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Popcorn @ reflow

Omat Marasigan

#11412

Popcorn @ reflow | 19 May, 1999

hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is...

your help is greatly appreciated...thanks

omat marasigan

reply »

Earl Moon

#11413

Re: Popcorn @ reflow | 20 May, 1999

| hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | your help is greatly appreciated...thanks | | omat marasigan | | Omat baby,

Moisture sensitivity is becoming a popcorning issue with more of us. It is so much so with us now, we may prematurely release a process without our usual exhaustive evaluation and qualification.

Mostly, this phenomonon involves moisture sensitive parts. These parts encompass many varieties and styles, though mostly BGA types. Most all popular BGA's, and many other leaded/plastic parts (in particular) are moisture sensitive requiring special attention before soldering operations.

Included in popcorning prevention is a specified process involving buying parts presealed and certified safe from various suppliers. Inside moisture sensitive/ESD protective bags are certs, dessicants, and moisture sensitive labels. Assurance must be provided, first, from the supplier their moisture sensitive parts are moisture protected.

Next, upon opening your prize parts, you must continue moisture sensitive assurances. This is done using IPC/supplier specifications concerning how long parts may be left exposed to the environment, under what conditions, before they must be rebaked/resealed and reused.

IPC has pretty good guidelines supporting most supplier moisture sensitive requirements. They range from 1 through 6 classes of sensitivity. This means some parts are less/more sensitive than others and require more/less attention to use/time factors.

Anyway, if your parts are moisture sensitive and you do not pay attention to moisture sensitive requirements, and you solder them in reflow or over the wave, you will blow the little bastards apart. Any more questions?

I wish you the best while hoping you don't end up eating some of the results,

Earl Moon

reply »

JohnW

#11414

Re: Popcorn @ reflow | 20 May, 1999

Earl,

your colourful impressive descrptions are a joy to read..well lighten's up my day but maybe it's just me...ummmm..?

anyhoo, Omat, as Earl has said ..this is a moisture sensative problem basically the reason you blow the shit out of the components is that the moisture level in the component reaches a given level..varies by type size yada yada yada... As it moves thro the reflow ..getting hotter (well hopefully) the moisture changes state to a gas and expand's inside the space causing the component to swell..eventually the material let's go and the small explosion earl describ'es happens..simple really but great fun to watch!!! If it's a problem the IPC guidelines are great cant remember if they give backing times for components but your manufacturer will. A tip if your not already doing it is to get labels for the part's identifying the level of moisture sensitivity and a grid where you can write on the time it was opened / reseald adn the time remaining..e.g. you got a 12hr part..it's opened at 3pm and you only use say a tray..and reseal it at 9pm. So 6hr's have passed..your got 6hrs before you have to bake the components.

JohnW

| hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | | | your help is greatly appreciated...thanks | | | | omat marasigan | | | | | Omat baby, | | Moisture sensitivity is becoming a popcorning issue with more of us. It is so much so with us now, we may prematurely release a process without our usual exhaustive evaluation and qualification. | | Mostly, this phenomonon involves moisture sensitive parts. These parts encompass many varieties and styles, though mostly BGA types. Most all popular BGA's, and many other leaded/plastic parts (in particular) are moisture sensitive requiring special attention before soldering operations. | | Included in popcorning prevention is a specified process involving buying parts presealed and certified safe from various suppliers. Inside moisture sensitive/ESD protective bags are certs, dessicants, and moisture sensitive labels. Assurance must be provided, first, from the supplier their moisture sensitive parts are moisture protected. | | Next, upon opening your prize parts, you must continue moisture sensitive assurances. This is done using IPC/supplier specifications concerning how long parts may be left exposed to the environment, under what conditions, before they must be rebaked/resealed and reused. | | IPC has pretty good guidelines supporting most supplier moisture sensitive requirements. They range from 1 through 6 classes of sensitivity. This means some parts are less/more sensitive than others and require more/less attention to use/time factors. | | Anyway, if your parts are moisture sensitive and you do not pay attention to moisture sensitive requirements, and you solder them in reflow or over the wave, you will blow the little bastards apart. Any more questions? | | I wish you the best while hoping you don't end up eating some of the results, | | Earl Moon |

reply »

DEON NUNGARAY

#11415

Re: Popcorn @ reflow | 20 May, 1999

| hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | your help is greatly appreciated...thanks | | omat marasigan | Deon Response:|

Hello Omat, Both gentlemen Earl and John are correct about popcorning. What does popcorning actually look like? Well this depends on how much moisture is in your component to begin with. From my experience the more common effect of popcorning encoutered is post reflow component cooplanarity problems. For example on a fine pitch device three sides of the component are soldered flat on the PCB while one side is actualy lifted not sitting flat on the board surface. It almost looks like the leads on the component are bent up. Not so, what has happened is that the actual ceramic body of the part has warped while releasing moisture in the reflow process at an accelerated rate.POP!!!

How to fix?

