![]() And so, we get a specification for a solder paste or a component, where we're concerned about heating or cooling too fast or, like, warping a BGA or cracking capacitor or something like that. The idea is, when I'm calculating the slope over what interval, and typically we're talking about the minimum interval that we're looking at. It is one that we've dealt with for many, many years and it has never been answered successfully to my satisfaction. So, I will call it "slope", and it is the rate at which temperature changes over time. Having worked for a Dutch company, we had this problem, and the word "gradient" in Europe typically means what we call a slope or ramp rate in this country. Gradient is not a word that we typically use in the United States, and it can often be confusing. The first thing we have to note is that this comment comes from Germany and we have to note the use of the word "gradient". A lot of times we'll see, particularly with some of the lead-free solder pastes, where slope is extremely critical, and actually under that three-degree-centigrade-per-second, too. This is important because a lot of things will be gradient- or slope-dependent. He points out that, if he calculates it over a 10-second interval, he gets a gradient of 3.5 degrees per second, but if he calculates it over a 20-second interval, he gets a 2.8 degrees per second gradient. We'll talk a little bit about how compatible that may or may not be, but the question is, basically, what's the right way here? How's it being calculated. JEDEC specifies a ramp-up, but it extremely depends on the chosen time span. Is there any specification or empirical value for the time period the gradient is calculated in, one second, ten seconds, etc. The question for today - I have a question concerning the gradient for reflow profiles. We're here to talk about service-bound processes and equipment materials and procedures. This is Phil Zarro and Jim Hall of ITM Consulting, sometimes known to many in the industry as the Assembly Brothers, Pick and Place. He is a pioneer in the science of reflow. He has vast experience in SMT equipment, materials and processes.Ī Lean Six-Sigma Master Blackbelt, Jim has a wealth of knowledge in soldering, thermal technology, equipment and process basics. With over 35 years experience in PCB assembly, Phil is one of the leading experts in SMT process failure analysis. Process Troubleshooting, Failure Analysis, Process Audits, Process Set-upĬEM Selection/Qualification, SMT Training/Seminars, Legal Disputes ![]() Is there a specification for the time period to calculate the slope for a reflow oven profile?īoard Talk Board Talk is presented by Phil Zarrow and Jim Hall of ITM Consulting. Slope Calculation for Reflow Oven Profiles To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video.
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