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Rework – easier than ever

Easy hot-air soldering and desoldering without a problem
Rework – easier than ever

More and more of highly packed SMT boards are subjects for repair They require of course easy and effective solutions that will enable a greater flexibility, without loosing time for selecting equipment or adapting spe-cial parts to an existing gear. The Spainish company JBC has come up with a complete product range of soldering and desoldering devices – based on knowledge of almost 70 years in this area.

Jochen Stenz, Industrias JBC, Barcelona, Spain

Most board manufacturers have highly efficient production lines where an error rate of less than 3% is achieved. Instead of installing relatively expensive rework equipment, it is cheaper for them to throw the faulty boards away. This makes clear that there is still a requirement for equipment, particularly where high-value boards are produced, for example in aviation or medical areas, etc. Therefore, highly reliable rework equipment is necessary which will enable the operator to repair or rework, respectively, the SMT boards without damaging the PCB or surface mount parts.
No damage at desoldering
The problem occurring in the process of desoldering is that, usually, for the re-moval of a component, some kind of physical force needs to be applied. Trying to remove a component without the solder being totally fluid, there is a great danger of taking the pad off as well. There is a great variety of ways for desoldering SMDs – some complicated, some not, but all are very costly if it gets to covering every type of component. Contact-free SMT repair can be clumsy and often causes damage to other components on the board which could be avoided by some type of protection.
The JBC JT 6040 is a hot-airflow station which is easy to use and makes it almost impossible to do any damage to a circuit board. Temperature can be adjusted from 150 to 450°C, airflow from 6 to 34 l/min. The specific features of the station are the extractors and protectors, rectangular shaped bowls with spring loaded vacuum cups mounted over the center. After having applied some flux to the solder joints, these extractors are placed over the component to be desoldered. The hot air is then concentrated onto the component while the surrounding area is perfectly protected from the heat. Only when the solder is totally liquid, the component is gently lifted-off the board. For smaller components, the protectors with a spring-loaded tripod can be used. Ideal for removing ICs, the station equally well serves for removal, or even the soldering of other components. The removal of a medium-sized IC takes aproximately 20s. Buttons on the front panel start the vacuum pump and hot air flow, although the hot air should be controlled by a foot pedal delivered with the station. As soon as the foot is removed from the pedal, the air flow will continue for a short period without the heating element switched on to cool the handpiece down.
Even though there is a wide range of additional special size protectors and extractors available, the 5 protectors and 5 extractors provided with the station cover most needs. The control unit has a 700W heater, internal vacuum pump and comes with heater stand, control pedal and other accessories as filters and spare parts. As a valuable addition to the hot-air desoldering station, JBC is able to offer pliers.
Cleaning and desoldering of through-hole boards
After having removed any type of SMD, the operator has to clean the pads of the remaining solder. The most common way to do so is with a desoldering iron. It is imperative to have good heat transfer and suction. It also helps to apply some flux on the solder that is to be removed. The JBC desoldering iron enables the user to activate the vacuum via a push-button on the handpiece. A vacuum-pump is included in the unit. The desoldering iron itself has a power of 75W and enables a variation of the temperature between 100 and 400°C. The user can choose from a variety of different sized screw-on tips, which are either long-life, or of high thermal transmission.
The desoldering of through-hole boards is just as easy: The different tips adapt to the most common lead-sizes, and the suction capacity of aproximately 6l/min with the rapid heat-transfer means that the melted tin vanishes almost immediately. The solder tin is collected in a barrel connected to the iron. The vacuum hose and pump are protected by paper filters from tin and flux particles.
Soldering temperature not to be exceed
As it comes to soldering, we get to the core. Especially in rework and repair, soldering irons tend to burn-out their tips because most of the time the iron is left under high power in the stand. This is because the user requires the iron always to be ready. Quick and easy tip exchange as well as high flexibility are characteristics that are highly desirable in the rework area and hardly fulfilled by any supplier of soldering irons. Changing from small to large solder joints requires tip exchange, making life difficult for the repair person. The user encounters the problems of little flexibility, slow tip exchange, and burning-out of tips.
To solve those problems, JBC has developed an advanced soldering station. The soldering gear basically consists of a 75W control unit, and depending on the requirements, either a 20W iron for high-preci-sion work, or a 50W iron for general soldering can be connected. Either of the irons are very light and feature a pencil-like shape. They are easily connected and disconnected. Additional flexibility is achieved by the very short tip-change: The iron stand contains a cartridge extractor where the old one merely has to be pulled-off and the new one to be inserted. This easy tip-exchange gives further flexibility. More than 30 cartridges provide the possibility to work on any type of solder joint.
Two important features avoid the burning-out of tips: First, the maximum temperature is 350°C, a temperature that does not need to be exceeded for soldering work on SMDs; second, a sleep-function which reduces the temperature at the tip when the handpiece is placed in its stand. This function is in no way disturbing to the user because the extremely quick heat-up time of aproximately 2s for the small and 5s for the big handpiece lets the tip reach working temperature before the user gets to the solder joint. Other soldering irons are not able to achieve such a remarkable short time and accurate tip temperature. This is because the tip and the heating element is a single unit. This avoids heat discipation and loss and delivers the heat directly where it is required – in the tip. The often stated disadvantage of higher costs in this context is not true. Our experience shows that a cartridge can last 5 to 10times longer than a „normal“ tip. The heating element is very resistant and durable. Beside the sleep-function, the operator can choose an additional method to save the tip’s life. The tip extractor can also serve as an optional stand in which the power is completely shut-off as soon as it is being touched by handpiece or cartridge. Through-hole components can be soldered easily – the high heat capacity supports fluid soldering. Precision work on high-density PCBs, as it is often the case in the repair environment, does not present a problem. The amazingly short distance between handle and tip makes it highly managable and flexible to enter confined areas. The handpiece has a ergonomical design and does not get hot. For the station pliers are available. The pliers work with the same cartridges as the 50W iron and support easy desoldering and soldering of a whole lot of different SMDs. To give the gear the highest flexibility in soldering while maintaining the advantage of quick tip-exchange, in the pliers the cartridges are fixed by screws.
Fax +34-3-424-9301
Bei den immer häufiger eingesetzten Advanced Package-Bausteinen, beispielsweise Flip-Chip, BGA oder Chip-Scale-ICs, ist der Reparaturprozeß sehr kritisch geworden. War bereits bei Fine-Pitch-ICs herkšmmlicher Bauart manuelles Läten bzw. Entlöten nicht einfach, so verschärft sich die Prozedur mit den noch kleineren und anspruchsvolleren Gehäusen weiter
Le processus de réparation avec les composants „Advanced Package“, de plus en plus souvent utilisés, comme les Flip-Chip, BGA ou Chip-Scale-Ics, est devenu très critique. Si le soudage et le dessoudage manuels étaient déjà difficiles avec les CI Fine-Pitch conventionnels, ils le sont davantage avec des boîtiers encore plus petits et délicats. Mais les utilisateurs ont à leur disposition un nombre toujours croissant de solutions.
Nei componenti modulari Advanced Package sempre più frequentemente applicati, come per esempio Flip-Chip, BGA oChip-Scale-ICs, il procedimento di riparazione è diventato molto critico. Se in un Fine-Pitch-ICs di tradizionale tipologia era già difficile eseguire una saldatura o dissaldatura manuale, ora il procedimento è ancora più intenso per via degli involucri ancora più piccoli e più sofisticati. Gli utenti possono tuttavia scegliere una gamma di soluzioni sempre più ampia.
EPP 248
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