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pads Electronics Forums search results
2406 results found for pads in 3s.
Showing matching items 1 - 50
- 97%
Reflow - 3/25/02 -
- ... the solder paste out to the sides of the print, and, if you are not careful, 0.4mm spaced pads short together very easily, becoming 0mm spaced pads. ;-) Also, the location of microvias in the LGA pads can cause opportunities for rework. If the out-gassing of microvias is violent enough, solder can bridge between pads when the microvias on adjacent pads are positioned in the same location on pads. Staggering of the location of microvias reduces, but does not eliminate, the problem. As mentioned ...
- 96%
adhesion to laminate - 7/10/03 -
- Micro BGA pads, adhesion to laminate A reading of the pictures is: A1: Looks like pad [B1] is smaller than the other pads. It?s weird that the pads are such different colors. A2: Looks like pad [B1] is smaller than the other pads. Solder mask opening [B1] is misregistered and seems smaller than other openings. Solder mask seems very thick, relative to the pad thickness. B1: Silk screen is closer to the pads than A1 and C1. B2: Silk screen is closer to the pads than A1 and C1. B3: All solder ...
- 96%
Micro Leadless Frame - solder wetting control - 5/8/02 -
- ... aperture openings b) PCB (Au/Ni) pads sizes and found the two coverage areas are mis-register, when superimposed on each transparency. E.5) the PCB pads have "up/down/in-out" Pads irregular pad layout; even when the gerber data shows all the Pads are supposedly equal in Pads dimensional lengths and equal dimensional PCB layouts. E.6) the stencil was generated using customer supplied gerber data of the silk-screen layer. this gerber supplied to us assumes all pads are of equal layout and ...
- 95%
RF board not soldered - 10/19/08 -
- ... x 1". The pads are in the bottom of the PCB and it goes on the Top side of the mother board the pads of the RF board are like a BGA (square pads)and we have troubles to make the proper welding in the pads of the RF board with the pads of the mother, the problem is just with one pad not all of them. between two pads there is a via hole, I do not why is the reason of this hole, one of the pads that is just beside of this hole is the one with the issue with not proper welding between pads. Any help ...
- 95%
Very fishy missing solder paste issue - 7/19/05 -
- ... bottom-center pads. It is on the bottom outside-bottom pads. Notice curious fuchsia color that's in "stipes" on raw solder and dots at the edge of some silk screen legend. There is some raw solder off the bottom pads. 0408%20Missing%20Solder%2003.jpg - Paste is not missing from the upper-right-center and lower-right-center pads. It is on top of the component and on the outside and left-center pads. Paste that originally was on the left-center pads is on the outside left pads. Curious fuchsia ...
- 92%
BGA pads lifting from PCB - 7/2/09 -
- BGA pads lifting from PCB On first glance it looks like those particular pads were not attached to any traces. If I had to guess I would say that your rework profile got hot enough to melt away the glue holding the pads to the board and they came away with your part when you lifted it off the pads due to surface tension with the solder. This can be a problem sometimes because those pads are not attached to any other copper they heat up more quickly. I would recommend attaching a thermocouple to ...
- 92%
MPM AP/A Problem - 10/8/07 -
- ... on this board (if the answer is yes, this is a good thing! no need to troubleshoot the mechanics of the unit.) 2. Are you using fids or pads for alignment? If you are using pads, try the following "teach vision" method; Enter teach vision and delete all models. Find two devices on opposite corners of the board which will allow you to see at least two of the pads on the monitor screen. (a 20 or 25 mil pitch QFP is VERY good to use!) Center the end pad of the device in the cross hairs and hit next ...
- 92%
Re: solder mask between qfp pads - 8/20/99 -
- ... solder mask between qfp pads | | | | | | One of the DFM suggestions I've seen is to remove the solder mask web, i.e. the mask between pads on 20-mil QFP devices. The rational is that if the mask is thicker than the pad the mask can prevent the stencil from making intimate contact with the pad and allowing solder paste to squeeze under the stencil and encouraging solder bridging. Another school of thought seems to be that the solder mask prevents bridging between pads. Anyone have experience ...
