a mixed tech board. Tried various pastes, profiles and stencil thicknesses. Would appreciate any insights and/or pointers anyone can share on the process. Thank you.
Jul 2, 2003 | ???? What? I think I follow your logic. Bottom line is, using the same name, p.1 (that's p (dot) 1) over and over for every stencil you produce can lead to confusion both in our CAM dept as well as our vendors. Like calling every board you produce PN 123456 over and over and over again. Would any
Jun 17, 2003 | Consider searching the fine SMTnet Archives for discussion, for instance: Apr 9, 2003 | This just makes my head hurt.
Why do these 22 BGA with hundreds of solder connections each have "open circuit due to the lack of solder paste"? Something just doesn't sound Kosher. Tell us about:
* Stencil design
* Solder paste
* Board design in the vacinity of the BGA pads
* Board fabrication
Apr 9, 2003 | This just makes my head hurt. Why do these 22 BGA with hundreds of solder connections each have "open circuit due to the lack of solder paste"? Something just doesn't sound Kosher. Tell us about: * Stencil design * Solder paste * Board design in the vacinity of the BGA pads * Board fabrication
Mar 28, 2003 | Hi Have you noticed with 3D scan technology a flatter and more filled top with the Rheometric when printing the smallest of aperatures. The Applications guys from the 3D companies told me they did see flatter tops. Granted this has to come also with better stencils. YET I was wondering your
Mar 26, 2003 | Tell us more about your printer. squegge blade type ,speed, snap-off distance etc... You shouldn't h
Mar 10, 2003 | May I be the first to ask, how you plan on applying paste to the primary SMT? You won't be able to stencil it on as is typical. Do you have a paste dispenser? Also a lot of PTH parts can not take reflow temperatures, not even all SMT parts can. (been there done that, oops)
Mar 7, 2003 | with it, if you wish to remove the gold you will need to cover it with solder past and have no stencil reduction.
Feb 11, 2003 | manufacturing process change to use different stencil thickness. ... More Paste, ... More Waste!
Jan 29, 2003 | Hello!! I need to know the land pattern specs for a melf resistor with dimensions length 0.415(+/-0.02) and width 0.144 (+/-0.008) inches. Because i have tombstone problem. My stencil design is 10 mils thickness in order to avoid the issue but it helped me just a little bit. Thanks in advance
Jan 9, 2003 | It depends on what the finished solder joint looks like after reflow. Use IPC to determine your sol
Dec 19, 2002 | Your area ratio for this aperture is fine (.78) usually any value greater than .66 will provide a reliable paste release. I would make sure however that the stencil is polished. I agree with other posts regarding your setup and/or paste type is probably the culprit. Russ
Dec 18, 2002 | One thing that will also cause this is very slight stencil mis-alignment. Sometimes the paste will have a tendency to hang up in the apertures if you are over hanging just a little on the solder mask. Some solder mask are very slick and will not pull the paste out of the apertures like
Dec 9, 2002 | You want to use a rubber squeegee with as high as a durometer as you can get away with, order two or
Dec 2, 2002 | Gerber[R] Data (File). Used in directing a photoplotter during printed circuit board and stencil artwork fabrication. Gerber Scientific Instrument Company used to be the dominant producer of the photoplotters used for "shooting" film, back when mechanical vector type plotting was the only way
Nov 21, 2002 | There have been a number of papers and articles on the subject as well as tutorials and workshops sponsored by SMTA, etc. I can send you a paper I presented in 1995 that may cover most of your questions. There are also many other resources that might help you: Printing equipment and stencil
Nov 7, 2002 | by insufficient solder due to poor registration, poor release, bad stencil design, etc., etc.,....
Nov 1, 2002 | Ive always preferred "Put another log on the fire" for those emotional moments. Why don't you tell
Oct 31, 2002 | Whoa, I have (for a long time) been under the impression that lead can only be absorbed via the mucus membranes, not through skin as in the hands. Did I miss something?? Not that I behave would much differently, other than donning gloves whenever I even touch a stencil or the printer controls. I
Oct 18, 2002 | If you have room try putting a small piece of tape on the bottom of the stencil right next the aperture that is giving you the problem. The added height of the tape (Kapton tape is usually about 3 mils thick) will likely give you a heavy enough deposit to make up for what the via erodes away
Oct 2, 2002 | Dave- thanx for the suggestion and I have already downloaded the catalogs of both companies you mentioned. I am trying to narrow down the list for the BGA patterns most commonly seen vs. the shotgun approach of making one of everything, just in case. My 3x3 configuration is to have a stencil in a
Oct 1, 2002 | No problem. A standard stencil is OK. You want to print a half moon shape on each side of the hole. Make sure you print about X2 the size of your hole and make sure you keep the print in close to the hole. You want to print X2 the hole size as to have enough to fill the hole with out voids.
