Analysis of the Causes of Insufficient Solder Gloss at SMT Patch

Insufficient solder gloss on a solder joint is caused by several factors. A component can have inadequate solder, it could have been overheated for a long time, or it could have peeled off at the solder joint due to age or excessive heat.

Cold soldering

The problem of insufficient solder gloss in SMT patches is often caused by inadequate soldering. Insufficient solder gloss can weaken solder joints and increase their susceptibility to failure and cracking. Fortunately, there are ways to remedy the problem, including applying more solder or reheating the joints.

Insufficient solder gloss is caused by either insufficient flux or too much heat during soldering. Insufficient wetting can also result from a failure to evenly heat both the pin and the pad or a lack of time for solder to flow. When this happens, a layer of metal oxide can form on the bonded object. In such cases, a repair technique should be used to clean the board and apply the solder evenly to the two components.

PCB oxidation

Insufficient solder gloss at SMT patch may be caused by a number of reasons. One common problem is improper solder paste storage and operation. The solder paste may be too dry or have an expired date. The solder paste may also have a poor viscosity. In addition, the solder paste can become contaminated with tin powder during the patch.

Typically, this problem occurs when PCBs are left unprotected for a long time. Another common cause of poor solder joints is oxidation of the surface mount pad. Oxidation can occur on the surface of the PCB during storage or during shipping. Regardless of the cause of the issue, it is important to take steps to prevent this from happening.

Solder balls

Solder balls are tiny balls of solder which can have serious consequences for the functionality of a circuit board. Small balls can move components off-mark and larger balls can degrade the solder joint quality. Also, they can roll on to other parts of the board, causing shorts and burns. These problems can be avoided by ensuring that the PCB base material is dry before reflowing.

Choosing the proper solder paste to use during soldering is a key element in minimizing the risk of solder balls. Using the right paste can greatly reduce the chances of having to rework a board. A slow preheat rate will allow the solder to spread evenly throughout the surface and prevent the formation of solder balls.

Excess solder

Excess solder gloss in SMT patch processes is often caused by a combination of factors. The first is a low preheating temperature, which will affect the appearance of the solder joint. The second is the presence of solder residue. The latter can make the solder joint appear dull or even numb.

Soldering paste smearing on the stencil is another common cause. If the paste has not reflowed properly, the excess solder can flow and obscure the solder joint connection. To remove excess solder, use a solder sucker, a solder wick, or a hot iron tip.

Miswelding

Solder joints with insufficient gloss can be a result of miswelding. The solder may have poor wetting, be dark or non-reflective, or be too rough to look good. The underlying cause is that the solder was not heated sufficiently to reach a high enough temperature for the solder to melt completely.

Solder paste fails to do its soldering job because it is not properly mixed or stored. The paste may not be completely re-dissolved in the solder bath, and the tin powder may spill out during the soldering process. Another cause is that the solder paste may have an expired date. A seventh possible cause of insufficient solder gloss at an SMT patch is a result of the production technology used by the solder paste supplier.

Solder voids

Solder voids in SMT patches can negatively impact a component’s reliability and functionality. They reduce the solder ball’s cross-section, which reduces the amount of solder that can transfer heat and current. Also, during reflow, small pre-existing voids can merge to form large voids. Ideally, voids should be eliminated or reduced to a manageable level. However, many studies indicate that moderate voids can increase reliability by reducing crack propagation and increasing the solder joint’s height.

Solder voids in SMT patches are not a serious problem if they are infrequently occurring and do not affect reliability. However, their presence in a product signals a need for adjustment in manufacturing parameters. Some factors may contribute to the presence of solder voids in SMT patches, including trapped flux and contaminants on circuit boards. The presence of these voids can be visually detected in X-ray images, where they appear as a lighter spot inside the solder ball.