- 92%
BGA Rework - Pads being lifted - 4/4/09 -
- BGA Rework - Pads being lifted Cause: Solder between the pad and the BGA on the pads being lifted has not melted. So, when you lift the BGA, you also lift those pads with the unmelted solder with the BGA. These pads are probably sinking the heat to a large copper plane in a inner layer of the board. Solution: You may want to add more heat to the board prior to lifting the component. Do this through: * Longer preheat * Increased bottom side heating * Longer soak Each component on each board may ...
- 92%
Re: BGA Repair Problems - 8/17/98 -
- ... pad and terminations during replacement all the pads should be flat prior to replacement. Solder wick may be used with a soldering iron or a vacuum de-soldering tool with a flat ended vacuum tip. A flat blade soldering iron tip is also a good method for pad flattening. If there is no evidence of spiking on pads due to the correct use of flux, solder removal may not be necessary. Removal of the solder to flatten the surface does make life easy. Pads may be re-coated with flux prior to placing the ...
- 91%
Solder Mask Defined Pads - 2/23/00 -
- ... be reworked. Are my concerns justified? Am I missing anything? One of the primary reasons of using SMD pads is to increase the surface area between the copper and the resin to reduce the possibility of damaging pads during rework, correct? Believe me, I'm not about to ignore this possibility as we have had pads damaged when BGAs have been replaced on a couple of occasions but can't we also decrease the risk of damage by using a higher Tg material (maybe Tg=210 or so)in the fab of the PCB's? I ...
- 91%
Solder Mask Defined Pads - 2/23/00 -
- ... be reworked. Are my concerns justified? Am I missing anything? One of the primary reasons of using SMD pads is to increase the surface area between the copper and the resin to reduce the possibility of damaging pads during rework, correct? Believe me, I'm not about to ignore this possibility as we have had pads damaged when BGAs have been replaced on a couple of occasions but can't we also decrease the risk of damage by using a higher Tg material (maybe Tg=210 or so)in the fab of the PCB's? I ...
- 91%
Solder not reflowing properly - 9/28/08 -
- ... linear to 210?C at 1?C/sec, > then peak. another thing: are the hot air > blowers of your oven running at the correct > speed? too much air flow on the small pads will > exhaust the flux more rapidly. > small pads like 0402 tend to get hot quite > easily. looks like excessive heat is your problem > here. pads are wetted, component leads are not. > this means solder paste flux on top layer was > exhausted before entering in reflow. your profile > is the 'in-between ...
- 91%
LGA36 6.5 x 3.5 mm - 3/24/07 -
- ... a QFN but it has no surrounding pads. It just looks like a uBGA with pads instead of bumps or balls. I forgot to mention that the device has 4 outer oval dummy pads (~1.15mm away from each corner) and the size of these is 0.7 x 0.35mm. The PCB has oval solder pads for these 4 oval outer dummy pads as well. I guess that will help a littlte bit to self center. But I'm still not sure how to do the process properly. So totally: LGA 36 + 4 outer oval dummy pads which I don't understand the need for ...
- 91%
Skewed transistors - 4/18/03 -
- ... be patient.] your situation is: * Sometimes you get TO252. * Other times you get TO263. * Each part has different lead configurations / pads. * One part works with the pad configuration you have, but the other part does not work. * Part that doesn?t work skews. [We bet it's the TO252 that's floating on the TO263 pads.] Assuming your TO252 and TO263 pads look like these, http ...
- 91%
Solder Spotting on Gold - 8/6/98 -
- ... vigorously failing the products at final test or during goods receipt if products are contracted out. If the surface of the pads are to be used for interconnection then any contamination may not be acceptable. Contact strips, LCD interconnection or key pads are examples where solder contamination may cause mechanical connection failure of intermittence. This would have cause be related to the position and the size of the spots. It is however much easier to just reject the products than make a ...
