What kind of acid is in acid-free solder paste?

吾妻思萌

What kind of acid is in acid-free solder paste? [Copy link]

 

rt, teachers, what is the acid in acid-free solder paste? Someone asked me and I was confused.

maychang

“Acid-free” means “no acid”, no acid at all. What kind of acid do you say it is?

lugl4313820

I also want to know what kind of acid it is. It can't be liquid acid, nitric acid or something like that.

ufoer11

It seems that the acid solder paste in the past contained hydrochloric acid, which was effective, but did not clean thoroughly, became corrosive over time, and was prone to poor contact.

led2015

Solder paste usually contains colloid, activator and flux. "Acid-free" means no chloride acid

Jacktang

Potassium chlorate is toxic.

What the hell is chloride-free acid, non-toxic?

吾妻思萌

"Acid-free" means "no acid", no acid at all. What kind of acid is that?

Oh, the teacher's answer is correct. I want to ask what kind of acid is in the "acid-containing" solder paste.

吾妻思萌

It seems that the acid solder paste in the past contained hydrochloric acid, which was effective, but it was not cleaned thoroughly, and it became corrosive over time, which made it easy to have poor contact.

The flux cl root was corrosive, but the current one is not corrosive. I understand ~ it is not a specific acid.

maychang

Azuma Simeng posted on 2023-5-3 16:15 Oh, oh, there is nothing wrong with the teacher's answer. I want to ask what kind of acid is in the "acidic" solder paste~

"Acidic" solder paste usually contains some weak organic acids, such as salicylic acid, tartaric acid, citric acid...

吾妻思萌

I also want to know what kind of acid it is. It can't be liquid acid or nitric acid.

No, no, it will evaporate when heated. The engineer must be poisoned.

吾妻思萌

Solder paste usually contains colloid, activator and flux. "Acid-free" means no chloride acid

It's not quite the same as what the teacher said ~ I seem to have heard the old master say that chlorine increases welding and lead reduces the melting point.

吾妻思萌

Azuma Simeng posted on 2023-5-3 16:15 Oh, there is nothing wrong with the teacher's answer. I want to ask what kind of acid is in the "acidic" solder paste~

The "acidic" solder paste usually contains some weak organic acids, such as salicylic acid, tartaric acid, citric acid…

Then teacher, there was a post before saying that the PCB board was whitish. Could it be that he used the acidic flux and didn't clean it thoroughly?

maychang

Azuma Simeng posted on 2023-5-4 07:25 Solder paste with "acid" usually contains some weak organic acids, such as salicylic acid, tartaric acid, citric acid...

[There was a post before saying that the PCB board was white. Could it be that he used acidic flux and didn't clean it thoroughly? ]

It's possible. I don't know the details.

chunyang

Please note that solder paste and flux paste are two different things. The manufacturer of the picture in the original post is making a fuss and mislabeled it. Judging from the main ingredient rosin, it is obviously flux paste. Solder paste is also called tin paste, and its main ingredient is metal tin.

Acid-free flux paste certainly does not contain acid, while the acidic composition of acid flux paste is very complex. The acids used in acid flux pastes for different purposes can be said to be varied, which can be roughly divided into two categories: inorganic acids and organic acids. In addition, there are also acid flux pastes that use salts.

Among them, the most common inorganic acid is hydrochloric acid, and there are more organic acids, including citric acid, salicylic acid, etc.

秦天qintian0303

Does acid-free mean no acid at all or does it mean the content is less than a certain amount?

chunyang

Qintianqintian0303 posted on 2023-5-4 15:21 Acid-free means no acid at all or the content is less than a certain amount?

Acid-free means acid-free, literally.

吾妻思萌

Qintianqintian0303 posted on 2023-5-4 15:21 Does acid-free mean no acid at all or less than a certain amount?  

Acid-free means acid-free, literally.

Teacher, I'm going off topic~ Acid-free should mean no acid added, but you really need to check it out. But I've suffered from the lead-free solder paste that was advertised (four chocolates). My former colleague and I bet that lead-free means no lead. He showed me the manual of the Japanese solder paste and found that the lead content was less than a specified value, and it was defined as "lead-free" by the association.

chunyang

Azuma Simeng posted on 2023-5-4 17:55 Acid-free means acid-free, literally. [/quote] Teacher, I'm going off topic~ Acid-free should mean no acid added, but I really need to check it out...

Strictly speaking, it also includes "salt", strong acid and weak base salt. As for "lead-free", it is impossible to be absolutely lead-free, because tin ore itself contains a certain amount of lead and other metals, and the cost of purifying pure tin is unbearable, which is completely different from the nature of "acid-free".

吾妻思萌

Azuma Simeng published on 2023-5-4 17:55 Acid-free means acid-free, literally. [/quote] Teacher, I'm going off topic~ Acid-free should mean no acid added, but I really need to check the details...

Strictly speaking, it also includes "salt", strong acid and weak base salt. As for "lead-free", it is impossible to be absolutely lead-free, because tin ore itself contains a certain amount of lead and other metals, and the cost of purifying pure tin is unbearable, which is completely different from the nature of "acid-free".

Oh ~ so lead is not added, but naturally contained. The purification process and price are too expensive, so it is suppressed to a very low percentage. Acid may be added, which makes sense

chunyang

Azuma Simeng posted on 2023-5-5 09:12 Teacher, I am going off topic~ Acid-free should mean no acid is added, but I really need to check the details...[/quote] Strictly speaking, it also includes "...

Yes, one is actively added and the other is artificially removed, they are fundamentally different.