The method for attachment for flip chips is similar to that of BGAs. If you want to be absolutely certain of your joint reflow temperature you need to physically make contact thus drilling a hole. Currently RIT is conducting a very extensive study on “in-direct” methods of attachment, where one can use an off-set for example from thermocouples attached externally to the component. I’ve seen some of the preliminary data and it looks very promising, thought the study is focusing specifically on BGAs. The benefit of course is this is non destructive. This study should be completed by year end at which time I will be sure to post on this website as well.

Brian

Brian

A formal study will be coming, it should be completed by year end. The size of the aluminum tape was about 1/4″ square. Kapton was not used with the aluminum tape.

Brian

Thanks, Miriam

Great question. Several years ago we (KIC) took a look at Saunder probes which I now believe are called Temprobes from ECD. Now this was many many years ago and at the time we found the attachment method to be too unstable to warrant further investigation. I came across these probes again at a customer about a year ago and do not know how old they were, but I still observed real difficulty keeping them in place. You could see them bounce around when running a live RF profile since the TC reading looked like a saw-tooth. Also I had a few contact points that were not perpendicular to the probe which made attachment nearly impossible. In the end, the operator gave up in frustration and went for aluminum tape. The idea of external probes seems like a good one, but getting everything to line up just right I am not sure how practical it is. What is your experience? How complex are your boards? I am also told if you have low clearance in your oven you can’t use them, but not sure about this. Frankly they were not considered for the RIT study since they are not widely used despite being on the market I believe for more than 10 years. Kapton tape is still king as the mostly widely used attachment method, perhaps more than ¾ of the time and what this study showed is aluminum tape performed better thermally while also having the convenience of tape that it can be “sized/cut” to the attachment area and used in just about any situation. With ever more denser boards there is not a whole lot or real estate to work with so having the ability to conform your tape to a tight spot is pretty important. Of course the downside to Kapton is it doesn’t want to stay in place also giving you that similar saw-tooth reading. If you do not have issues keeping the probes in place, I suggest you conduct your own mini-study. Compare the same contact points with more than one attachment method. For example run a TC using aluminum tape to the same contact point as the probe, of course if you connect them at the same time don’t let them touch. This is not exactly scientific but it will at least give you an idea if both attachment methods give you the same reading.

Also, I have no idea if all the mass of the temp probes comes into play with the overall thermodynamics of the board? The arm of the probe looks beefer than the wire of a TC and the hinging mechanism I wonder if it has a thermal impact? ECD, I am sure has considered this and I would assume it doesn’t have an impact, but I don’t know. Keep in mind though, the whole point is to measure your PCB with the least amount of foreign material attached, since whatever you are introducing into your production environment from TCs to even the profiler doesn’t belong there. For example, most users will trail a profiler a foot or longer behind the board as to not introduce the mass of the profiler to the production board being measured. Dick, I will be exploring further how mass plays into profiling. My gut tells me that my industry is getting a little carried away with all these tools we are introducing to make your life easier. Their mass could perhaps be causing their own problems in interfering with accurate data collection,……but I ramble…. Thanks for the question.
Brian

We have had requests for a software solution that will adjust oven set points according to the thermal load of the oven and respond to the various changing conditions. Currently, this option is not available with the KIC 24-7 software, or any of the KIC products.

However, the KIC 24-7 software will monitor your oven and issue an alarm when the conditions drift out of specification. KIC offers a software solution called “Navigator” which is available for KIC 24-7 and KIC 2000 monitoring and profiling systems. Navigator is a prediction software product that uses the database of the Profile Library, that is part of the KIC 24-7 monitoring system and KIC 2000 Profiler. Navigator may be used before the oven becomes out of specification and allows you to create set points that are in specification if your oven is loaded or unloaded. Currently, changing the set points requires that another baseline profile be ran to verify the set points are still within specification.

If enough customers request an interest in a product that adjusts set points “on the fly”, KIC would look into this request. Currently, many customer processes do not allow for KIC products to make changes in this manner.

Thanks for your post Miguel. Hope this covers your question.