Fullscreen HTML5Med Res (??MB)HTML4

Nicholas Vinen takes a brief look at what’s available in SMD Hardware. . . Soldering SMDs: it’s becoming unavoidable If you’ve been reading SILICON CHIP for a while, you will have noticed that from time to time we publish projects which use surface mount devices (SMDs). We’ve tried to avoid them where possible because many, probably most, home constructors and hobbyists are at least a little apprehensive about using them. For some, building a project which involves one or more surface mount devices may deter them completely from building the project. And that’s a shame. The problem is that SMDs are not going to go away – we find we have to use them more and more often. There is a simple reason for that: many newer ICs and semiconductors are not even produced in through-hole packages. So if you can’t beat ’em, we need to help you join ’em! What are the major problems, apart from the fact that SMDs are (usually) very much smaller than their through-hole counterparts and even people with perfect eyesight often need a magnifying glass or loupe to identify them? Probably the biggest is that there is definitely less margin for error – due of course to the thin tracks required for parts with close pin spacing. It doesn’t take a lot of excess heat to lift tracks off the circuit board and repair can be tricky. Another difficulty is one identical with through-hole semis: too much heat risks damaging/destroying them. But it’s easier to apply too much heat with SMDs! Having said that, if you have a steady hand and some patience, with a bit of practice, dealing with SMDs becomes fairly straightforward. It really helps to have the right tools. In this article we take a look at a selection of tools which make soldering both surface mount and through-hole devices easier and quicker. This is not the first time that we have written about SMD soldering. Our previous articles have touched on several different techniques suited to specific types of packages, as there are many SMD package types, each of which requires a different approach. For our previous tutorials see How To Hand-Solder Very Small SMD ICs (October 2009), How To Solder Surface Mount Devices (March 2008) and Working With Surface Mount Components (January 1995). Those articles covered mainly the “how to” aspects. Here, we are going to look at some of the specialist equipment available. It is by no means an exhaustive list – in fact, much of this article has been generated by various suppliers submitting equipment for review. It seems they too are now firmly hitched to the SMD bandwagon! Nor are we suggesting that all of this equipment is required by the enthusiast, though all of it can be used by hobbyists (noting the sometimes deep pockets required and also sufficient volume of construction to warrant it!). But it will give a good idea of the type of equipment that is already being used extensively in industry, service/repair and electronics laboratories in Australia and around the world. siliconchip.com.au December ecember 2010  11 JBC BD-A Digital Soldering Station H ave you heard of JBC soldering stations? We hadn’t either and didn’t know what to expect. What we discovered is a serious unit with some excellent features. We only had this evaluation unit for a short period but during that time it quickly became apparent that it is something special. Like many modern soldering stations it features digital control, which allows the tip temperature to be precisely set and monitored. Two handpieces are available, the standard-sized T245 and the T210 lightweight, fine tip version. The base station has an LCD display and keypad along with the integrated stand and metal wool for cleaning. That’s all pretty straightforward but when we started using it we made some pleasant discoveries. Clever temperature management JBC have designed the heating element and tip in a way which gives two advantages over other models we have tried. Firstly, because the tip is light and has very low thermal mass, it heats up rapidly. We thought our existing soldering stations were pretty good – they get up to temperature from cold in about 30 seconds – but this one blows them away. It’s so fast that you can switch it on, sit down, grab the board you want to work on and it’s ready to go. It goes from cold to 350° in two to five seconds, depending upon the tip used. That may not sound like a huge advantage since you can always turn your station on and do something else for half a minute. But if you are like us, there are many times that you 12  Silicon Chip just need to replace one component or make some small change on a PC board “Mini-wave” soldering tip – and then you for the T245 handpiece. might need to do it again in five minutes. In situations like that the time savings can add up. The second advantage is that there is a sensor in the stand which can detect the presence of the handpiece. As soon as you finish soldering and put the handpiece down, its temperature is lowered to around 220° (this can be adjusted). The LCD shows “SLEEP MODE”. As soon as the handpiece is removed it is brought back up to the working temperature so fast that you need not even be aware it is happening. This sleep mode function not only saves power but it extends tip life since they oxidise faster when they are hot. What’s more, because the station knows when the handpiece is on the stand, it can keep track of how long it has been since you last used