Sep 18, 2002 | 1) For solder short, pls check the paste height. Too much vol will cause short. For 15 mils use 5 mils thickness stencil if possible. Check profile preheat time to prevent hot slumpof the paste. 2) type 4 powder will be better for 15 mils pitch comp
Jul 17, 2002 | Hello all, I have a question about OSP. The solder mask over traces leading to SMT pads, in some instances, does not cover all the way to the pad. Of course the stencil apertures do not include traces. After the SMT and reflow process, there is visible copper between the pad, and the beginning
Jul 5, 2002 | I have seen the U-shaped aperture on a customer site, being used with success. However, the problems with the stencil and the �loose� tabs where reportedly a reason to search for different aperture designs. Before this company could test their ideas of using two pads and four small circular
Jun 4, 2002 | We want to perform a "design of experiments" session to determine the optimum settings for our pasteprinter.We will design a stencil with decreasing aperture-sizes to make it measurable where the printing stops. The result should be a measureable printing quality. We think of : wieght before
Jun 4, 2002 | Hmmm... I know the Vitronics oven had bigger motors on em', but I don't think they're blowing molten solder balls around. You did say you changed your profile and stencil designs, which helped, but didn't exactly state what ya did. I believe this may be helpful.
May 10, 2002 | Does anyone know a surefire way to print micro-vias which are centered on BGA pads and also reduces solder ballooning? Would you design a process around two stencils? -- one for the vias themselves and one for the pads. Could you fill all of the vias then reflow - then print the pads, place
May 5, 2002 | tolerances I should be looking for on the vision system and the actual alignment of the stencil.
Apr 19, 2002 | If the solder balls are next to your discretes, you should consider a homeplate design on you stencil apertures. THe only other time we have seen soler balls is due to the raw card. If the vias are not plugged by the solder mask, solder and air can get in the holes. Then during reflow, the temp
Apr 11, 2002 | We use the ASC vision master 212, our customers wanted a height and volume measurement rather than a
Mar 28, 2002 | I realize that this is sort of off-topic, but do you have scads of solder beads (mid-chip solder balls, whatever you like to call them) with that stencil design? If not, would you mind sharing which paste it is that you are using? Email if you like. I'm just wondering if you're using one of those
Dec 20, 2001 | Hi Dafe F, The edge hold conveyor was installed due to the double sided process on our new products. Remember the Stencil Printing Adhesives versus Dispensing in the forum a year ago? Well that led us to acquiring a Camalot 3800...This time it's the oven's thermal profile issues... Thanks to your
Nov 26, 2001 | search the fine SMTnet Archives, like here: Nov 16, 2001 | John,
I have seen process mixed technology in customer site.Now they dont use wave but they print paste through hole components.It is good and fast but it did take a time when they found a right paste to do that.Stencil is plastic and aprox.3mm(3000um)thick.If you go that way it will not be easy
Nov 16, 2001 | John, I have seen process mixed technology in customer site.Now they dont use wave but they print paste through hole components.It is good and fast but it did take a time when they found a right paste to do that.Stencil is plastic and aprox.3mm(3000um)thick.If you go that way it will not be easy
Nov 12, 2001 | Thanks, Dave. Three courtesy cheers for specifications written to reflect the capabilities of the part suppliers, even if they fail to meet the purchaser's (not unreasonable) process req'ts. In the meantime, I'm sure my stencil guy would be more than happy to make 3 ea. for every board over 12
Nov 7, 2001 | Most of us, here on SMTnet, are either assemblers or sale types. Assemblers use stencils [metal foil, secured in a frame] instead of silk screens. Fabricators use silk screens in various photoimaging processes for applying etch resists, solder masks, and legends. Tell us where you go to college
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