- 91%
Pad Sizes - 12/24/98 -
- ... to solder paste printed off the metal conductor pads, I can't believe I will get much of a solder fillet since the component will be bigger than the pads, maybe tombstoning will occur, I would also think the component will float on the solder and will end up tipped after the solder cools, I hate to think what will happen if the component is placed 50% off the pads by the pick and place machine The production manager says he used undersized pads for 0402 components where he worked before and it ...
- 91%
Tomb Stoning - 7/16/99 -
- ... 1 was originally required. Round test pads near this area will be used to complete this circuit rework, however these test pads are not the proper size. 1 end of each chip component will share a single test pad, the other ends of these chip components will be soldered to separate pads. Tomb stoning will result during automatic solder reflow unless the pads are trimmed to the proper size. The question is what should the relative size of these 3 pads be to eliminate tomb stoning. 1 pad will share ...
- 91%
De-wetting on Immersion Silver finish board - 8/24/00 -
- ... De-wetting on the smt pads and componenent termination on the bottom side after top side procssed through reflow. Board finish is immersion silver. ? Any recommendation on what we should check & verify * Problem is random in nature. Not component related * De-wetting only on the bottom side after top side reflow * De-wetting only on chip components/pads * There are vias on pads but the problem is not correlated with these pads * No apparent contamination on the pads * Have not verified the ...
- 91%
BGA ball vs land design problem?? - 6/2/09 -
- ... pads caused voiding. Your supplier is correct that the pads on the board should be the same size as the pads on the interposer, but this is to improve reliability issues. Search the fine SMTnet Archives for more on BGA voiding. Finally, we're not wild about your supplier using solder mask defined [SMD] pads on the interposer. * Motorola did a study in 1996 that indicated that nonsolder mask defined [NSMD] pads were significantly more reliable. * 3.1X Life Improvement of NSMD over SMD Pads [
- 90%
Soldermask Defined BGA Pads - 10/14/04 -
- Soldermask Defined BGA Pads We are experiencing a problem with soldermask defined BGA pads not accepting solder during the reflow process. The paste is there when the boards come off the printer but after reflow, no paste. Some other pads in the same pattern are fine. Here is the really weird part, we only saw it on 3 of 6 boards. The other 3 were fine, 100% coverage. Opening sizes are .012 round. Our process reflows the boards without components so we are expecting a meniscus of paste on the ...
- 90%
BGA Via Plugging - 2/19/02 -
- ... in use for Au finger connectors on a regular basis). Via Pads (underneath BGA) - On Top The via pads on the top (underneath) the BGA should be covered to prevent the solder from wicking into the PTH. The via pads on the top side cannot be used anyway since they are covered by the device ...
- 90%
adhesion to laminate - 7/9/03 -
- Micro BGA pads, adhesion to laminate Our company applies solid solder to surface mount lands. While processing a micro BGA design we had some pads fall off, peel, whatever you might call it, from the surface of the board when touched "GENTLY" with the tip of a blade to remove a small squeeze out. The pads fell off so easily it seems like it may have been a clad copper to laminate issue. Most of the pads in the footprint were soldermask defined, a larger trace with the soldermask opening creating ...
- 90%
BGA PCB Pad size - 1/17/03 -
- BGA PCB Pad size How do 0.5 mm pads on the board help paste release from the stencil? Paste release from the stencil is a function of: * Paste * Printer operation * Stencil design You have no obligation to made your stencil apertures the same size as the pads on your board. You should deign your stencils with the area and apect ratios described in the fine SMTnet Archives to get good release. You should make the pads on your board according to suggestions of your component fabricator. We don't ...
- 90%
adhesive on pads - 4/1/02 -
- ... over the place was an exaggeration. I don't actually see any adhesive in the connection. The arc of the compressed glue dot extends onto the pads slightly, but is not visible post-wave, and not typically (when centered) under the termination of the part. All that is visible is adhesive flush with the pads, since solder fills in on the sides of the pads. I just know the adhesive is in there from pre-wave inspection. In other words, it's not a defect, but I don't much like it. My concerns about ...
