The NPI engineer should be paying close attention to the following three areas (based on the assumption that a typical lead-free alloy with a melting point of 217 degrees Celsius (☌) is used): However, certain component requirements may require them to work at the upper or lower limits of these tolerances. Where possible, the EMS provider will try and achieve a result in the middle of these tolerance bands. And this is where the first real analysis of the profile begins.Įach solder paste manufacturer will recommend a baseline profile with + and - tolerances. Once the PCBA has passed through the oven, the results from the data logger will be downloaded into the chosen oven profiling software. It's important that that the data logger is positioned correctly so that it doesn't affect the movement of the PCBA through the oven. The PCBA will then be run through the reflow oven with thermocouples attached to a data logger. But this can be a destructive process so will require a sample PCBA from the outset. For the best results, a thermocouple should be placed underneath the device which makes direct contact with the terminations and enabling a small hole to be drilled through the underside of the board. Special attention should be given to BGAs. An adhesive, such as Chipbonder, ensuring residual glue is not found between mating surfaces.High temperature solder to secure the thermocouple to the component lead.Quite often EMS providers will tape these in place but, unfortunately, there is a risk that they will lift during the process, which can result in the air temperature being measured rather than the board and lead temperature.įor a secure connection we recommend applying: a transformer, Ball Grid Array (BGA) and passive devices.ĭependent on the size of the PCBA, it is recommended that between three and six thermocouples are attached and it's critical they are connected properly. These should be attached to a range of components with varying degrees of heat dissipation - i.e. The NPI engineer will attach thermocouples to multiple locations across the sample board. If one isn't provided, then the NPI engineer may request one for use during the set-up process. Ideally, the OEM will have provided their assembly partner with a populated printed circuit assembly.
Using their skill, judgement and experience, the NPI engineer will select the profile and temperature settings that they believe are best suited to the new assembly. One dedicated to assemblies that contain sensitive parts and require lower temperatures.One dedicated to densely populated assemblies with elevated temperatures.The time taken to perfect the baseline profile will pay dividends as most assemblies will then fall within one of them. Over time, some EMS providers may develop a range of "baseline" profiles, which can then be selected depending on the PCBA they are working on. The New Product Introduction ( NPI) engineer will usually start the process by selecting an oven profile they have used before and that is stored on their system. So what should your EMS partner be doing to perfect their reflow oven profile? Let's find out. If you fail to profile the oven correctly, then all of the hard work and effort that has gone into loading feeders, programming the machines, optimising the build and then running the production line will be wasted. The reflow oven is used primarily for the reflow soldering of surface mount electronic components to printed circuit boards (PCB). There is however one specific step that can make all of the difference when it comes to quality and consistency - creating the surface mount (SMT) reflow oven profile. But, broadly speaking, the process steps that they go through to produce PCBAs are the same. But consistently producing them in volume can take time to perfect.Įlectronics manufacturing services (EMS) providers may well have their own preferences when it comes to their choice of machine type and brand. Printed Circuit Board Assemblies ( PCBAs) are often viewed as commodity items.
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