Small details make the big difference

Bernhard Martin, President, Munich/Germany

The rework procedures of advanced packages such as ball-grid arrays (BGAs), chip-scale packages (CSPs), other field-array types and tiny chip components or delicate fine-pitch ICs, are every so often not even complicated, but also need relatively high investments in equipment and operator training. However, even very fragile ”fly-type” components, advanced and other sophisticated packages can be comfortably and securely processed – without gigantic investments. To resolve this task, rework technology specialist firm Martin has engineered innovative upgrades of its Expert-04 series. With three dedicated equipment versions, based on the same proven platform, all rework jobs can be performed in an optimum environment under optimum conditions. These ”small” Eco Expert rework units provide virtually the same performance as the large Martin stations do. The trade-off is made with a lower level of automation (nevertheless it’s semi-automatic and can even be programmed by PC or manually). All requirements for high-quality and reliable board assembly rework according to IPC-A-610C can be fulfilled. Sailing in stormy waters, as the global electronics manufacturing community does at the moment, this three-fold, low-cost solutions helps to leave some money on the table too.

The ”small” Eco Expert-04 series is compact and reasonably priced, and at the same time is easy-to-use because of its skillfully designed concept. In this it follows the Martin engineering principles: our products have to be as simple as possible, but also have to offer the user very effective and innovative solutions which are basically capable of avoiding all potential sources of errors. This low-cost equipment is available in three different versions for requirements of up to mid-range throughput rates. It is clear proof that in the rework area outstanding economical solutions can be realized for the benefit of users drawing on innovative ideas. Trained operators may be able to perform up to 80 complete component exchange procedures with very high accuracy and reliability per work shift.

The steps of component replacement are known in principle: desoldering of the old part, then soldering the new; whereas in intermediate steps used excess solder must be removed and then the remaining solder be refreshed manually by applying flux with a pen. Desoldering/soldering with the Martin technology is performed by a directly pointed stream of hot air onto the component. Additionally, this area of the board assembly is heated up from the underside by IR radiation. The stream of hot air is exactly monitored and controlled in temperature and amount of flow, resulting in very high soldering precision.

The Eco Expert now features an entirely new positioning arm to support the desoldering and soldering steps. This highly accurate arm is moving in the XYZ and D (rotation) axis, and will be put on the worktable of the soldering station by its magnetic base. In contrast to the predecessor’s construction, it features an automated desoldering function, reducing manual interactions of operators. The components are desoldered/soldered in a way that offers highest possible caution to the assembly, and no pads or copper tracks get broken.

This should be the highest and foremost objective of any rework action: avoiding any possible defect on parts or boards during the procedure. This in turn needs that the equipment must not add sources for repair-induced defects as a prerequisite. The positioning arm fulfills this demand, since only when the solder is molten will the component smoothly and carefully be lifted automatically without any operator action. Likewise, in a secure and precise manner, the part will be placed and soldered later on the assembly.

For the placement of surface-mount devices utilizing the positioning arm, there are various proven tools available. These are for example the Star Tools which have a star-like contour. They allowa quick and accurate manual placement of CSPs without any further sophisticated actions. Under normal conditions, users need only a small collection of about four different standard Star Tools for their daily work. This way the tools don’t have to be exchanged frequently. In total, there are about 40 different Star Tools available for virtually all CSP types, covering every potential application. Just in case a user needs another custom-specific tool, this can be provided within 10 days. On the other hand, BGAs and microBGAs are positioned by other tools that embrace the devices tightly. And QFPs or similar flat packages as well as tiny microSMDS are handled by proven vacuum pipette technique. From this it becomes clear that we have competently engineered an optimum product for every rework task.

The star-like outline of the Star Tools (patent pending), which is snap-in mounted in the placement arm, provides for easy and exact manual adjustment of the component consistent with the pad structure on the PCB. During the adjustment, the PCB geometry or pads are visible through the symmetrical cuttings or the edge openings, respectively, and therefore provide unmistakable placement targets. This way they deliver accurate reference points for the component adjustment. The Star Tool is simply snap-in mounted in a placement tool, and this in turn is put into the positioning arm, fixed through magnetic force. The arm which has mechanically saved the before taught position can then easily and safely place the component. The Star Tools are inexpensive, and provide a very exact method for the replacement of advanced packages such as CSPs. For more than two years, the tools are now in use worldwide by our customers in the Martin rework stations in both the ”small” Expert-04 series (the predecessor of Eco Expert-04) and the top-of-the-range Expert-06.

Another important innovation of the soldering tool is provided through the ongoing engineering of the hot-air nozzles used to direct the air stream. Though these nozzles had a very reduced inner diameter in the past, in order to blow the hot air in a lance-type shape onto the component, now the diameters have been widened a bit to form trumpets. This broadened stream of hot air helps to avoid too high temperature peaks at the solder joints. Despite its increase in diameter, the stream of hot air can be exactly directed even on very tiny chip components, so they can very carefully be soldered. Especially for rework using the very small ”fly”components such as the 0402s or 0201-parts, the resulting reliability of the procedure is even higher now. In the newly designed trumpet nozzles, a vacuum pipette is integrated to pick the componen. This detail helps to reduce the desoldering procedures by trial-and-error steps, since the component keeps its temperature during desoldering, and can then be lifted and taken away troublefree. Vice versa, for the soldering the part is exactly seized, and will be placed quickly on the solder pads without any further operator action.

