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Forum Index : Microcontroller and PC projects : Cooking chips....
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vasi Guru  Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
The Bake levels. MSL levels JEDEC indicators for Microchip microcontrollers. You just need a good owen, with constant, controlled temperature. We had an electric one in our laboratory (in petroleum area of activity) where we prepared our probes, but also warming our food  . It had a thermostat with mercury. Very old. An old colleague used it to bake some electronic components for a better stability.
A colleague forgot the food inside the owen and the entire building was filled with a delicious smell of Chicken steak fries and everyone got hungry instantly - half the day was ruined. Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2927 |
Thanks vasi for the links - an interesting read & very useful information. I have certainly learnt something new today. However, after all that I have decided to continue using FTDIs for now until I experience the so called 'Popcorn Cracking' Thanks all for your responses 
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9491 |
Very interesting thread for me too. 
Yes, that is my understanding. The theory(as I see it), is that reflow oven soldering can vaporise the water particles in the plastic because of the sudden heat, which then pressurize the IC package internally, and crack it. I am pretty sure that another member here wrote essentially that - would need to look back on the posts. Smoke makes things work. When the smoke gets out, it stops! |
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| vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
BTW, just saw that PIC18F14K50 which is MCP2200, is marked JEDEC e3 which is the same as MSL 3. Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2927 |
TZAdvantage better get baking his MCP2200's then 
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| vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
If baking is required, then the product become expensive because of the electric bill. Hobbyists are using sockets for dip packages and I guess this minimise the accidents at minimum in areas with high humidity. But I guess the accidents are extremely rare even for TQFP packages. Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
Wow, those soak times are pretty long Vasi. The other approach that people could use is to put the components into a standard lab/hospital dessicator bowl as soon as a sealed package is opened. If they've already been exposed (and they're the sensitive type  ) they'll probably need the 'oven soak'. Buy a kilo or so of indicating silica-gel (dead cheap - dry when blue, starts to go pink when it needs re-charging). Put 500g or so of it in a glass or metal tray in the bottom of the dessicator - it comes in granules about 4-5mm size. You're good then for at least a month if the lid's not left off for hours. Opening it up, even several times a day wouldn't make a lot of difference as long as the lid is put straight back on - otherwise you're trying to dry the whole room!
For those who haven't seen them, desiccators are heavy round glass bowls with a wide ground-glass seal between the lid and body - it's all glass. They're typically about 300mm dia. x 350mm high, but come in all sizes. The seal is made with a smear of silicone grease on the ground part and the seal is so good that the lid needs some force to be slid off. You can stack trays inside it. I haven't bought them for a long time but they're pretty cheap. The silica gel needs re-charging before using it in the desiccator and that's done by heating it a bit above 100oC overnight in an oven - labs have their ovens set at 105oC but as long as it's over 100oC it's not critical. The idea is to keep the silica-gel you're not using in an air-tight container, then put it into the oven overnight before you change the charge in your desiccator once a month or so. The used stuff should also be dried after taking it out before re-bottling it because if you don't, it severely cuts back the number of re-charges it'll take. Typically silica-gel should last a couple of years. You'll know when it's no longer any good because it'll start to go yellow/clear-ish and not return to blue. Greg |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
This is incorrect. The e3 indicator is used to indicated which materials are used. It is a "Lead free" indicator not a Moisture Sensitivity Level. e1 - SnAgCu e2 - Other Sn alloyes - no Bi or Zn e3 - Sn e4 - Pre-plated (i.e. Ag, Au, NiPd, NiPdAu) e5 - SnZn, SnZnX (no Bi) e6 - Contains Bi e0,e7,e8,e9 are still unassigned These are the Moisture Sensitivity Levels (MSL). Microchip does not have a 'list' as far as i know. [code] 1 Unlimited ≤30°C/85%RH 2a 4 weeks ≤30°C/60%RH 3 168 hours ≤30°C/60%RH 4 72 hours ≤30°C/60%RH 5 48 hours ≤30°C/60%RH 5a 24 hours ≤30°C/60%RH 6 Time on Label (TOL) ≤30°C/60%RH [/code] As you can see when having stock you need to go through great lengths especially in Thailand where temperatures are often above 30 and humidity above 85% (about 1-2 months per year Thailand is below those figures). Even the MSL 1's can be susceptible to it. Storing components is a challenge. Moisture removal, temperature etc. Sensitive components go into a "fridge" and stay in the manufacturers packaging as long as possible also the solder paste which does not like warmth and moisture either. Baking is not too difficult when you have a reasonable temperature control. I have talked to Microchip directly about these levels for specific chips and they insured me that the chips with MSL-1 do not have to be baked (Thailand conditions). Even after a few years. If that is true or not that is hard to make sure. Experience tells me it is true. Microblocks. Build with logic. |
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| vasi Guru Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
Yes, my bad, that was incorrect. Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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