- 90%
Re: Wetting Balance Equipment - 8/17/98 -
- ... tests were conducted using the Multicore Must 2 wetting balance incorporating a micro globule to test surface mount pads. Two methods were evaluated on sample copper pads measuring 0.050" x 0.040" finished with a nickel/gold finish. Samples were removed from a circuit board featuring a series of five pads and finished so that the edge of each of the pads extended to the edge of the board. The board sample was then placed in a modified holder to allow the board sample to be lowered at ...
- 90%
Design guidelines for solder thief pads - 5/7/99 -
- ... pads This is not strictly a surface mount query but any input welcome I am thinking of using surface mount solder thief pads for a through hole connector. The connector is two rows of 0.1" pitch pins and on waving there is often a bridge on the last two pins. To ease the layout overhead, we want to put the pads at either end of the connector to enable the PCA to be layed out/ reflowed either way round. Does anyone have any experience of doing this, what would the implications be of putting pads ...
- 89%
QFN Rework - 7/18/08 -
- ... solder on all the pads, My plan was that a LITTLE solder on the center pad would wet and center the device (using a gel flux) with our BGA hot air rework station. Then we would touch each pin with a tiny iron to make the pad connections. Well we had it nicely lined up on the gel paste, then reflow was good, but it shifted (nice and square) ONE SET OF PADS offset. Rev two of this attempt will be to put less gell flux on, and a tiny dab of paste the pads, hoping to have the PADS do the alignment ...
- 89%
conformal coating - masking problem with ammonia - 5/12/09 -
- conformal coating - masking problem with ammonia We do a conformal coating for a customer with copper-nickel-gold pads on his board. The pads are masked prior to coating with a standard gel, containing ammonia. After thousands of boards, being processed like this, now the gold pads seem to be less solderable and the pads have dark/brownish areas. Can anyone help me? What has happened here? Any known chemical reaction with copper seems possible but what is so critical in NiAu-processes ...
- 89%
Criteria for Min Thickness regarding Large and Small pads - 6/18/08 -
- Criteria for Min Thickness regarding Large and Small pads Does anyone know of an established guideline for thickness requirements? Our smaller pads continue to receive a thicker solder deposition when we measure by the larger pads for process accessibility and vice versa for the larger pads when we measure by the smaller ones ...
- 89%
via under a smd pad ? - 11/21/07 -
- via under a smd pad ? From info I have been told from design standpoint, via in pads helps with managing EMC issues with working design, in particular for high speed digital/dense populated type PCB's. We had a manufacturing customer that had very low yield because of this via in pads was two big and solder was drained away from the pads - 1000s of pads on design - lots of rework. It can be done but via size has to be as small as possible, or preferably plugged vias used with solder. This all ...
- 89%
via under a smd pad ? - 11/14/07 -
- ... micro-vias in 0805 and larger pads, with no issues. But my most recent project had vias that were larger than the 0402 pads that the via was in. To the point that for a number of the lands, there was no visible pads (a couple of them...you could actually see a sort of outline where the pad would have been, but all of the plating was taken up by the ring of the via). The determination was that the designer definitely used vias that were too large for the pads that he used them on. I couldn't give ...
- 89%
Defect reduction on RF design - 9/19/05 -
- ... a customer that produces RF based assemblies. We are building several board types for them, all of which have an "RF" area of the PCB. This RF area does not have any mask to define pads. There are also several issues with components sharing pads, unequal thermal mass between pads and via's on some of the common pads that "thieve" the solder. The net result is an unacceptable amount of tombstones and shifted components. We have worked extensively to develop a profile that minimizes thermal delta ...
- 89%
PROBLEM IN ONE COMPONENT (0603) - 7/16/05 -
- ... Investigate the possibility of imbalanced forces by: -- Comparing the pad layout of this component with the pads of other 0603 on the same board [sometimes a wide spacing between pads will cause this] -- Inspecting the paste pring process to assure that equal amounts of paste are applied to both pads. -- Reviewing the accuracy of the component placement to assure that the component is positioned between the pads. Consider searching the SMTnet Aechives for previous discussions on trombstoning ...
