In this interview, Editor Nolan Johnson and Richard Heimsch of Super Dry preview the key criteria for component moisture management. If you can’t make it to IPC APEX EXPO, don’t worry. We’ll be bringing you interviews with the engineers, managers and technologists who are making a difference in our industry.
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Nolan Johnson: Hi, Nolan Johnson for real time with IPC APEX EXPO. And I am speaking with Richard Heimsch, director of the Americas at Super Dry. Richard, welcome.
Richard Heimsch: Thank you.
Johnson: Richard, it seems to me like there is quite a bit of ongoing interest in moisture management. Is that true?
Heimsch: It’s very true. Interest in 2021 within the electronics industry increased immeasurably as more and more people are trying to get control over their moisture sensitive devices and the management of those devices within the assembly environment. The interesting thing is that it’s often a case of you don’t know what you don’t know. And so, what questions to ask when I’m looking for a dry cabinet come up much more frequently than one might imagine. People are generally familiar with the fact that there are different levels of moisture sensitivity. The MSL is level one, two, three, four, and so forth, down to less than 24 hours from an unlimited, no control necessary. It’s imperative that the floor life exposure be known at all times in order to prevent moisture damage. That damage is in two categories. One is absorption by the encapsulant, which can crack during reflow and the other is oxidation, which significantly compromises the solderability of components that have been left in ambient atmospheres for excessive periods of time, 0.1, 5% relative humidity.
That’s the threshold at which the encapsulants stop absorbing moisture and thus the IPC/JEDEC J-STD-033 states that 5% or less you have provided unlimited, safe storage time. We also sometimes refer to that as stopping the clock and each MSL, each sensitivity level, dictates a floor life exposure time beyond which the components are not safe to be reflowed. Expired components can be dried, and the floor life can be restored, but that’s somewhat of a separate discussion from what we want to begin with here. There’s four basic questions that can be asked and you need to narrow down your identification of what kind of dry storage, what kind of safe storage do I need? First, do you wish to safely store or to reset floor life, or perhaps both? The next is how frequently do you intend to access the storage cabinet? See, it’s not the ability to get a low humidity that’s the critical performance factor.
It’s the ability to maintain the desired percentage within a working environment. The most powerful dehumidifier, most powerful dry storage may or may not be necessary. The more frequently you need to access the cabinet, the more powerful you need the dehumidification capability to be so that the recovery time back to the desired less than 5% level is not excessive. Then there’s long term storage, which typically requires less than once a week or even once a month access. That kind of infrequent access means that a powerful, fast recovery time is not necessary. There’s no need to invest in a very powerful, dry storage solution. Long-term storage has a couple of categories. Some can be the traditional, like military automotive avionic, where storage needs to take place beyond the manufacturing component, and manufacturers recommended handling lifetimes. Three years, five years, 10 years, 15 years. Even more common and consumer-type products that manufacturers are facing that issue because they’re being forced to buy forward quantities of components for a couple of different reasons.
One is the relatively short product life cycle, which can easily mean that we’re onto our next generation of product, but I have to support the old one and component availability, that’s its own topic today. For those reasons, what we might refer to as medium term storage, is increasingly required. In both cases, infrequent access of the cabinet dictates that you don’t need a highly sophisticated, highly powerful dehumidification capability and that keeps you priced down. As you move up into hourly or more than hourly, then you need to be able to have recovery time. So, the third question is how much storage volume do you require?
In some cases, simple bench stop enclosure is more than enough. In other cases, walk in room. And so, the sizing, the storage capability for the correct volume or the necessary volume of parts that are being managed would be question number three. And the last one is a newer question, a new horizon: more focus in the last few years and that’s whether or not you require climate data traceability and/or network compatibility, which any industry 4.0 situation would call for? So, summarizing, do you wish to safely store or reset floor life, or both? Because there are products that can do both. How frequently do you need to access the store cabinet? And that dictates your necessary recovery time. How much storage volume do you require and whether or not you’re looking for climate data traceability or network compatibility. Answers to those questions will significantly narrow down your range of choices. And in some cases, it can save you quite a bit on your investment.
Johnson: Quite a number of things to balance there.
Heimsch: Particularly around access frequency. That’s more significant perhaps than any of the other.
Johnson: Richard, I look forward to seeing you in San Diego.
Heimsch: Okay, great. Me too.
Johnson: Once again, I’ve been speaking with Richard Heimsch, director of the Americas for Super Dry, and thanks for listening.