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    The Complete Understanding Of Solder Paste


    If you have ever seen an electrical mount board, you must have seen various circuits attached to it. But how are these circuits attached in the first place? It is where the solder paste finds its use. It is applied to the surface of mount boards before we place any chip over it. Then we place the chip over it and subject the solder paste to reflow of infra-red radiations. Through this, the paste melts, and soldered joints are formed. This process is very helpful as it saves a lot of time.

    It is mainly used during the PCB assembly process, and the process becomes very much easy and time sufficient just due to the virtue of solder paste.

    Solder Paste

    Which material is used in making Solder Paste?

    Now the solder paste can be used for a variety of purposes. It can be used for large PCB assemblies as well as small prototypes. But the question here is, what is solder paste made up of. You pick any paste on this planet, and you will see that almost all of them are a mixture of two or more substances. The same is the case with the solder paste.

    The solder paste is the concoction of very small solder spheres pulverized in the form of solder flux. Now the components of that mixture have changed over time; in the past, solder paste used to be a mixture of tin and lead. But as the lead is harmful, so now the solder paste is made lead-free. In many cases, is 97.7 percent tin and 0.3 percent copper. In other cases, some other materials like gold are also used.


    There are many advantages of solder paste in modern engineering. But some of them are as follows.

    Use of syringe

    The use of a syringe applies solder paste. It helps you cover even the minor details of the circuit and helps you design the board as you want it to be. So the solder paste won't spread here and there on the mount boards, causing the problem for the worker.


    Some people also use solder strips or solder wires in place of the solder paste. But they can be very frustrating. Frustration starts when you cut them into tiny pieces, put them on the board, and blow the hot air over them. Due to the strike of hot air, these minute particles get blown away. And it can be very bad if you are not able to find them later. But solder paste is not like that. It stays in its place with much consistency; hence you can do anything at any place on the board according to your work plan. Solder paste will not disappoint you.

    But the use of solder strips becomes important in some cases. It is because they produce strong solder joints. And they will be able to withstand any heat. Solder paste joints area bit weaker comparatively.

    How the solder paste is applied

    Solder paste is very easy to use if you want to learn the skill of soldering. Following are the steps that will give you a little knit and grit about the solder paste.

    Uncapping the Syringe

    First of all, you need to remove the cap of the syringe. The syringe is one of the most valuable points of a solder paste. It makes the soldering precise and according to the needs. Here, the cap of the syringe should not be thrown away as it would be used after the soldering is finished.

    Cleanliness of the Metal

    Now you need to check the metal over which soldering is supposed to be done. It should be free of any dirt or grease because any dirt can make the soldering process more hectic and time-consuming than normal.

    Join should be Flux

    Now when you start soldering, then you should be looking at all the joints. It would be best if you observed whether they are flux or not. If it is not flux, then the joint is weak. And if it is flux, then it means that the solder joint is strong. The light should not be passing through the joint.

     Apply the Right Amount

    You need to put the right amount of solder on the mount board. The syringe plunger controls this amount. At first, you may release more or less solder from the syringe. But by the time you will have an idea of how much pressure you are supposed to apply on the plunger to eject the right amount of the paste.

    Wipe the extra

    Now, if some extra solder paste in some area, you are supposed to wipe it out. Similarly, if there is less solder paste in some areas, you should put more solder paste there. You should develop a habit of doing it along the soldering process and not at the very end.

     Apply the Heat

    Now when you have applied the solder paste over all the vital points, the next step is heating the solder paste. The heating must be done circularly, and the heat should be concentrated completely on the solder paste joint area.

    Cross check

    Suppose you think that soldering you just did is not quite good. Then you still don't need to worry. You can easily put some more solder paste and repeat the same process that we have already discussed above.

    Ways to Store

    Storing the solder paste can be tricky if you are using it for the very first time. Many new users throw the cap away when they use the solder paste for the first time. People should not do this. It would be best if you kept the cap with yourself. After finishing the soldering task, you are supposed to put the cap back on the syringe. It will help the solder paste not get dried up as it will be unusable.


    Solder paste is a good choice if you are working over any circuit. This article has covered some of the main points you needed to know about the solder paste. For More Information, Contact Us Today!

    Solder Paste


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