- 89%
solder mask onto pad or pad defined by solder mask? - 12/9/04 -
- ... mask? We did this for BGA pads, but have not thought about other types. So, this may or may not apply for those. Pad defined by:||Advantages||Disadvantages Non-solder mask||No point-of-stress concentration at edge mask and solder ball||Smaller pads have poorer adhesion strength, performance in rework and multiple reflows, and heat dissipation ||No CTE mismatch at edge mask and solder ball|| ||More space for routing traces between pads|| Solder mask||Larger pads have better adhesion strength ...
- 89%
Solder ball crack - 5/10/04 -
- ... definitions, the two main types for solder masking near BGA pads are: 1 Pad, Non-Solder Mask Defined. In circuit board design, pads with spacing that does not allow solder (usually bumps) on the pads to contact the adjacent solder mask. [After reflow, this ends-up being a potato shaped ball, when looking at a section.] 2 Pad, Solder Mask Defined. In circuit board design, pads with spacing that allows solder (usually bumps) on the pads to contact the adjacent solder mask. [After reflow, this ends ...
- 89%
Reflowing a PowerPak SO-8 - 11/6/03 -
- ... with no solder on the pads. Generally, any device that has bare pads under them that attach to corresponding pads on the board qualifies as a land grid. Third, watch out for LGA with a thermal "slug" under them, like a QFN [and the drains on your MOSFET]. The slug really limits the options if overprinting. If the opening for the thermal slug is too great when using blades (not a pump), the blades can "scoop" paste from the center of the deposit for the slug. Since the pads do not get scooped ...
- 89%
Solder Paste and fine pitch components - 9/18/02 -
- ... between the pads? If yes, that helps. If > not, pay close attention to stencil aperture > width and be sure that the aperture deposits less > paste by 1-2 mils per pad, centered on the > pad. I had the exact opposite experience with solder dams on 15 mil pitch. When the board shop tried to put solder mask between the pads, the pads were too small. We couldn't make the aperatures smaller than those pads because there would be no opening left if we had. The result was pads smaller than ...
- 89%
OSP / Paste Printing Problems - 8/29/02 -
- OSP / Paste Printing Problems Problem description: pads of PCB:s seems to "reject" solderpaste. Problem is more easy to identify on larger pads where the paste forms a double layer of paste on the other end of the pad and on the other end there is no paste at all. On smaller pads, on same boards where we have problems also with bigger pads, there is no paste at all on some areas of the PCB ...
- 89%
Solder on gold LCD pads - 10/5/01 -
- Solder on gold LCD pads I have had an issue where solder has contaminated gold plated pads (fingers) where it is not acceptable. The pads must remain perfectly coplaniar for a LCD zebra strip to lay accross them. Does anyone know of a way to remove the marriage level of solder (tin/led) from the pads without damaging the circuits on the PCBA? I have looked into reverse electroplating, but I have concerns about pumping current into the board. Dan Steffler Quality Process Specialist e-mail:
- 89%
Re: solder thief guidelines - 8/4/98 -
- ... the larger thieving pads I've never seen a bridge on a 50-mil pitch SOIC. One other thing about SOIC pads that you can do to reduce the bridging on the bottom, is to make the pads .020" wide, it's a little narrower than what IPC calls out, but it reduces the chance of shorts when wave soldering. Also, if you're only gonna put the pads on the trailing edge of the SOIC, be absolutely sure of what that direction is gonna be, it would suck a little bit to lay the pads out for one direction and ...
- 89%
Re: solder mask between qfp pads - 8/18/99 -
- ... solder mask between qfp pads | | | | | One of the DFM suggestions I've seen is to remove the solder mask web, i.e. the mask between pads on 20-mil QFP devices. The rational is that if the mask is thicker than the pad the mask can prevent the stencil from making intimate contact with the pad and allowing solder paste to squeeze under the stencil and encouraging solder bridging. Another school of thought seems to be that the solder mask prevents bridging between pads. Anyone have experience ...