it. After thirty minutes of idle time (also adjustable) it switches the heater off entirely. This provides great peace of mind in case you accidentally leave the iron on – the tip will be protected and the risk of fire or other damage from a forgotten iron is minimised. It also means that you can leave the iron switched on for those times when you may be using it intermittently without worrying about when you might next need to use it. siliconchip.com.au Just a tiny selection from the huge range of tips available for the JBC BD-A. Environment the Environment Energy && the Saving Energy Lighting -- Saving LED Lighting LED Tube ecoLEDTube ecoLED lamps fluorescenttlamps tofluorescen alternativeto friendlieralternative Thefriendlier The Multiple tips Like any decent iron, the JBC BD-A has a large selection of different tips, many of which are designed for use with SMDs. These include: conical, chisel, knife, angled, spoon (miniwave), notched (for SMD components), U-shaped (for inline ICs), rectangular (for quad flat packs), etc. A problem we have faced in the past is that changing tips takes some time. First you must switch off the heater element and wait for the tip to cool down, then unscrew the retaining nut, remove it, attach the new tip, tighten the nut back up and wait for it to heat up again. This process can take a frustratingly long time, making jobs which require many different tips (eg, building a board with a mix of SMD and through-hole components) difficult. One solution is to use multiple soldering irons but obviously this is not ideal. The BD-A solves this entirely with a very clever tip attachment scheme. The stand has three “parking” locations for tips built into its base. While the iron is still hot, you can place the tip in an empty slot and then pull down and back. This extracts the tip, leaving it in the slot. The handpiece can then be pushed down onto another different tip in another slot and once it’s in, it heats up rapidly. The removed tips cool down quickly too, so you can take them out of the stand and swap in another virtually straight away. This is an invaluable feature for working on surface mount or mixed boards, where you might be switching between several tips frequently: a fine one for small components, a larger one for big components, a wave tip for multi-pin devices, a notched tip for soldering chip resistors and capacitors and so on. friendly allyfriendly environmentally lead,environment nolead, mercury,no Nomercury, No maintenance Lessmaintenance life,Less Longerlife, power,Longer Lesspower, Less Lamps FluorescentLamps T8Fluorescent retrofitT8 Canretrofit Can irritation noirritation buzzing, no no flicker, no buzzing, no strobing, flicker, Nostrobing, no No saving costsaving energycost power,energy thepower, Halfthe Half maintenance lowmaintenance verylow life,very Longerlife, Longer FlexibleLED LEDLights Lights Flexible RGBMulti-colour, Multi-colour,White, White,Warm WarmWhite. White.24VDC. 24VDC. RGB Cuttotolength. length.Remote Remotecontrols controlsfor forcolour colour&&dimming. dimming. Cut Withwaterproof waterproofseal seal With andadhesive adhesivetaping taping and (non-sealversion version (non-seal alsoavailable) available) also Covelighting lighting Cove Other options The options for this iron are comprehensive. There is a third handpiece style which is identical to the standard T245 but with a heat shield for extra comfort during long sessions. Also available is the T245-NA handpiece with nitrogen nozzle and a fume extractor. The station itself is available in several versions. The DD-A is a dual station which accepts two handpieces and the DM-A is a quad version. JBC also make stations with automatic solder feed and vacuum for desoldering/reworking. Barlighting lighting Bar Price and availability The JBC BD-A has a two year warranty and is available with either the T245 or T210 soldering handpiece for A$614.50+GST. Get it from Mektronics (www.mektronics. com.au). Additional handpieces cost A$122.29+GST or A$163.06+GST with the comfort grip. Orders can be placed via their web site or call 1300 788 701 (or, in South Australia (08) 8346 0333). For more information e-mail sales<at>mektronics.com.au siliconchip.com.au Console Console Kickboardlighting lighting Kickboard Colourchanging changing&&effects effectsvia viaremote remotecontrol. control. Colour Setsthe themood mood&&atmosphere atmospherefor foryour yourvenue. venue. Sets Sydney: Sydney: Melbourne: Melbourne: Website:www.tenrod.com.au www.tenrod.com.au Brisbane: Website: Brisbane: E-mail:sales<at>tenrod.com.au sales<at>tenrod.com.au Auckland: Auckland: E-mail: Tel.02029748 97480655 0655 Tel. Tel.03039886 98867800 7800 Tel. Tel.07073879 38792133 2133 Tel. Tel 0909298 2984346 4346 Tel Fax.02029748 97480258 0258 Fax. Fax.03039886 98867799 7799 Fax. Fax.07073879 38792188 2188 Fax. Fax.0909353 3531317 1317 Fax. December 2010  13 Manual Wave Soldering H and-soldering fine-pitched SMD ICs can be a challenge. But it is sometimes necessary, typically when repairing commercial equipment or assembling boards which use ICs not available in through-hole packages. For surface-mount chips with larger pin spacings, hand-soldering is possible with a regular iron (made easier with a fine tip). Examples of such IC packages include Small Outline Integrated Circuits (SOIC) also known as Small Outline Package (SOP), SOT-223 (Small Outline Transistor type 223) and D-PAK (TO-252). Other packages are hard to hand-solder