Solder paste is a mixture of metalsolder powder and flux – the two elements required to successfully solder together two pieces of metal. Much like any other form of solder, such as solder strip or wire, you can get solder paste in Firstly, what is solder paste? It is a mixture of metal solder powder and flux – the two elements required to successfully solder together two pieces of metal.

In this passage, please check and read the content below for more information about solder paste in PCB. If you are going to learn professional knowledge of solder paste in PCB.

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What Is the Basic Information of Solder Paste PCB?

Solder paste enables reliable mass produced electronic assemblies that would require a lot of effort to produce with hand soldering at small pitches (space between pins) difficult to produce by hand. The smallest parts in the picture are 0402 resistors, 0.04″ long by 0.02″ wide.

Much like any other form of solder, such as solder strip or wire, you can get solder paste in different types of alloys including silver and gold. You can also get solder paste that melts at different temperatures (hard, medium, easy). Essentially, solder paste is like any other form of solder you can buy – you just have the added advantage of it being pre-mixed with flux!

What are the advantages of solder paste?

Storing solder paste couldn’t be easier. Our number one tip? Always make sure you refasten the cap of the syringe after each use. This will prevent your solder paste from drying up and becoming unusable. Silver solder paste can, if kept under good conditions, last more than two years. Here are some further steps you can follow to ensure that your solder paste lasts:

Not planning on using your solder paste for quite some time? Remove the needle from the syringe and reattach the plastic lid. You can also put it in a Ziplock bag. That way, there’s less chance of air seeping through the needle and drying out your solder paste. If you’re using silver solder paste a lot and store it away for more regular use, organize your solder paste syringes by their melting temperatures. That means there’s no confusion or fuss as you come to find the right solder paste for your latest project. Is one of your syringe needles clogged? Try soaking it in some warm water to loosen the dry solder paste. And if that doesn’t work, use a thin piece of metal wire to remove the paste completely.

What are the main types of PCB solder paste?

According to the type of environmental protection, solder paste can be divided into two categories: leaded and lead-free.

Leaded solder paste is made of a mixture of flux paste and solder powder. The main components are Sn and Pb. The most commonly used leaded solder paste is Sn63/Pb37.

Lead-free solder paste refers to that with a lead content that reaches the EU standard of less than 1000ppm, and it is mainly composed of tin, silver and copper.

According to the temperatures required for use, it can be divided into: high temperature, normal temperature, and low temperature solder paste.

Generally speaking, solder paste with a melting point lower than 138°C is called low temperature. Its composition is mainly tin-bismuth alloy. The melting point of normal temperature solder paste is between 150-250℃, and the melting point of high temperature solder paste is above 250℃.

What are the structures of PCB solder paste?

Solder paste is mainly composed of flux and solder powder.

The main components and functions of flux:

ACTIVATION: This component mainly plays a role in removing oxidizing substances on the surface of PCB copper film pads and parts welding parts, and at the same time, has the effect of reducing the surface tension of tin and lead.

THIXOTROPIC: This ingredient is mainly used to adjust the viscosity of solder paste and printing performance, and plays a role in preventing tailing and sticking during printing.

RESINS: Mainly increases the adhesion of solder paste, and also protects and prevents PCB from re-oxidation after soldering; this component plays an important role in fixing the parts.

SOLVENT: This ingredient is the solvent of the flux, which plays a role in uniformity and the stirring process of the solder paste, and has a certain impact on the life of the solder paste as well.

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