Our focus is also set on high reliability of monitoring and controlling of the air temperature. Highly accurate temperature sensors are being used in the soldering stations which are calibrated utilizing a temperature standard during manufacture. The sensors are offering the highest possible accuracy of those devices supplied from the market, and are by far superior to the commonly used K-types. This technology assures that a preprogrammed air temperature is maintained under all circumstances and doesn’t float, simply showing ”house numbers”. Again, on this highly precise air-temperature control technology, the Martin company is granted a patent.

Since we all know definitely that lead-free processing will soon become a mainstream on the shop floor, the exact control of the soldering temperature is a very important issue. The basically higher soldering temperature (about 30K more) for the modified soldering alloys can lead to a situation where not absolutely tightly monitored and controlled temperatures may reach an area of damage for both board and components, especially as far as plastics are concerned. But possible damage is not restricted to those materials only. Excessive temperature can induce the beginning of defects which show up some months later in the field, creating a lot of trouble and expenses. Therefore, an effective and reliable method of temperature control is of ultimate importance. The ”small” Eco Expert-04 features such a valuable technology, a unique quality in its investment category. Because of exactly controlled operating temperature, the heat can go up stepwise in small plateaus within a very short time. This function delivers the capability of customized reflow profiles for desoldering and soldering, and programming of various pre-heating and cooling cycles.

The Eco Expert-04 series consists, as mentioned, of three different versions which cover the complete range of rework applications. The top-o-the-range model Expert-04S (like superior) addresses general-purpose applications, reworking with all kinds of parts such as chip devices, PLCCs, QFPs, BGAs, CSPs and many more. The version Expert-04H is designed for the repair of smaller board assemblies which are used especially in telecom gear such as cell phones or in other similar miniature and sophisticated mobile electronic appliances. The model Expert-04J (jet) is an easy-to-use SMT soldering station for very fast and troublefree rework with fly or chip components in the manufacturing line and the lab alike. Its IR underside heating speeds up the process remarkably. For such rework to be provided easily und quickly, every user will need to have this done as simply as possible, but at the same time with very high precision, and to avoid any possible damage of soldering objects.

It is the details that are most difficult in rework. That’s the reason why the Martin company carefully examines all the ideas or suggestions from the practical side, in order to provide its customers with value-added application benefits. Take, for example, the fact that operators want to be more independent from the handling of equipment in their work flow, but always have to divide their attention when they put back the soldering tool into its holder, or when they have to take it out. Now, after the redesign, the hot-air soldering tool can be very easily – without spending too much attention on it – put down in its holding device where it will then automatically self-center and be securely kept. Moreover, this holder or stand features an auto-start function which activates the hot-air heating as soon as the tool is taken out. Such an almost unnoticed detail offers advantages: first, there is no manual heating switch needed, which has to be activated every time; second, because the heating starts immediately, the time to which the tool can solder a component is further shortened.

With these kinds of details which are frequently not observed (but in daily work are very valuable), we just want to give an idea about how we continually pay attention to the ongoing engineering of our equipment. We are pleased only when a highly practical handling of critical rework procedures is attained, which must be, at the same time, comfortable and perform with high reliability. We put a lot of effort in on the fact that operators can focus on the task itself to perform it with excellence, and not having to deal with a wealth of confusing functions in order to do so. And it should be noted that our rework products are designed with cost-efficiency in mind, since those solutions also have to be affordable.

Board width max. 400mm

Board length max. 500mm

Air flow throughput 1 to 25l/min ±1%

Air temperature 150 to 400°C ±3% repeatability

(Temperature control by high-precision sensor)

IR underside heating 20 to 120W (versions H/J)

50 to 500W (version S)

IR radiation element size 40 x 33mm (versions H/J)

130 x 105mm (version S)

Data memory 100 complete soldering programs

Dispensing volume 0.01 up to 10mm3

(temperature compensation integrated)

Dispensing media water, solder paste

Reparatur in der Elektronikfertigung ist nicht der heißersehnte Schritt im Prozeßablauf der hochvolumigen Serienproduktion. Trotz qualitätssichernder Maßnahmen mit 6-Sigma bzw. statistischer Prozeßkontrolle (SPC) lassen sich Fertigungsfehler nicht vermeiden. Wichtig ist, mit optimalen Systemen sicher und effizient Ball-Grid-Arrays (BGAs), Chip-Scale-Packages (CSPs), andere Advanced-Packages sowie Chip-Bauteile auf Baugruppen auszutauschen.

La réparation dans la fabrication électronique n’est pas une phase des plus appréciées dans le cadre de la production en grande série. Malgré des mesures d’assurance qualité avec 6-Sigma ou le contrôle statistique des processus (SPC), les défauts de fabrication sont inévitables. Il est important de remplacer de manière sûre et efficace les ball-grid-arrays (BGA), les chip-scale-packages (CSP), les autres advanced-packages de même que les puces sur les cartes à l’aide de systèmes optimisés.

La riparazione nelle linee di produzione di componenti elettronici non è poi un passo ardentemente desiderato nei processi di produzione di serie. Nonostante le misure adottate per la sicurezza della qualità tramite Sigma 6 ovvero controllo statistico dei processi (SPC), non è possibile evitare errori di produzione. È molto importante scambiare i Ball-Grid-Arrays (BGAs), Chip-Scale-Packages (CSPs), altri Advanced-Packages nonché componenti chip sui gruppi di costruzione con sicurezza ed in modo efficace tramite sistemi ottimali.