Bake your moisture sensitive components before using them if the original packaging looks like it has been tampered with. Do not assume that they are probably okay to use. This can be a very costly assumption. Touch up, rework, scrap etc... You can look up baking specs. on the IPC or Motorola publications as mentioned. I typically bake my componenets @110 C for 24 hours prior to use. Hope this answers you questions.

Deon Nungaray SMT Mfg. Process Engineer General Monitors USA CA

reply »

Earl Moon

#11416

Re: Popcorn @ reflow | 20 May, 1999

| | hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | | | your help is greatly appreciated...thanks | | | | omat marasigan | | | Deon Response:| | | Hello Omat, | | Both gentlemen Earl and John are correct about popcorning. What does popcorning actually look like? Well this depends on how much moisture is in your component to begin with. From my experience the more common effect of popcorning encoutered is post reflow component cooplanarity problems. For example on a fine pitch device three sides of the component are soldered flat on the PCB while one side is actualy lifted not sitting flat on the board surface. It almost looks like the leads on the component are bent up. Not so, what has happened is that the actual ceramic body of the part has warped while releasing moisture in the reflow process at an accelerated rate.POP!!! | | How to fix? | | Bake your moisture sensitive components before using them if the original packaging looks like it has been tampered with. Do not assume that they are probably okay to use. This can be a very costly assumption. Touch up, rework, scrap etc... You can look up baking specs. on the IPC or Motorola publications as mentioned. I typically bake my componenets @110 C for 24 hours prior to use. Hope this answers you questions. | | Deon Nungaray | SMT Mfg. Process Engineer | General Monitors USA CA |

This is great,

We've covered most of the bases. Another way to determine popcornininining effects is to perform x-ray analysis. Of course, this too late but it provides possible evidence the occurrence took place. Often this is manifested as wire bonded leads "blown" away.

I had no idea there were so many intersted and knowledgeable parties. I should have known better, but I've made assumptions before promising never to assume anything agin.

You folks really nailed this one, with some more stuff to go. One is creating a realistic data base to distinguish those parts moisture sensitive. How many can there be, and who is responsible for monitoring the system, baking the parts (one of our material people said there was no way she was going to cook here and for the old fart at home), re-sealing them, finding the best vacuum sealing sytstem in the first place to go along with which ovens and who will do what, where, when, why, and how. It gets more interesting all the time especially when people constantly resist change in an increasingly (exponential) changing world.

And on it goes,

Earl Moon

reply »

KA Stillings

#11417

Re: Popcorn @ reflow | 21 May, 1999

| | hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | | | your help is greatly appreciated...thanks | | | | omat marasigan | | | | | Omat baby, | | Moisture sensitivity is becoming a popcorning issue with more of us. It is so much so with us now, we may prematurely release a process without our usual exhaustive evaluation and qualification. | | Mostly, this phenomonon involves moisture sensitive parts. These parts encompass many varieties and styles, though mostly BGA types. Most all popular BGA's, and many other leaded/plastic parts (in particular) are moisture sensitive requiring special attention before soldering operations. | | Included in popcorning prevention is a specified process involving buying parts presealed and certified safe from various suppliers. Inside moisture sensitive/ESD protective bags are certs, dessicants, and moisture sensitive labels. Assurance must be provided, first, from the supplier their moisture sensitive parts are moisture protected. | | Next, upon opening your prize parts, you must continue moisture sensitive assurances. This is done using IPC/supplier specifications concerning how long parts may be left exposed to the environment, under what conditions, before they must be rebaked/resealed and reused. | | IPC has pretty good guidelines supporting most supplier moisture sensitive requirements. They range from 1 through 6 classes of sensitivity. This means some parts are less/more sensitive than others and require more/less attention to use/time factors. | | Anyway, if your parts are moisture sensitive and you do not pay attention to moisture sensitive requirements, and you solder them in reflow or over the wave, you will blow the little bastards apart. Any more questions? | | I wish you the best while hoping you don't end up eating some of the results, | | Earl Moon | Everything I've read on this issue is exactly what we had to do with our components. We placed moisture labels and baked and tracked parts, etc... finally found out the problem was coming from the distributors location - they left the cartons or reels, or tubes on the dock in the rain to wait for shipping... need I say more. Popcorning is a very cool process to see even if it does cause real big headaches. Antoher after-the-fact way of verifying the problme is using pcb cross-sectioning equiment to cut the part open and then you can see a side view of the "bubble".

reply »

