This paper clearly points out the problems related to humidity in printed circuit board. This is an accurate article about reducing the effects of moisture on any type of printed circuit board. From material fusion, PCB layout, prototyping, PCB engineering, assembly through packaging and order delivery stages, attention should be paid to the influence of moisture in PCB manufacturing to avoid damage and other problems with PCB functionality. In addition, give us an insight into the important measures to control humidity levels during lamination, controls implemented during PCB assembly and control storage, packaging and transportation.

Rigid/flexible PRINTED circuit board assemblies, cable bundles, boxed assemblies or Wire bundles PCB assemblies are made from a variety of types of materials that fully match the properties required for strong mechanical and electrical performance in electronics used in all major industries worldwide. It requires high frequency, low impedance, compactness, durability, high tensile strength, low weight, versatility, temperature control or humidity resistance, and the PCB can be single, double or multi-layer, depending on the complexity of the circuit. Of all the serious problems that should be looked out for in the initial stages of PCB manufacturing, humidity or humidity is the major factor that leads to creating room for electronic and mechanical failure in PCB operations.

What is the effect of moisture on PCB

How can moisture cause huge trouble on printed circuit boards?

By being present in epoxy glass prepregs, diffusing in PCBS during storage, and when absorbed, moisture can form various defects in PCB assemblies. The wet process time in PCB manufacturing exists in microcracks or can form a home in the resin interface. Due to the high temperature and steam pressure parallel to the quadcopter configuration in PCB assembly, water absorption is caused.

As adhesive and cohesion failures in printed circuit boards lead to delamination or cracking, moisture can make metal migration possible, leading to a low impedance path for dimensional stability changes. With the decrease of glass transition temperature, the increase of dielectric constant and other technical damage, it will lead to the circuit switching speed reduction and high propagation time delay.

The main effect of moisture in PCBS is that it reduces the quality of metallization, lamination, solder resistance film and PCB manufacturing processes. Due to the influence of moisture, the limit of thermal stress is excessive as the glass transition temperature decreases. Sometimes it can also cause severe short circuits that allow water to enter, leading to ion corrosion. Other common properties of hygroscopic properties in PRINTED circuit board assemblies include flame retardation or lamination, increased dissipation factor (DF) and dielectric constant (DK), thermal stress on plated through holes, and oxidation of copper.

Methods to reduce moisture in PCB manufacturing:

Whether PCB manufacturing uses simple or complex techniques, there are many operations in PCB engineering that require wet processes and removal of residual moisture. Raw materials used in PCB manufacturing need to be protected during storage, handling and stress handling during PCB assembly. The following is a brief guide to implementing control at all stages of PCB operation:

1. laminated

Lamination is the dehydration step in PCB manufacturing because the core and prepreg billet are stacked together to bond the layers to the laminate. The main factors controlled in the lamination process are temperature, elapsed time and heating rate. Sometimes when dryness is low, measures are taken to reduce vacuum to reduce the possibility of internal voids attracting moisture absorption. Therefore, the use of gloves when handling prepregs provides a good control of moisture levels. This reduces cross-contamination. Non-corrosive humidity indicator cards should have the flexibility to resolve humidity levels as needed. Laminates should be washed in short cycles and stored efficiently in a controlled environment, which helps prevent pockets of moisture from forming in the laminates.

2. Post lamination process and PCB assembly

After drilling, photographic imaging, and etching operations in PCB manufacturing, the moisture absorption rate captured in the wet process is higher. Screen printing curing and welding mask baking are processed steps to relieve entrainment moisture. This is more effective in reducing water absorption levels by minimizing the hold time interval between steps and even enthusiastically managing storage conditions. By ensuring that the PCB is sufficiently dry at the early stages of lamination, the board can help reduce post-lamination baking operations. In addition, a high quality finish is used to prevent cracks during drilling and to remove moisture from residues by baking prior to the hot air solder leveling process. Baking time should be maintained by taking into account the determined level of moisture content, the complexity of PCB manufacturing, PCB surface treatment and sufficient thickness required for the board.

Therefore, it is vital to know the latest situation of the effect of moisture in PCB manufacturing to avoid failure, damage and short circuit on the PCB, while increasing the cost of rework. Now, researchers are on the verge of introducing even more advanced solutions that save time, energy and cost by using environmentally friendly PCB technology to control the water element in every step of PCB manufacturing.