Flux becomes increasingly tenacious the longer it sits on the board.
This month our topic is not so much a defect as something to consider when running environmental tests before any destructive analysis on solder joints. The through-hole joints shown in FIGURES 1 and 2 were soldered with a high-temperature alloy as part of our trials on robotic laser and single point soldering. The amount of flux in high-temperature cored wire tends to be higher, hence more residues after soldering. If sample boards will be exposed to high-temperature storage, in this case 200°C for 1,000 hr., or temperature cycling, clean the residues first. It is much more difficult to clean after this level of aging, and mounting samples in epoxy for microsections is much more difficult.
Many “topical” conferences are not just good at answering questions, but they also open one’s eyes to questions that have yet to be resolved.
The ITI/IPC 2019 Conference on Emerging & Critical Environmental Product Requirements is a perfect example. The two organizations caravanned across the US in June, bringing scores of environmentally conscious engineers and compliance officers up to date on the latest REACH and related regulations in the EU, UK and Asia.
What distinguishes REACH from almost any chemical safety regulation I can think of – including RoHS – is parties need to prove the safety of a substance before it’s allowed on the market, and exemptions must be justified from both a risk point-of-view and a socio-economic point-of-view. Multiple independent technical committees, appointed by the Member States, make those assessments.
As the challenges of training evolve, so does the definition of lean.
An organization cannot become lean without tons of training.
Think about that oxymoron for a moment. It takes time to train, time that a lean organization cannot sacrifice. Training in this industry, which utilizes many varying yet intertwined processes, has traditionally taken the form of on-the-job training (OJT) versus a formal, classroom-style format. In any organization, especially a lean one, OJT is much easier to administrate and far less disruptive to employees and production than other types of training. In a service industry, even in support positions off the shop floor, it is much easier to take someone offline and plunk them down for formal training. In a lean manufacturing environment, however, excess resources in any given job function or department are rare. Hence, most training is integrated into the daily workflow as OJT.
It’s adding unnecessary costs to your supply chain.
Want a more robust and cost-effective supply chain? Shrink it. Remove the expensive middleman. You don’t need to pay a PCB broker a 20 to 40% markup to, basically, relay information from you to overseas vendors.
The truth is the PCB broker business model – where companies buy printed circuit boards from an overseas manufacturer and then resell them to a customer – is outdated. And it’s adding unnecessary costs to your supply chain.
Years ago, brokers were small operations, with perhaps three to five people. And at one time, they did provide a valuable service to their customers, offering lower prices on boards made overseas, while handling all the details of procurement from foreign vendors in what was often a challenging PCB buying cycle.
Inappropriately sized pads can result in excessive solder and, eventually, defects.
This month we show soldering of 01005 chip resistors from an early project with lead-free assembly. The microsection image in FIGURE 1 shows a few issues, but it’s the circles in both joints that caught my eye. Yes, they are voids before they are unmasked. During sectioning we stopped just before entering the void. Most would have continued a few more micros to remove the thin sliver of solder, which was the wall of the void, to show the void. But everyone has seen voids before!
When commercial AOIs were not up to the task, a little internal ingenuity saved the day.
While there is great debate in the quality community as to who first made the observation that visual inspection by humans is not 100% effective (both W. Edwards Deming and Dr. Joseph M. Juran have been given credit) and even some debate about the true effectiveness rate (is it 75%? 80%? 85%?), all agree it is inefficient and error-prone. Yet, automated optical inspection is often deemed not cost-effective for relatively simple processes in many factories.
One area that is often problematic for electronics manufacturing services providers is odd-form part through-hole insertion. Through-hole odd-form parts continue to be used when a part’s weight or need for a more robust solder joint makes that level of interconnection more reliable. Transformers, large capacitors, diodes, relays, connectors and pressure sensors are few examples of parts that are often still packaged as through-hole. Manual assembly, like manual inspection, is prone to variation and associated defects, particularly issues such as misaligned parts, missing parts or wrong parts. Odd-form parts are typically of a size or shape that makes automated insertion methods impractical.