with a regular soldering iron. Common such types include Shrink Small Outline Package (SSOP), Molded Small Outline Package (MSOP), Thin Shrink Small Outline Package (TSSOP), Thin Quad Flat Pack (TQFP), Quad Flat pack No leads (QFN) and SOT-23 (Small Outline Transistor type 23) variants. We hope you have studied all those initials – there will be an exam later . . . With practice and special techniques SMDs can be reliably soldered with a regular iron but there are easier ways. Those who work frequently with fine-pitch SMDs prefer using special tools that make the job a lot easier. One inexpensive tool is the “mini-wave” soldering tip or spoon tip. This is essentially a regular chisel tip with a semi-spherical depression in the otherwise flat face. When solder is melted in the depression, it stays there due to surface tension. At this point we should pause and explain the name. Wave soldering is one of the two major means of large scale PC board assembly (the other is infrared reflow). This involves a large solder bath which is kept liquid. In it, a series of waves are created. Each board is passed over the bath and the tips of the waves touch its surface, to which flux has already been applied. The surface tension of the solder causes a small amount to adhere to the pads and pins of each package – just enough to make a solid electrical and mechanical connection. The advantage of wave soldering compared to reflow is that it works well for both surface mount and through-hole components. What does this have to do with the manual wave soldering we are about to describe? Not a lot, except for the fact that the solder surface tension is an important part of both processes. Essentially, the movement of the soldering iron across the IC pins has the same function as the solder wave. In use, first the IC is tacked down (usually by hand-soldering at least two corner pins), then a layer of flux paste is spread over the rest. 14  Silicon Chip The next step requires a bit of practice but isn’t too hard once you get the hang of it. With some fresh solder in the depression, the tip is placed against the first pin and dragged along that row. This vapourises the flux which allows the solder to flow freely. Surface tension pulls exactly the right amount of solder out of the depression and onto each pin. How quickly the soldering iron is moved depends on the exact flux and temperature used (typically 260-280°). It is easiest with a viscous flux that does not vapourise quickly - and in that case, a slow and steady motion is best. With faster vapourising flux, the motion of the iron must be quick but smooth. The flux we used boiled fast so it took us a couple of tries to get the timing right but once we did, it all went smoothly. The photo shown here is an IC we soldered using this technique. It is a 28-pin TSSOP package and the whole procedure from start to finish took about 30 seconds and resulted in no bridged pins. If one or two were bridged then all it would take is a little flux and some solder wick to clean it up. Here’s a handy hint: if you are right-handed, tack the IC down using the upper-left and lower-right pins. If you are left-handed, tack it down using the other two pins. This is important because it is easiest to drag the iron starting at the top of the IC in your primary hand. If you tack the IC using the wrong pins then it will move when you apply the iron, resulting in a skewed solder job. Mini-wave soldering tips are not available for all irons but most major manufacturers make them for their higherend models. We used a JBC tip with the JBC BD-A soldering station provided to us by Mektronics. Hakko also make mini-wave tips (type ETGW or BCM/ CM) but not for all their models – we are out of luck with our FX-888. There are mini-wave tips available for Hakko models FX-950, FX-951 and FM203. www.hakko.com www.mektronics.com.au siliconchip.com.au SMD Soldering Tips P assive surface mount components such as resistors, capacitors, inductors etc can be soldered in place one pin at a time. However, removing them is much more difficult because the wide, flat pins do not have much “give” and it is virtually impossible to remove enough solder from each pad to get the component free. The obvious solution is to heat all the pads at once but that is difficult with a regular soldering iron. One solution is to use an SMD “tweezer”-type soldering iron handpiece like the Altronics T2461 (see photo above) which essentially has two tips with an adjustable gap between them. Alternatively, you can buy special forked tips for some regular handpieces. The notch in the middle is sized for specific surface mount components case sizes. Typical sizes are imperial 0603 (1.6 x 0.8mm), 0805 (2.0 x 1.2mm) and 1206 (3.2 x 1.6mm) and many manufacturers (eg, Hakko, Micron, JBC) make tips suitable for each. These are also suitable for soldering small surface mount ICs, such as those in SOT-23-5/SOT-23-6/MSOP-6 packages, as shown in the photo (above right). The tip shown here is from Hakko. This shape is available across a wider range Photo: Aisart, Wikimedia Commons. siliconchip.com.au (Above): while most commonly used when working with passive (“chip”) components, these tips can also solder small ICs. In this case, it is an SOT23-5 package. There are interchangeable tips like these available to suit most of the better soldering stations. (Above left): Altronics all-in-one “tweezer” SMD iron, where both tips are heated