Which is best for reballing 138° or 183° solder paste ?

[G33RT]

Can someone tell me what solder paste is best for reballing pmic and wifi chip.

138° or 183° solder paste ?

[R7027]

Doesn't that depend on the temperature you can heat it at? If you use 183 degrees solder paste, you would need to heat it at 183 degrees. I think. I'm no expert. Maybe I don't understand the problem. But what unit is this in? Fahrenheit?

[G33RT]

Originally Posted by R7027

Doesn't that depend on the temperature you can heat it at? If you use 183 degrees solder paste, you would need to heat it at 183 degrees. I think. I'm no expert. Maybe I don't understand the problem. But what unit is this in? Fahrenheit?

The unit of heat is expressed here in Celsius.
There is no problem, I just like to know others opinion on this and mabe there are some experts around on this forum.
If I use the standard 217°C solder paste the components around the IC that I want to re-ball would heat-up to much, that's why we use a lower melting point solder to avoid damaged on other components.

[R7027]

Now I understand the problem. Hm... in that case, I think I would select the lower melting point, the 138 C solder paste.


The lower the better, I think. Not only to avoid melting the solder joints on the other components, but also to protect the other components from overheating and heat damage.


For example, if the healthy components are soldered with a 150 C solder from factory, then I would not use the 183 C solder paste for reballing my component. I would use 138 C solder paste instead, just to stay below 150 C. This protects the other components better from overheating, and it avoids melting and resetting their solder joints, as I solder in or heat solder the new component in.


As a non-expert, I would imagine that frequent heating (melting) and cooling (solidifying) of solder joints could lead to cracked solder points, and a faulty component or device as a result. Actually this might be the way that some devices get a short, they keep being heated up and cooled down. But I have never in my life reballed a BGA chip. So take what I say with a pinch of salt. I don't have the skill or experience, but I know how it's done, I have seen it done many times. Like I said, I am no expert, but I understand the problem now, and if I was doing that myself, I would try to stay away from that critical melting point for the components that are already on the board.


But what is that critical melting point anyway? Does anyone here know for a fact what solder is used on a modern Samsung smartphone for example? I suspect no one knows this, and if you don't know, then you're guessing. But in any case, I think it's safer to stay on the low side, so I would go for 138 C solder paste.



You probably don't want to use a solder paste with a very low melting point, like, I don't know... maybe 115 C, if it exists. The lower it gets, the easier it is to melt it. You don't want it to melt on its own. For example, if solder paste with melting point of 95 C existed (presumably it does not), I would imagine that the component you solder in now, would desolder on its own on a hot summer day with ambient temperature of 35 C. It could get as hot as 70 C or more inside the phone, if left out in the sun. Or if you use 150 C or more on a hot air station to heat the phone up so you can open it up. That would also cause your component to desolder and start to travel on the board.


So the question becomes, how hot is your environment where you will be using the device? What operating temperature? It's undoubtedly going to be different in northern hemisphere than in southern hemisphere.


Other things that might influence the decision between 138 C and 183 C might be where your component is located on the board. Is it near the CPU or other heat source? Are there heat sensitive or heat tolerant components around it? Also, what kind of component is it, in itself? Is it sensitive for heat? These are all things to consider.



Hopefully there are experts around here who have done a few dozens of reballing and rework jobs, and they can give their verdict. But for what it's worth, as a noob myself, I would cast my vote on 138 C solder paste.

[Xavier 03]

Tiene metodo kglocked para a 22 5g

[G33RT]

Originally Posted by R7027

Now I understand the problem. Hm... in that case, I think I would select the lower melting point, the 138 C solder paste.


The lower the better, I think. Not only to avoid melting the solder joints on the other components, but also to protect the other components from overheating and heat damage.


For example, if the healthy components are soldered with a 150 C solder from factory, then I would not use the 183 C solder paste for reballing my component. I would use 138 C solder paste instead, just to stay below 150 C. This protects the other components better from overheating, and it avoids melting and resetting their solder joints, as I solder in or heat solder the new component in.


As a non-expert, I would imagine that frequent heating (melting) and cooling (solidifying) of solder joints could lead to cracked solder points, and a faulty component or device as a result. Actually this might be the way that some devices get a short, they keep being heated up and cooled down. But I have never in my life reballed a BGA chip. So take what I say with a pinch of salt. I don't have the skill or experience, but I know how it's done, I have seen it done many times. Like I said, I am no expert, but I understand the problem now, and if I was doing that myself, I would try to stay away from that critical melting point for the components that are already on the board.


But what is that critical melting point anyway? Does anyone here know for a fact what solder is used on a modern Samsung smartphone for example? I suspect no one knows this, and if you don't know, then you're guessing. But in any case, I think it's safer to stay on the low side, so I would go for 138 C solder paste.



You probably don't want to use a solder paste with a very low melting point, like, I don't know... maybe 115 C, if it exists. The lower it gets, the easier it is to melt it. You don't want it to melt on its own. For example, if solder paste with melting point of 95 C existed (presumably it does not), I would imagine that the component you solder in now, would desolder on its own on a hot summer day with ambient temperature of 35 C. It could get as hot as 70 C or more inside the phone, if left out in the sun. Or if you use 150 C or more on a hot air station to heat the phone up so you can open it up. That would also cause your component to desolder and start to travel on the board.


So the question becomes, how hot is your environment where you will be using the device? What operating temperature? It's undoubtedly going to be different in northern hemisphere than in southern hemisphere.


Other things that might influence the decision between 138 C and 183 C might be where your component is located on the board. Is it near the CPU or other heat source? Are there heat sensitive or heat tolerant components around it? Also, what kind of component is it, in itself? Is it sensitive for heat? These are all things to consider.



