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Baking components at 70 degree

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... - Dec 19, 2007 by Slavik  

We decided to bake components in tray package at 70 Degree p... - Dec 19, 2007 by Slavik  

Thank you Bubba ... - Dec 27, 2007 by davef  

#52969

Baking components at 70 degree | 19 December, 2007

#52970

Baking components at 70 degree | 19 December, 2007

We decided to bake components in tray package at 70 Degree prior soldering. I am looking for suggestion regarding baking time for MSL3 components: Up to 1.4mm package thickness 1.4-2 mm thickness 2-4.5 mm thickness In JEDEC-033B this temperature is not specified Kindly advice

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#52971

Baking components at 70 degree | 19 December, 2007

I'm inclined to suggest that you use a specified temperature, thus eliminating your situation. Why not use 90�C?

I suppose you could calculate a duration for 70 based on the requirements at 40 and 90 if you really wanted to, but still I wonder why.

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#52972

Baking components at 70 degree | 19 December, 2007

Dear Steve. We are EMS company and we are getting wide range of components from our customers. Some of them came in trays, that can withstand up to 75 degree maximum. If someone will not pay attention to this the tray get damaged (if there is some QFP's inside thy get damaged as well). We are tiered from these accidents. 90 degree and more are not recommended from soldering process of view, specially for rebake components and we have bad experience with it. Regarding calculations, I am not sure, that there is some proportional calculations between 125-90-40 degree.

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#52974

Baking components at 70 degree | 19 December, 2007

I see. You might request that those parts be provided in the proper trays (125�) for starters, but I do understand the issues with contract assembly. I'd be inclined to write a program to pick them from that tray and place them into a proper one.

What data are you referring to that suggests that baking at temps of 90� and above is harmful?

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#52982

Baking components at 70 degree | 19 December, 2007

gersla: You're correct that carriers of low temperature material will disfigure and become useless at 125*C bake temperatures.

The reason you can not find 70*C bake data is: J-STD033B, "4.2.2 Low Temperature Carriers. SMD packages shipped in low temperature carriers may not be baked in the carriers at any temperature higher than 40�C. If a higher bake temperature is required, SMD packages must be removed from the low temperature carriers to thermally safe carriers, baked, and returned to the low temperature carriers. Note 1. Manual handling may increase the risk of mechanical and/or ESD damage. Note 2. If SMD packages are placed in dry bags with unbaked carriers, refer to 3.3.2.2."

So, what is the origin of the 70*C number that you use?

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#52983

Baking components at 70 degree | 19 December, 2007

Nerdyboy don't write no blanking program. Get two extra carriers of the same size and configuration as the low temperature carrier that you want bake at a higher temperature. One of the these extra carriers needs to be high temperature material that you'll use last. * Place the low temperature material carrier on the table so that you can see the components. * Place one of the extra carriers with cavities down, pin one notation aligned, bla bla bla on top of the low temperature material carrier. * Holding both carriers, turn them upside down. When you take the low temperature material carrier off, the components are in a different carrier, but are bug-up. So, you need to repeat the process one more time. * Place the first extra carrier on the table so you can see the components. * Place the second extra carrier [this must be a high temperature material carrier] with cavities down, pin one notation aligned, bla bla bla on top of the first extra carrier. * Holding both carriers, turn them upside down. * Vola!! Presto chango!! The components are in a new high temperature carrier, bug-down ready to to get baked. So to speak.

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#52987

Baking components at 70 degree | 20 December, 2007

As I told you, some carriers (trays) are limited to 75 degree maximum, and from time to time employees do not pay attention to this. This is one of the reasons. The second reason is that 90 degree still be problematic in a case of rebake more then 3 times. So 70 degree can be most suitable. Can you help me with calculation? Kindly advice.

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#52994

Baking components at 70 degree | 20 December, 2007

You could have said "why don't you just flop 'em over twice into the right tray?" lol.

Yeah, that's the right way. I was kind of focused on what I had to do here to get two different parts from full trays into two cut-in-half-the-long-way trays since the Philips machine only holds two whole trays and I needed three parts on there. I couldn't figure out any other way that didn't involve spilling parts or bending leads.

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#53002

Baking components at 70 degree | 20 December, 2007

We know of no such calculation. We just follow the standard.

