And on top of that these tin-lead components may not withstand higher peak temperatures. Such a solder paste may not withstand higher peak temperatures and may cause dewetted and open solder joints if high peak temperatures are used. Also keep in mind that in backward compatibility you are using tin-lead solder paste since most of the components on the board are tin-lead. If the tin-lead profile with maximum peak temperature of 220C is used, the BGA balls will not reflow at all or will partially reflow, creating a serious solder joint reliability. The real problem arises when using lead free BGAs on a primarily tin-lead board. In a backward compatibility scenario, it is not a serious issue when using leaded components such as SOIC, PLCC or fine pitch with lead free surface finishes on a primarily tin-lead board. In such as case the profile must accommodate both tin-lead and lead free package requirements. The problem can be further compounded by backward compatibility issues where some lead free components have to be used on a primarily tin-lead board. Even when the failures are found, they will keep on building boards using the same profiles and blame the failures on their suppliers or the designers instead. Such a guess work would not be so bad if they went back and checked the profiles using some failed boards because there are plenty of failed boards in such companies. They tend to guess the thermal mass of the board and use guess the oven settings that may work. For example, many companies do not even bother with using loaded board attached with thermocouples. However, this easy task is rarely performed by many companies. In case of BGAs, thermocouples need to be attached to the inner and outer rows of the balls as well.Ĭommercial hardware and software packages, such as MOLE, data pack and many others are available to make thermal profile development an easy task. With this tighter process window the importance of using product specific profile is becomes even more critical.įor developing the profile, you need the loaded board with six to eight thermocouples soldered to solder joints of large and small components across the board. This reflow process window narrows to 15C since the soldering needs to be done between 230C to 245C. So I would fully expect having to heat the board more than what the profile says.With tin lead eutectic composition one could easily get away by maintaining peak temperature between 190C to 225C, a variation of almost 35C and still achieve good reflow soldering results. And unlike in an oven, where you have fairly insulated environment with little/no drafts and heating is done from multiple directions, with a hotplate you are heating only from the bottom - and the component leads/pins may not be hot enough yet, resulting in a cold joint, despite the paste having melted already. You don't care only that the paste melts but also that it properly wets the surfaces it is supposed to join. I was just hoping to know that before hand. From that perspective the datasheet is applicable and 1:1 hot plate vs reflow oven. Some experimentation found that the solder paste melted nearly at the exact temperature of the melting point in the chart above. People do this even with kitchen skillets with no temperature control at all. RF, PLC, CAD, HW Startups, Robotics, Microcomputing, DIY Audio, DIY Gear, DIY, Mindstorms, ASM, EE Books, Product Design, LabVIEW, Breadboard, RTLSDR, Manufacturing, Electronic Circuits.Ī hot plate definitely has temperature control within 10 degrees.ĭepends, you didn't say what kind you have. AskElectronics, Electronics, ECE, RPi, NiceChips, DevKit, Arduino, micro:bit, Nucleo, STM32F4, MSP430, PSoC, ARM, Amp Hour, FPGA, DSP,.How to solder: SMD Resistors, SMD ICs, SMD QFP IC, SMD Drag Solder, SMD Tips, 1980 Soldering Videos.Gerbv, GerberLogix, DFM Now, ViewMate, ZofzPCB, GC-Prevue. Pro ($$$$): Altium, Allegro, OrCAD, PADS, Xpedition.
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