Four main points are a basic skill for the engineer ,However ,many engineers design some complicated PCB circuit carefully and deliberately,but neglected some points for some simple PCB board which resulted in some problems and let the PCB damaged seriously in the process of transforming PCB circuit drawing into PCB product even with perfect circuit drawing . so in order to improve the work efficiency and reduce the quality risk for helping our engineers ,these points should be concerned carefully in the design process of PCB board
1. Heating ventilation system design with the PCB
In the process of designing the heating ventilation system , it mainly includes cooling solution and how to select the heating ventilation components and referring to the consideration of swelling rate of components. currently . there are many heating ventilation solutions : heating ventilation with PCB it’self . adding heating conductive plates etc .
1.In the traditional PCB designing process . as the PCB Board mainly apply copper clad/Epoxy glass cloth base material or phenolic resin glass cloth base material and Paper base copper clad sheet.due to it’s excellent electricity conductive and manufacturing performance .but it’s heating conduct performance are very poor ,currently many components installed on the surface of QFP ,BGA in the process of designing . heating produced by those components will directly conduct to the PCB board . therefore the most efficiently method to solve this problem is to improve the heating ventilation ability of the PCB layer which contacts the components directly . and drain the heating out through the PCB board .
　
When there are some few components with high temperature , Heating conductive tube or heating ventilator can be added on these components of PCB board to low the temperature . fan can be even considerated when the temperature still can not be lowed .but when there are many components which can product much more heating , a bigger ventilator cap can be directly added on the surface of components . let it contact every components fully on the PCB board .for some special case , it even needs apply the water cooling method to low the temperature .
　
　 2.Components choice and lay-out for the PCB design .
For the PCB design , components selection is a inevitable job for all engineers . each component’s specification can be not the same . even for the same product which produced by the same company also has the possibility with different specification . so master components features and specification is a necessary job to know all the information and application characteristics of components from the supplier . and know the if it can affect the PCB design or not .
　
Also PCB layout is also important . for some components which would product large heating , calculation job should be done before the layout . because for the PCB board when large amount of heating accumulated on the PCB and it can deformed the PCB insulation layers and incinerate the PCB board in worsen condition .
　
PCB size is the foremost factor to be consideration for the layout design of the PCB board ,when the PCB size is too big , the printing circuit line will be long , the resistance will increased in such situation . cost also increased .,when the PCB size is too small , the heating ventilation performance is not good ,and neighboring circuit line can intervene with each other . ideal layout for all components should be done based on components functions and it’s size
　　3.Inspection and test design with the PCB board
Inspection and test technology for the PCB board will play the roles of improve the product quality and reliability ,low the cost in product life . so find a proper design on how to check the components performance will be necessary job .
As the trend that electronic product will go to smaller and smaller as the time goes by . components installation distance will become narrower and narrower . installation density is be bigger and bigger . the components position can allowed for the inspection will be less . printing PCB components inspection test will be difficult more and more . so when for the initial design of the PCB boards ,many factors should be considered such as : the electrical conditions and machinically condition of the test for suitable electronic tester should be consider in advance .
　　
　　4.MSL of PCB design
There are usually with 8 grades 1、2、2a、3、4、5、5a、6 of MSL： Moisture Sensitive Level .special management should be done for some components which has strict moisture requirements . for some temperature sensitive components . the temperature management for those components should be also considered in storage .when in the baking process . different components will be baked in different temperature for components with temperature requirements . for some moisture sensitive components ,12H should not be exceeded for storage conditions . components should be stored at vacuum and dry place for storage for those moisture sensitive components at room temperature .