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#53033

Baking components at 70 degree | 27 December, 2007

Davel, I think you are right. It is better to follow J-STD. In the version B mentioned (BGA package >17 mm x 17 mm or any stacked die package). What is stacked die package? Can you send me a picture of such a component? Thank you in advance,

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#53034

Baking components at 70 degree | 27 December, 2007

gersla: For more on stacked die packaging: * Look here http://ap.pennnet.com/Articles/Article_Display.cfm?Section=Archives&Subsection=Display&ARTICLE_ID=209839

* Google => stacked die packaging

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#53037

Baking components at 70 degree | 27 December, 2007

Mr. Wizard- Bingo, you did it again - don't know why I had to wait for the 3DBB before I saw the light. I have similar sitiaction to Steve - shake and bake, baby - two turns of the rotisserie-

now ya got 2 bottles of californy spill on reserve - direct from hotel california- FOB Las Vegas- give a holler when you are coming by-

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#53038

Baking components at 70 degree | 27 December, 2007

Thank you Bubba

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#53085

Baking components at 70 degree | 6 January, 2008

My recommendation is that you send all your question to Mumtaz Y. Bora, Sr. Staff Component Engineer from Kyocera Wireless (mbora@kyocera-wireless.com). She is also a member of the committee that is writing the new specifications for Moisture Sensitive Devices. Now with the Lead-free components there are more factors to consider. If you need more specific information send me an email with the component information. For low temp carriers the time is extrapolated if lead time is not an issue.

Thanks

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#53101

Baking components at 70 degree | 7 January, 2008

> As I told you, some carriers (trays) are limited > to 75 degree maximum, and from time to time > employees do not pay attention to this. This is > one of the reasons. The second reason is that 90 > degree still be problematic in a case of rebake > more then 3 times. So 70 degree can be most > suitable. Can you help me with calculation? > Kindly advice.

> As I told you, some carriers (trays) are limited > to 75 degree maximum, and from time to time > employees do not pay attention to this. This is > one of the reasons. The second reason is that 90 > degree still be problematic in a case of rebake > more then 3 times. So 70 degree can be most > suitable. Can you help me with calculation? > Kindly advice.

I recognize that sometimes you get the packaging you get, and you may not have high temp carriers for that particular part laying around.

You could calculate ratios between 40 or 90, or use the time for the 40 to be really conservative. I do recognize that repetitive baking just eventually oxidizes the terminations and degrades solderability, but it takes a few cycles. But I'm not a fan of arbitrarilly baking things constantly.

If you want to get scientific about it, you could run a weight loss experiment. You need a very sensitive balance and for small parts you want to do a lot of them to get some resolution. Basically, you weigh the parts and keep baking them until the weight loss (the driving off of the moisture) stabilizes. When you do this, you will find that the standards are insanely conservative about the bake times.

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#55018

Baking components at 70 degree | 6 June, 2008

We have spent more than two years characterizing 70 deg C dry baking. For more information visit our website http://www.InnovativeDryingCo.com

I hope you find your answers there

Best Regards Stu Leech

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#55081

Baking components at 70 degree | 17 June, 2008

Vacuum baking oven can solve it. At 70 degree and 24 hours. And the vacuum is below than 10pa

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#55087

Baking components at 70 degree | 17 June, 2008

You are correct. For the 70 deg. C drying temperature to be effective, the relative humidity must be as near to zero as possible. A pulling a vacuum on the chamber is an inexprensive and reliable way to accomplish this. Contrary to some claims, our experiments showed that vaccuum does not accelerate the rate of moisture-removal from plastic packages.

We also found that temperatures below 70 deg. C were not effective driving-out ingested moisture.

J-Std-033B doesn't list a 70 deg C baking temperature. however under the footnote to Table 4.1, there are provisions made for alternative baking schedules that "conform" to the spec. We presented our findings to IPC/JEDEC Subcommittee JC14.1 who writes J-Std 033 last year.

We showed that if you tightly control your temperature and properly tool your oven, you can safely dry packages that are in commercial "low-temp" tube, trays or tape and reel.

You can find our "Experimental Findings" on our website at http://www.InnovativeDryingCo.com.

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#55089

Baking components at 70 degree | 17 June, 2008

But don't you need to control the rate of the drop in pressure? I'd think if you pull down quickly it just results in the same popcorning you'd see in a reflow oven.

I just know it's not hard to boil water in a vacuum chamber. For that matter, it's not hard to freeze it, and it's even more fun to have all three phases at the same time. :)

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#55090

Baking components at 70 degree | 17 June, 2008

And we have evaluated this process before 2001. And it is widely used in our company world wide. And we don't control the rate of the drop in pressure, because it is same as 125 degree at normal pressure condition.

