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Solder joint – one basic lesson about PCB soldering

Solder joint - the comprehensive guidance about it in PCB soldering

Solder joint makes an important component of any electronics construction. Meantime PCB soldering is a very important process in PCB production and PCBA. Without PCB welding, components cannot be fixed and form a complete circuit board. If solder joints are ineffective, your equipment will just not work. Therefore, making good solder joints is of utmost importance. Let’s dive into it.

What is the solder joint?

What-is-the-solder-jointBasically, a solder joint is a material-closed bond or joint of two metals. Meanwhile, soldering involves joining two pieces using a melted component. It is capable of sealing links and is different from welding. Welding is quite different from soldering because it involves melting the pieces that need to be joined. Meanwhile, solder is the material is used to form a joint.

What is a good solder joint?

How do you know if a solder joint is good enough? Well, a good solder joint has some specific features. For instance, it will have a shiny finish to it and it will not have excessive solder. In addition to it, the contour of the solder will be concave around the joint. These are some properties of a good solder joint.

When there is excessive solder on the joint, it can deteriorate the joint and there is always a possibility that it could touch another track on a PCB and lead to a short circuit.

What are the types of soldering joints?

Generally, there are different types of solder joints. Some of them are:
What-are-the-types-of-soldering-jointsButt Joint: A butt joint involves joining two pieces of metals with their ends against each other. It is necessary for the ends to be flat and clean to ensure that the solder adheres properly. Usually, this joint does not have much strength and it cannot be used for major projects.

Strapped Butt Joint: Typically, when a supportive metal is soldered under or over the existing butt joint, it takes the form of a strapped butt joint. Due to the added support, the butt joint becomes stronger.

Scarf Joint: This type of a joint is similar to a butt joint. However, it involves the ends cut on a diagonal. It results in a better and stronger joint. In addition, when pieces are cut in a unique stair-step pattern, it is recognized as a step joint.

Lap Joint: When it comes to the lap joint, it is usually created when two pieces tend to overlap each other, and solder is used and applied between them. Actually, the strength of such a joint generally depends on the extent of overlap. When there is an increase in the overlapped area, it results in a stronger soldered joint.

Side Seam Joint: A side seam joint is better and stronger than a traditional lap joint, and the extra strength is primarily because of its design. For starters, one piece is folded over which gives three layers to the joint.

Pipe Joint: A pipe joint is used for creating a tight seal. In order to create a pipe joint, a heat gun is utilized for melting the solder and sealing the joint.

What are the factors will affect good soldered joints in connectors?

What-are-the-factors-will-affect-good-soldered-joints-in-connectorsThere are several factors that affect and influence a good soldered joint in a connector. Temperature is an important factor because it enables metals to combine under a hot eutectic. If the right temperature is not maintained during heating, the solder strength will be insignificant and the joint will not hold.

Another important factor is solder quality. Even though there is no universal alloy, silver alloy solders are being used extensively for making joints. The health of the solder tip is also important because the maintenance of a healthy tip is necessary for the visual quality of the connection. Soldering tips are usually coated with quite a unique material. Therefore, the tip should be maintained.

How do you make a solder joint?

First of all, heat the joint. You need to heat both the component pin and the solder pad. Now, touch the end of the solder to the required joint to make sure that it contacts both the component lead and the solder pad. You need to ensure that it melts and flows smoothly onto the pad and the pin.

Continue heating the solder and let it flow into the joint. Make sure that it fills the hole and flows smoothly. With the addition of enough solder, remove the iron and let it cool. In the end, just trim the lead using diagonal cutters.

How do you make solder joint stronger?

It is possible to make stronger solder joints by adding adequate solder volumes during the process of bonding. In case you pour insufficient solder, the joint will become unreliable and weak.

What’s the material of solder joint

The solder joint of the circuit board is solder. Soldering paste: It is an important industrial raw material for connecting electronic components in welding lines, widely used in electronic industry, home appliance manufacturing, automobile manufacturing, maintenance industry and daily life. It is an indispensable material in the electronic industry.

Common soldering materials include tin lead alloy soldering tin, antimony added soldering paste, cadmium added soldering paste, silver added soldering tin and copper added soldering paste. The linear solder used in standard welding operations is called rosin cored solder wire or solder wire. PCB Flux is added to the solder, which is composed of rosin and a small amount of active agent.

What are the process requirements for PCB solder joint?

1. The mechanical strength of the welding point shall be sufficient
2. Reliable soldering to ensure conductivity
3. The surface of solder joints on the PCB light plate shall be free of burrs, voids and tin dragging
4. There is no abnormal sample on the surface of the solder joints on the PCB light plate, otherwise it may cause false solder joints and false solder joints, resulting in unreliable SMT patch solder joints.
5. The amount of soldering tin shall be appropriate, neither too much nor too little.

What’s a solder joint failure?

A solder joint failure occurs when the joint is not made properly. Due to it, the joint does not work as it is expected and it even leads to a short circuit in severe situations.

FAQ about solder joint

FAQ about solder joint

How do you check solder joints?

While there are many methods you can use to check solder joints, micro-sectioning is perhaps the simplest and most widely used method. It involves taking a 2D slice from the sample and evaluating the degree of solder spread and wetting.

Do solder joints fail?

Yes, it is rather common for solder joints to fail. It commonly occurs when solder joints are not good enough to perform the required function. For instance, it is possible that excessive solder might be used and it can result in a solder joint failure.

What is a wet soldered joint?

Typically, a wet soldered joint is a type of joint that involves the creation of a metallurgical bond between the substrate and the solder.

How do you fix a broken solder joint?

First of all, you need to identify why the solder joint is not working. It might be due to insufficient or excessive solder on the surface. You can either add more solder iron to make it work or you can just scrap it and begin anew. In this manner, you can fix the broken solder joint and make it work.
Solder joint


This article helps us understand solder joints. If you also want to know about more about PCB soldering, you can find related information articles in our website : PCB flux, SMT solder paste, solder mask, and so on. If you are looking for an experienced and professional PCBA company, please contact us. IBE is a one-stop PCBA service provider, which can provide PCB design, component procurement, PCB assembly, packaging, transportation and other services.



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