Hopefully there are experts around here who have done a few dozens of reballing and rework jobs, and they can give their verdict. But for what it's worth, as a noob myself, I would cast my vote on 138 C solder paste.

At the factor they use unleaded solder and it's melting point is 217°C
The good stuff (leaded solder paste) 183° is used in medical devices, aviation and space equipment.

So I think I can't do anything wrong by using 183°C solder paste

[R7027]

There you go! See? I told you! I told you to get the 183 C stuff.


FWIW, 183 C is 34 C below 217 C. So it's safe from melting other components. Well, as long as it's not medical or aviation equipment.


What phone is this? Some Samsung Galaxy? I have a Galaxy S7 with bad PMIC (I think). I ordered a few new PMIC chips, and they came with their balls showing.



So I won't have to buy stencil and soldering paste. But watching others do this type of job, I can tell it's a messy job, and how well you can do it all depends on your experience and skill, and of course access to tools and the right soldering paste. Seeing these new chips with bare eyes, I have great respect for how tiny and fragile these things are. I have steady hands and slim fingers, but I'm not so sure I would be able to make the balls so perfectly round even with the right tools. They are very tiny and I don't have a microscope yet.


So I will wait till I have some kind of microscope before I even attempt to do this type of job. I do have about four Galaxy S7 phones to practice on, two of which are in the mail and on their way to me. I already broke one of them, thanks to ESD I think. I purchased a few perfectly fine and working Galaxy S7 just for testing, practice, and for donating spare parts, before I attempt to do any operation on the main patient. This is quickly turning into a costly experiment and hobby for me. I have never done anything like this before, but I have learned a lot in the process. It's priceless when you can fix something by yourself. I'm a fixer and I love solving problems.


I ordered the very special "boot" DC power cable from China today via Ebay, along with a new set of test leads with precision test tips. I hope these new test leads are better than the ones I got in a test lead kit I ordered from Amazon that are too soft and bend when you press the handles. I also ordered a thermal camera from China last week, the very best one from Infiray. I hope to get it in mid January.

[R7027]

I just got news that my thermal camera is on its way. Now I only need to get a microscope and I have no idea what to buy. I have to do some research on this.

After some practice and some failures, I could probably start a company and open for business. Competition is practically zero in this field where I live, no one does component level repairs in the whole country, not even Samsung service centers. Especially not them, they only showcase latest models when you visit their service center. That's how you know you're in the wrong place. But I'm not sure I will go in that direction. This is mostly a one time thing for me. I'm doing this because a professional repair shop that does level 3 repairs has failed to repair my phone. But I don't believe it's because they could not do it, it's because they didn't even try. I lost all trust and confidence in them when they sent me back my phone without the internal 12 screws (I counted them) that I so carefully had put in a small zip bag and sent to them along with the phone. I took photos of everything before I sent it, as if I anticipated something could go wrong. Now I can do before and after comparison, and prove that screws are missing.

When they told me they could not repair it, I asked that they return my phone to me. They asked how I wanted it, assembled or disassembled, and they said they would charge me for assembly whereas sending it disassembled was free of charge and I only needed to pay for return shipping. They ask every customer the same question, this is normal procedure at this company. I told them to send it disassembled, and they sent the phone and all the parts back to me, but the screws were missing. Just because they didn't do the assembly! Some professionals! More like professional crooks. Professionals don't steal screws from its customers! So low! I would not have believed something like this existed if someone had told me.

You know, I was the one who took my own phone apart in the first place (to see if it had a bad battery), before sending it to them. I know how to put it back together (I just needed to buy the right glue). Why would I pay them to do what I myself am competent enough and willing to do at home? I'm not an idiot. They asked and I accepted the terms for the return, they just didn't tell me they would take my screws away if I selected to receive it disassembled. How can I know if they don't tell me? Thankfully, they sent me my phone back, even if the screws were missing.

It was a mail-in order to a company in Germany. I asked them about this later. They explicitly told me it's because I selected to receive it disassembled! I have everything on record, in written form. But nowhere did they say they would omit the screws because of this. I kindly asked them to send the screws by regular mail letter via Deutsche Post (the weight is as low as a single A4 sheet of paper), and I would pay them full amount for return shipping by UPS Express parcel, i.e. I offered to overpay them just to see them send my screws back to me. They went into radio silence after that and I haven't heard from them since, it's been over a month now.

I have more than one good reason to mistrust the "professionals". My brother's phone of the same model and with the same symptoms was sent in to another repair shop, to another country in Europe, and it too was considered "dead", and it was "repaired" by replacing the motherboard, something I could have done myself (apart from diagnostics).

You know... I often say that if you want something to be done right, you better do it yourself. I have never been as right about that as I am now. The older I get, the more often I'm reminded of this simple cliché. I think it's a reflection of the time we live in. Hardly anyone wants to do repair of anything, and even less people know how to do it, and even less are the people who both want to, know how to, and are willing to do a good job. There are so many bad actors pretending to be a professional and do a good job. This is true for phones, cars, and house services. I have met too many clowns in my life, and only a few really good professionals that I can vouch for. Most often, the best they can offer is a mediocre job I would not take pride in if I was in their clothes, and they only offer "around the corner" warranty on their jobs (that means plumbing is water tight until the repairman is gone). That's another thing: no one wants to take responsibility, for anything. It's a sad time for humanity I think, where everything is about money and making quick profit than being a good human and standing up for true values. Repairing things in itself is a noble thing, and it's not only a sustainable thing to do, it also teaches values and manners.

[SAEIDSANGAN]

for what ?
ic and cpu 183
dram and ufs emmc 138