allowing both sides of an SMD device to be soldered at once. Both these devices do roughly the same job, although the tweezer-type iron doesn’t require a change of tips for different devices. of their models than the mini-wave tip mentioned earlier. Buying a selection of such tips tends to be much more affordable than purchasing specialised surface mount soldering tools. One challenge with using them is that if there is enough solder on the component, sometimes it can stick to the soldering iron when lifted off the board. In these cases, the component can be removed using tweezers. It is even possible to get specialised tips for soldering/desoldering larger surface mount ICs, including quad flat packs. These are made from a metal sheet which is folded to provide a contact area for each row of pins. While they tend to be trickier to use than hot air rework stations for desoldering, they can come in quite handy for soldering replacement ICs in place. • www.altronics.com.au An SMD tweezer handpiece which plugs into a soldering station. These are more expensie than the Altronics iron (above) but they are slimmer and lighter, making it easier to work with smaller components and on crowded PC boards. December 2010  15 Micron T-1260 Vacuum Desoldering Tool M ost readers will be familiar with “solder suckers” – the hand-driven vacuum pumps used for component removal. Pressing the plunger compresses a spring and it latches in place. When the release button is pressed, spring force pushes the diaphragm up through the cylindrical chamber, generating suction at the tip. If the tip is against molten solder when the plunger is released, much of the solder is sucked into the chamber – hopefully enough to free the component lead. While solder suckers are cheap and can be used to remove many types of components, they have several disadvantages. Firstly they require dexterity to use properly, as the tip must be placed accurately against the molten solder and the plunger released in quick succession, otherwise the solder will not be completely sucked away. Due to the limited amount of suction available, it can take multiple tries (and possibly also the use of other tools like solder wick) to get the lead free of the board, especially on boards with plated through-holes. Reliably removing multi-lead components without destroying them can be difficult. You also need to regularly clean the chamber and tip, otherwise 16  Silicon Chip over time the suction drops. The diaphragm needs to be re-oiled after cleaning or else the seal will eventually fail. The plastic tips also need to be replaced periodically. Having said all that they are still a very handy item in the electronics toolbox. But what do you do if you need to regularly and reliably desolder components? The answer is a powered vacuum desoldering tool such as the Micron T-1260 from Altronics. We actually purchased this unit, thinking it would come in handy occasionally – but now we use it frequently because it’s so much more convenient. Usage The most important improvement over a solder sucker is the fact that the vacuum tip is heated. Basically, it is a soldering iron with a hole though the middle. The T 1260 is temperature controlled but it also has a lot of thermal mass, which can be an advantage when removing large components or those mounted on copper planes. However, it takes a few minutes to come up to temperature. The temperatures used are a bit higher than typical for soldering, generally in the range of 350°-425°. This is because desoldering involves melting solder where most of the flux has already boiled away and the solder must flow properly so that it can be removed. For small components such as resistors, signal diodes, low power transistors etc, the tip is placed over the lead stub, as perpendicular to the board as possible. The solder around the lead melts instantly and then it is just a matter of a quick squeeze of the trigger to suck it away. It works so well that components will sometimes fall out of the board under the pull of gravity, occassionally even on boards with plated holes. For stubborn components on such boards it is sometimes necessary to repeat the process or give a gentle pull with some pliers before the leads come free. The solder is sucked into a chamber behind the tip which is filled with steel wool and a felt-like plug. The steel wool traps virtually all of the solder and it is very easy to dispose of. Inevitably some of the wool is thrown away with the solder but luckily replacing it is very cheap and easy – the contents of the original filter provided is identical to fine steel wool from the supermarket. The handpiece is a pistol-grip type as opposed to most soldering irons which use a pencil-style grip. As it turns out, the handpiece suits the way in which the tool is typically used, with it in one hand and the board held in the other. This is an invaluable tool for an electronics lab, saving a lot of hair-pulling when making many changes to a prototype circuit. • www.altronics.com.au siliconchip.com.au Hot Air Rework Stations W ith the proliferation of surface mount devices, hot air rework stations are vital for today’s service industry. These combine a temperature-controlled soldering iron (usually with a fine tip) and a hot air gun with adjustable air-flow and temperature and a selection of nozzles with different shapes. Shown here is the Jaycar rework station (TS1574). Some nozzles are cylinder shapes of varying