JohnW

#11418

Re: Popcorn @ reflow | 21 May, 1999

| | | hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | | | | | your help is greatly appreciated...thanks | | | | | | omat marasigan | | | | | Deon Response:| | | | | Hello Omat, | | | | Both gentlemen Earl and John are correct about popcorning. What does popcorning actually look like? Well this depends on how much moisture is in your component to begin with. From my experience the more common effect of popcorning encoutered is post reflow component cooplanarity problems. For example on a fine pitch device three sides of the component are soldered flat on the PCB while one side is actualy lifted not sitting flat on the board surface. It almost looks like the leads on the component are bent up. Not so, what has happened is that the actual ceramic body of the part has warped while releasing moisture in the reflow process at an accelerated rate.POP!!! | | | | How to fix? | | | | Bake your moisture sensitive components before using them if the original packaging looks like it has been tampered with. Do not assume that they are probably okay to use. This can be a very costly assumption. Touch up, rework, scrap etc... You can look up baking specs. on the IPC or Motorola publications as mentioned. I typically bake my componenets @110 C for 24 hours prior to use. Hope this answers you questions. | | | | Deon Nungaray | | SMT Mfg. Process Engineer | | General Monitors USA CA | | | | | This is great, | | We've covered most of the bases. Another way to determine popcornininining effects is to perform x-ray analysis. Of course, this too late but it provides possible evidence the occurrence took place. Often this is manifested as wire bonded leads "blown" away. | | I had no idea there were so many intersted and knowledgeable parties. I should have known better, but I've made assumptions before promising never to assume anything agin. | | You folks really nailed this one, with some more stuff to go. One is creating a realistic data base to distinguish those parts moisture sensitive. How many can there be, and who is responsible for monitoring the system, baking the parts (one of our material people said there was no way she was going to cook here and for the old fart at home), re-sealing them, finding the best vacuum sealing sytstem in the first place to go along with which ovens and who will do what, where, when, why, and how. It gets more interesting all the time especially when people constantly resist change in an increasingly (exponential) changing world. | | And on it goes, | | Earl Moon | Earl..we used the IPC recomended classes and get Stores to apply the lables @ good's in / locating the parts. They also bake eem as soon as they are returned from the floor and attach a 2nd albel after plus a small label saying that it was baked..cos let's face it you dont wanna be doing that too many times..and as much as I hate to admit it they do not a bad job of it.

On thought that i did have..was that if there is a big problem with the moisture sensitive part's it usually because u aint used them quick enough after opening the packs. We had this problem on 1 customer that we built real lo volumes for..so we nagged the hell out the buyers till they bought in lower packed qty's - same overall qty but only 1 or 2 tray's to a pack..it helped a lot..

JohnW

reply »

Omat Marasigan

#11419

Re: Popcorn @ reflow | 22 May, 1999

| Earl, | | your colourful impressive descrptions are a joy to read..well lighten's up my day but maybe it's just me...ummmm..? | | anyhoo, Omat, as Earl has said ..this is a moisture sensative problem basically the reason you blow the shit out of the components is that the moisture level in the component reaches a given level..varies by type size yada yada yada... | As it moves thro the reflow ..getting hotter (well hopefully) the moisture changes state to a gas and expand's inside the space causing the component to swell..eventually the material let's go and the small explosion earl describ'es happens..simple really but great fun to watch!!! | If it's a problem the IPC guidelines are great cant remember if they give backing times for components but your manufacturer will. | A tip if your not already doing it is to get labels for the part's identifying the level of moisture sensitivity and a grid where you can write on the time it was opened / reseald adn the time remaining..e.g. you got a 12hr part..it's opened at 3pm and you only use say a tray..and reseal it at 9pm. So 6hr's have passed..your got 6hrs before you have to bake the components. | | JohnW | | | | hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | | | | | your help is greatly appreciated...thanks | | | | | | omat marasigan | | | | | | | | Omat baby, | | | | Moisture sensitivity is becoming a popcorning issue with more of us. It is so much so with us now, we may prematurely release a process without our usual exhaustive evaluation and qualification. | | | | Mostly, this phenomonon involves moisture sensitive parts. These parts encompass many varieties and styles, though mostly BGA types. Most all popular BGA's, and many other leaded/plastic parts (in particular) are moisture sensitive requiring special attention before soldering operations. | | | | Included in popcorning prevention is a specified process involving buying parts presealed and certified safe from various suppliers. Inside moisture sensitive/ESD protective bags are certs, dessicants, and moisture sensitive labels. Assurance must be provided, first, from the supplier their moisture sensitive parts are moisture protected. | | | | Next, upon opening your prize parts, you must continue moisture sensitive assurances. This is done using IPC/supplier specifications concerning how long parts may be left exposed to the environment, under what conditions, before they must be rebaked/resealed and reused. | | | | IPC has pretty good guidelines supporting most supplier moisture sensitive requirements. They range from 1 through 6 classes of sensitivity. This means some parts are less/more sensitive than others and require more/less attention to use/time factors. | | | | Anyway, if your parts are moisture sensitive and you do not pay attention to moisture sensitive requirements, and you solder them in reflow or over the wave, you will blow the little bastards apart. Any more questions? | | | | I wish you the best while hoping you don't end up eating some of the results, | | | | Earl Moon | | | | DEON, EARL, JOHN & KA Stillings,

THANKS A LOT FOR THE INFO!!!

...Omat marasigan

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