What is a Solder Void?
What is a solder Void?
Solder void is a hot topic for all electronic manufacturers. In short, a solder void refers to a blank space, crack, or emptiness that occurs due to various reasons while manufacturing the solder joints of a printed circuit board. For example, it can get created because of the unavailability or absence of solder pastes at certain places during the development of the joints.
According to the IPC standard for solder voids, a solder void will get evaluated as a deformity if the incremental area containing all voids appears greater than 25% in the x-ray picture.
Type of Solder Voids:
When it comes to the types of solder void, there are a few we can discuss. There are mainly six types of voids that get seen in general. Have a look at them.
- Macro voids: These are the relatively bigger solder voids generated to expand enmeshed gasses inside the solder pastes. The appearance of macro voids (approximately four to twelve mils) is pretty natural during the surface mount process.
- Planar Microvoids: These voids of one to two mils generally get developed due to the failure of Ball Grid Array devices.
- Shrinkage Voids: These voids look more like a crack, presented both on the through-hole solder joints and Ball Grid Array devices. Shrinkage voids are more uneven and extended.
- Intermetallic Microvoids: This type of solder void gets created due to the exposure of the circuit board to high heat, more than 100 degrees for two days and longer.
- Microvia Voids: The Ball Grid Array generally incorporates microvias at the corners. One kind of solder void appears from these joints, which is called a microvia void.
- Pinhole Microvoids: The solder void gets generated between the intermetallic compound sheet and the copper layer.
Factors responsible for Solder Voiding:
Solder voiding is a general phenomenon for almost all printed circuit boards. This is because not all circuit boards encompass a sufficient amount of solder paste while getting manufactured, which causes solder void. Let’s have a look at the major factors responsible for solder voiding.
- The layout of the stencil and reflow form
- Solder paste and layout of the printed circuit board
- The surface finish of the printed circuit board and overall atmosphere
Impact of Solder Voids on Solder Joint Performance:
Having smaller voids is pretty normal for almost all printed circuit boards. But, for some reason, if there is a deadly void or more than one bigger crack, it is a matter of concern. It can have several impacts on the overall quality and performance of the solder joint.
Here are some impacts of solder voids are mentioned below.
- It makes the solder joint less reliable and durable
- Having one or more rough voids can induce solder bridging
- It curtails the thermal conductivity of the solder joint
- If there is a big void in the solder joint, the solder paste tends to stream and gets misplaced at other places during the reflow procedure
- An extreme presence of solder void impedes the electricity transmitting capability of the board
How can you avoid Solder Voiding?
Solder voiding is an unwanted impediment while manufacturing printed circuit boards that should get avoided by the manufacturer. Otherwise, the outcome will not be satisfying. So, here are a few tricks that you can apply to avoid solder voids during the solder joint developing process. Have a quick look at them.
Double up the soak time:
You can increase the soak time to avoid solder void. In addition, expanding the soak time will help drive off the low boiling hazardous components before the reflow process starts.
Increase the temperature:
You can intensify the heat to avoid solder voids in the future. In this way, the volatile substances will get enough time and space to run off before the solder joint starts to solidify.
Diversify the stencil:
Make sure to bring some modifications to the stencil design so that the gas can easily run out and not stay trapped inside the board.
Use a different solder paste:
Always try to use a solder paste during this stage since it has a lower inclination and capability of forming voids and cracks. Also, during this process, you can get your hands on no-clean solder pastes instead of water-soluble solder pastes since no-clean solder paste contains lesser volatile components and does not absorb moisture from the air.
Industry Specifications for Solder Voiding:
According to the IPC standard for solder voids, a solder void will be evaluated as a deformity if all voids’ incremental area appears more significant than 25% in the x-ray picture. Otherwise, it will be counted as a normal solder void, not any defect. They have also given some solutions regarding how to avoid these unwanted solder voids in solder joints, such as understanding the reasons behind the void, computing the proportion of void, governing and deterring voids, and more.
The IPC standard for solder voids says additionally that the present industry evidence shows that solder voids have nothing to do with a circuit board’s durability. In short, the location of the void concerns more than anything else. For instance, if there is a solder void present in the intermetallic layer of a board, the board contains a higher chance of getting damaged with time and environmental impacts.
Call to Action:
These, in short, are all about solder void. Now, when you have collected enough information about solder voids, types of solder voids, a few facts that are responsible for solder voids, the impact of solder voids on solder joint performance, how to avoid the voids, and other related details, hopefully, it will become easier for you to recognize and prevent unnecessary solder voids from the next time. However, if you are still confused, we can help you out. Being in this electronic manufacturing field for a long time, we have years of experience preventing solder voids. So, if you need any help from our side, try to contact us at your early convenience.