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#55092

Baking components at 70 degree | 18 June, 2008

Innovative Drying Co., considered this possibility early in our experiments. The rate of chamber pump-down is not a consideration. However, the selection of the vacuum pump is critical. Avoid oil-sealed pumps at all costs. A poorly maintained oil-trap will result in oil back-creeping (against the direction of the gas-flow). The smallest amount of vaporized oil in the chamber will rack havoc with the solderability of the packages.

If you have attempted to clean an oil-conatiminated vacuum system, you know what hell feels like

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#55096

Baking components at 70 degree | 18 June, 2008

Hi Stu

Some seem to believe that vacuum baking will suck moisture from components and boards. Actually, the case is just the opposite. * Without proper definition and control of process parameters, vacuum baking retards the removal of moisture * Even with proper definition and control of process parameters, at best, vacuum baking is a minor improvement over traditional baking methods

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#55105

Baking components at 70 degree | 18 June, 2008

Dave, can I assume that in the case(s) you're referring to, there was no gas introduced into the evacuation chamber to push any expelled moisture out of the system?

In the industry I was involved with (implantable medical devices), we used nitrogen to backflush the system. You do have to allow something in at these vacuum levels or nothing can leave.

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#55106

Baking components at 70 degree | 18 June, 2008

"And we have evaluated this process before 2001."

How did you quantify the level of moisture left in the components after the bake?

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#55111

Baking components at 70 degree | 18 June, 2008

Dave:

You are spot-on right! The major hurdle is that 70 degrees C is below the boiling temperature of water. Only a near zero relative hudity chamber will cause the ingested moisture to migrate from a package.

There is one facet of the 70 degree process that has not been mentioned on this thread. A 24-hour baking cycle DOES NOT reset the "floor-life" of a "wet" packge. It does however recover 50% or more of the J-Std-033B specified "floor-life."

The baking schedules listed in J-Std-033B are intended to completely return the packages to their dry-state, which assures semiconductor manufacturers that there is little chance for moisture-ingested package delamination.

The spec overlooks the fact that the majority of moisture is removed in the first 24-hours of baking. The remainder of the baking schedule is used to remove a very small amount of moisture from the package.

Our goal was only to recover 50% of the package's "floor-life," giving you ample time to place the component and reflow the board.

There is a narrated PowerPoint presentation available on our website http://www.InnovativeDryingCo.com. View "The Glass Half-Full" on our Presentation/Media page.

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#55125

Baking components at 70 degree | 19 June, 2008

And that's the key thing for an assembler. Who cares if the part is bone dry? Assemblers want to get the part dry enough so that soldering process does not destroy the part, so that he /she can move on to the next issue.

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#55203

Baking components at 70 degree | 24 June, 2008

Qulification the baking process of 70 degree and 24 hours below 10Pa. We have the experiment data which shows the weight of baked water from package with this condition is more than 125 degree at normal condition.

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#55207

Baking components at 70 degree | 25 June, 2008

Questions are: * What does "weight of baked water from package with this condition [70 degree and 24 hours below 10Pa] is more than 125 degree at normal condition" mean? * What is "normal condition"?

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#55212

Baking components at 70 degree | 25 June, 2008

I would love to see the documentation of the experiment that indicated that a 24-hour/70 degree C bakeiing cycle at 10Pa is more effetive than a 24-hour 125 deg C baking cycle at normal atmosphere. We have looked at the old Levey-Perlmann paper and found a couple of significant errors in their methodology.

We have posted our DoE and findings on our website http://www.InnovativeDryingCo.com.

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#55221

Baking components at 70 degree | 25 June, 2008

Sorry! I can't insert the document. So give me email if you want to receive this evaluation report.

fowlerchang@rayval.com

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#55278

Baking components at 70 degree | 28 June, 2008

Fowler:

Thank you for your documentation. Your finding roughly coincide with our own. We also found that 70 degree baking removes 50%/60% of the ingested moisture from moisture conditioned MSD packages

We ran an additional experiment that compared 125 degree atmospheric pressure and 125 degree with vacuum (100 Torr). No improvement was seen from the use of vacuum.

We see evidence that use of vacuum in a 70 degree baking schedule assures that the relative humidity in the chamber is reduced to near-zero.

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