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www.us-tech.com
July, 2022
Dispose Less — Rework, Repair, Reuse More
By Luca Conte, Market Development Manager — Southern Europe, Weller Tools
still affecting the market globally. Many buy- ers are also becoming aware of the need to repair and recycle electronics appliances and components to reduce waste and the result- ing damaging effects on the environment. Rework today is increasingly complex,
T
with miniature components and heavy ther- mal boards, as well as lead-free solders add further challenges. Therefore, it is crucial to have all elements needed to perform the rework procedure and eliminate risks to crit- ical solder joints.
Manual Tools Rework can be handled differently,
depending on the component, operator skill and preferences, and which tools are avail- able. Few applications require just a solder- ing iron with the appropriate tip. For those that do, “GW” tips often are used to remove short circuits or chisel tips to desolder pas- sives (from the side) in a safer way than the ‘old school’ desolder braid/weak, which is still available and in use. However, if you need to desolder a dual
line component, consider using a desoldering thermal tweezers that simultaneously heats both sides, allowing for fast desoldering of small and medium dual inline components. Weller’s thermal tweezers, WXMT and WMRT, and their desoldering heads are also available in military standard version, if needed. A sensible recommendation here is to
add enough soldering alloy on the contact surface to enhance heat transfer with all the parts involved. For most operators, this is the quickest, easiest and most convenient way to desolder chips and other surface mount devices (SMDs) with leads on two sides. Some may still have a preference for the use of hot air as a rework tool and also a small/medium size hot air pencil, rather than a high-power airflow gun.
Proper airflow is critical as rework can generate harmful fumes.
an accessory, with the footswitch) to turn it on/off. There also is an option to set a ther- mal profile consisting of temperature, airflow and time for each phase up to five. WHA3000P adds the vacuum feature, so
after desoldering a component it is possible to remove it automatically. Also, in this case, the user can run a thermal profile of three steps, including the needed preheating tem- perature (that can be connected to the unit). It also includes the option of connecting a thermal sensor to study thermal profiles.
Preheating Recommended Preheating is recommended in all cases,
and even mandatory in some. If you cannot
he rework of applications has increased drastically over recent years, exacer- bated by the shortage of components
High-Power Hot Air For four-sided and “leadless” compo-
nents (QFP, QFN, BGA, etc.) the most effi- cient solution is hot air. Typically for such components, especially the larger ones, a high-power hot air gun is required, and in Weller’s portfolio there are two different solutions available: WTHA1 and WHA3000. Both are digital, standalone units with a built-in pump. WHA3000 is also available with a Venturi valve if nitrogen or com- pressed air is desired. WTHA1 works by set- ting the temperature and flow, and simply pressing a switch (or button on the unit or as
work at high preheat temperatures for vari- ous reasons, even a low temperature will lead to an improvement. For the rest, Weller’s heating plates, as well as the rest of the range, are known for precision and relia- bility. On the WHP1000 and WHP3000, there is the option to use a connectable ther- mal sensor as a “system pilot” (the tempera- ture set on the plate will be the target point on the sensor) as well as the possibility to use all of the ceramic heaters, or just a part of them.
Weller’s complete rework systems
WHA3000PS and WQB4000SOPS are sup- plied with preheating plates. The first one is the set consisting of WHA3000P with a pre- heating plate and circuit and hot air gun holder. WQB4000SOPS is a semi automatic rework system with a “split optic positioning system” that enables component alignment before soldering by seeing both circuit pads and component leads (also for QFNs and BGAs) on the same image. With its precision, power and easy-to-use eight-phase thermal profiler, WQB4000SOPS is the choice of dif- ferent military and EMS companies.
Plated Through-Holes Plated through-holes (PTHs) are anoth-
er area of interest. Because of that, Weller launched a high-power desoldering iron that is available in three different versions: ergonomic DSX120 and WXDP120 and “ver- tical” WXDV12’ for applications with limited access. These desoldering irons are the most efficient, precise and safest on the market and include numerous features such as 120W power, good contact surface between nozzle and heater, and long-tailed nozzles that drive soldering alloys to the collector in hot condi- tions without cooling down. This can eliminate the alloys solidifying
and clogging the duct before reaching the col- lector. It is important to choose the correct nozzle: its hole must be as similar as possible to the hole on the PCB. In this type of applica- tion, maintenance of the units and tools is key. Continued on next page
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