- 89%
Re: solder mask between qfp pads - 8/16/99 -
- Re: solder mask between qfp pads | | | | One of the DFM suggestions I've seen is to remove the solder mask web, i.e. the mask between pads on 20-mil QFP devices. The rational is that if the mask is thicker than the pad the mask can prevent the stencil from making intimate contact with the pad and allowing solder paste to squeeze under the stencil and encouraging solder bridging. Another school of thought seems to be that the solder mask prevents bridging between pads. Anyone have experience ...
- 89%
0402 tombstoning - 4/11/02 -
- ... these defects, but multiple factors that need to be tuned to work well together. PAD DIMENSIONS * Some SM-782 pads are a bit archaic. 7525, Philips, and Topline pads are more in touch. Suppliers are the best source of information. Go there first. Everyone else is sheep. Baaaa. * At some point of development, the gap between pads is probably more critical that the size of the pads. Pads that are closer are better than those further apart. Something like 18 thou is better than the more common 25 ...
- 88%
BGA dropping off the board - 2/14/08 -
- ... solderability with an iron like mentioned before. If you don't find that the pads are contaminated or masked over lightly and the pads do take solder effortlessly, you got something special there. Are you sure there are no other close by locations that aren't showing some kind of wetting issue? If you are running lead-free and the solder got hot enough to melt and meld with the BGA balls leaving nothing on the pads whatsoever...the only explanation is the lands. IOs it possible the board house ...
- 88%
Reflow Profile Design - 6/19/07 -
- ... but is not soldered at all on the pads, then you can discard BGA solder issues, by the other hand; you might be experiencing wicking due to heat is being absorbed on component so the balls on BGA are hotter than PCB pads. I know that is hard to measure temperature on lower side and higher side of the BGA ball, maybe you can try increasing bottom side temperatures on the zones that are affecting preheat+soak (below 217?C) to try to get more temperature to pads below BGA. The lower the Cooling ...
- 88%
ICT bare board - 3/12/07 -
- ... availability of test pads, access to test pads, and type of component being tested. Test coverage is counter balanced by the cost of test that is primarily driven by complexity of the test fixture and the test program, and maybe machine test time [duration]. Using test pads is better practice. Q2.? testing the pathes will be done in final assembly or on the naked board? A2. Testing of traces and interlayer connections is done most often on the bare board by probing pads. Commonly, In-Circuit ...
- 88%
caps moving from pads - 9/21/05 -
- caps moving from pads I am going to agree with Rob a little. It is also possible that a internal ground plane might be under or connected to the pads of this cap thus causing a increase in temp to this part during reflow. This can cause parts on occasion to jump from the pads. It is also possible that some of the parts are contaminated and are rejecting solder. If so, during the liquid stage of reflow the blowers can blow the part away from its location. I think the simple fix is to possibly ...
- 88%
BGA attach eval. - 4/3/03 -
- BGA attach eval. R1: Contacting Altera to find out if the BGA pads are gold. D1: Bet money the pads were ENIG. R2: Contacting Altera to find out if they use abrasives. D2: If abrasives were the problem, you?d see it in many pads, especially those close to the problem pad. R3: Could one expect to see a flat pad with a forcible removal? D3: We?d be surprised not see lifted pads. Lifted pads are flat, right? Lifted pads indicate a good solder connections. Mmmmm, flat non-lifted pad doesn't sound ...
- 88%
BGA rework and inspection - 5/30/02 -
- ... the solder resist between the pads and vias (I can't comment on your boards.. I'm just bringing up problems that we have seen). This leads to bridging, and the vias rob solder from the joint. We do not believe we will be able to 100% eliminate this issue, and some degree of resist touch-up may be required on the occasional board, but we have made it a darn sight better by using a 'PACE VF100' rework unit, which both blows hot air and has vacuum to 'hoover' the pads clean. This limits the ...
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