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This paper explicitly points out that the problems related to humidity in printed circuit board. This is an essay about any type of printed circuit boards the influence of water in the precise articles. From material fusion

by:Rigao      2020-03-28
Rigid/flexible printed circuit board components, cables, box components or wiring harness PCB components made of various types of materials, the materials in full compliance with all major global industry strong mechanical and electrical performance of the electronic products used in the required properties. It requires high frequency, low impedance, compact, durable, high tensile strength, low weight, multi-function, temperature control or resistance to humidity, PCB is divided into single layer, double layer or multilayer, depending on the complexity of circuit. In PCB manufacturing in the initial stage should pay attention to all the major problem, humidity or humidity is in the process of PCB create space is the main factor for the electronic and mechanical failure. Water how to cause great trouble in printed circuit boards? Through in epoxy glass presoak, diffusion in the PCB in the process of storage, the absorption, moisture can form all kinds of defects in the PCB components. The wet method in the process of PCB manufacturing process time, exists in micro cracks or can form a family in the resin interface. Due to high temperature and steam pressure and the lead-free PCB assembly parallel, thus causes the moisture absorption. As the printed circuit board in the adhesive and cohesive failure delamination or cracking, moisture can make metal migration, which leads to low impedance path of dimensional stability change. With the loss of the glass transition temperature, such as the increase of dielectric constant technical more damage, it can lead to high speed and travel time delay circuit switch. Is the main effect of the moisture from the PCB, it reduces the metallization, laminating, resistance welding membrane and the quality of the PCB manufacturing process. Because of the influence of the moisture, the limit of the thermal stress with the loss of the glass transition temperature and excessive. Sometimes it can lead to serious short circuit, leading to water out, cause ion corrosion. PCB components in the hygroscopicity of other common properties include flame retardant or layered, increase ( DF) Dissipation factor and ( 第纳尔 Dielectric constant and the thermal stress on the plated through hole and copper oxide. Reduce the moisture in PCB manufacturing methods: regardless of PCB manufacturing use simple or complex technology, PCB engineering there are many operations require wet process and remove residual moisture. Raw materials used in the PCB manufacturing needs in the process of PCB assembly in the storage, handling and protection during the cope with stress. Here at the different stages of the PCB operation control a brief guide: 1. Laminated laminate is the dehydration step in PCB manufacturing, because of the core and presoak materials stacked together, the layer of adhesive in the laminate. Control in the process of laminating temperature is the main factor, and used time and heating rate. Sometimes dry degree is low, take measures to reduce the degree of vacuum, to reduce the probability of absorbing moisture absorption of interior space. Therefore, in the use gloves when handling presoak is a good way to control the degree of moisture. This reduces the cross contamination. No corrosion of humidity indicator CARDS should be flexible, so that when needed to solve the humidity level. Laminate washing period should be short, and effectively stored in a controlled environment, which helps to prevent the moisture bag formed in the laminate. 2. Laminating process and after PCB assembly in the manufacture of PCB drilling, photographic imaging and etching after operation, the capture in wet process of moisture absorption rate is higher. Silk screen printing and curing solder mask baking is after processing steps, to ease the entrainment of moisture. By minimizing the steps to keep the time interval between even keen to manage storage conditions, which are more efficient at lower levels of moisture absorption. By ensuring that the early stages of a PCB laminate, circuit board dry enough to help reduce the laminated after the baking operation. In addition, using the high quality of surface treatment to prevent cracks in the process of drilling, and before the hot air solder leveling process through baking to remove residual humidity. Curing time of the moisture content should be considered by decision level, the complexity of PCB manufacturing and PCB surface treatment and circuit board needed to keep enough thickness. Therefore, is very important to understand the latest situation of the effect of the moisture in PCB manufacturing, in order to avoid the fault on the PCB, damage and short circuit, at the same time increase the cost of rework. Now, researchers will introduce more advanced solutions, through the use of environmental protection PCB technology, control moisture elements in every step of the PCB manufacturing, so as to save time, energy and cost.
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