sizes while others have two or four slits arranged in a parallel or rectangular configuration, again in various sizes. These suit the pin layouts of various SMD ICs and are used to heat the IC leads directly without damaging the chip or nearby components. With a hot air rework station and some practice, desoldering a fine-pitched IC is easy. Flux paste is applied along the pins and the appropriate nozzle is installed on the air gun. The air temperature and flow are adjusted to suit the size of the IC and the thickness of the board. Then it is just a matter of gently heating the IC leads until the solder melts and the flux begins to boil. At that point (assuming it’s not glued to the board) the IC can be lifted off leaving virtually clean pads. If required, what little solder is left on the board can be picked up with more flux paste and some solder wick. The technique for soldering an IC using a hot air rework station is similar to that used with a reflow oven. A thin layer of solder paste is applied to the pads and the IC is placed on top. It is then just a matter of clamping it down (so that the airflow can’t blow it out of position) and applying heat using the same nozzle until the paste melts and flows onto the pads. The main trick in both cases is getting the air temperature and flow rate correct. Too high a temperature or too low an air speed can cause localised excessive heating on the PC board, resulting in a singed board (it smells bad!) and possibly also component damage. As with manual wave soldering, some practice is required but once you get the hang of it, the procedure becomes routine. The Jaycar TS1574 station is supplied with three nozzles; eleven types are sold as accessories. They also stock four different types of tip for the integrated soldering iron. • www.jaycar.com.au Hakko FX888 Hakko FX951 Hakko FR803B General purpose soldering iron Advanced lead-free soldering iron Hot Air SMD Rework Station • • • • Compact Lead or lead-free solder Excellent thermal recovery With tip conical shape T18-B, cleaning sponge and wire • Heating element and tip in one • With sleep mode, auto shutdown, lock out card, quick tip replacement. Proudly distributed in Australia by HK Wentworth Pty Ltd siliconchip.com.au • Digital station with 3 steps temp profiles • Vacuum pickup • Adjustable 100o-450oC • Optional stand, pre heater and vice www.hakko.com Ph: 02 9938 1566 sales<at>hkwentworth.com.au December 2010  17 ChipQuik SMD Removal Kit S urface mount ICs can generally be removed without special tools. One technique involves applying solder generously to each row of pins, then heating each in turn with a hot iron. Eventually enough of the solder stays molten that the IC can be lifted off the board. The solder left behind on the board can then be removed with a vacuum tool and some solder wick. The problem is that this is very messy and it risks damage to both the board and IC from excessive heat. It is especially difficult if other components are mounted right next to the IC. Because the solder tends to “bead” at high temperatures you have to use a lot of it. Now there is a better solution. “ChipQuik” makes it much easier to remove surface mount ICs (or other multi-pin devices) with a standard soldering iron. It also works with some through-hole components. Essentially, the ChipQuik kit contains a special solder alloy with a low melting point and high thermal mass. It can be purchased on a reel like regular solder or in short lengths, as shown here as part of the kit. The kit also includes a syringe of no-clean flux paste and alcohol swabs. The flux paste and alcohol swabs can also be bought separately in larger quantities. The advantage of “no-clean” flux paste is that, since it is not corrosive (like some fluxes), it does not need to be cleaned off the board after use. This kit is available from Jaycar (Cat No NS3050) and Mektronics (QCSMD1). The package states that it contains enough product to desolder 8-10 ICs but the exact number will depend on just how large and how many pins the ICs have – we estimate that for hobbyists it will actually last longer than that. The technique used is similar to that descibed earlier. First flux paste is applied to the IC pins, then the ChipQuik solder is spread along them. Because it stays molten so much longer than regular solder, repeated heating is unnecessary and the overall temperature can be kept lower. Once it has been applied and heated, the IC comes off straight away. Solder wick and the supplied alcohol swabs can then be used to clean off any remaining ChipQuik or regular solder from board so that a new IC can be installed. A demonstration video can be viewed at www.youtube. com/watch?v=FTQqjggeklo This product is a good solution for those who only occasionally need to remove a surface mount IC. You would have to do so quite regularly to justify the much higher cost of a hot air rework station. If you would like to purchase ChipQuik solder in larger quantities, Mektronics sell it in “industrial pack” (CQSMD4.5) as well as the flux paste (CQSMD291AX) and a solder paste equivalent (CQSMD291SNL). • www.jaycar.com.au SC • www.mektronics.com.au Issues Getting Dog-Eared? REAL VALUE AT $14.95 PLUS P & P Keep your copies safe with these handy binders. Available Aust, only. Price: $A14.95 plus $10.00 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or ring (02) 9939 3295 and quote your credit card number. 18  Silicon Chip siliconchip.com.au