PCBs Manufacturing - The Most Detailed Introduction(Helpful)
PCBs Manufacturing standard stands for Institute for Printed Circuits, currently known as Association Connecting Electronics Industries It was found in 1975 for setting the standards for bare PCBs and finished PCB assemblies.
The IPC classes for PCBs manufacturing are known as IPC Class-I, Class-II, Class-III and Class-III/A. It is obvious that class-I is the basic of PCB manufacturing quality.
As well as the Class-III/A the strictest. All three classes belong to the IPC-6011 standard. The major difference between classes is their level of qualification.
2.IPC Manufacturing standard
Below is a brief introduction to the different classes:
Class-I PCBs are in the “Limited Life Expectancy” group. Or the electronics assemblies. That are expected to be used in the low-reliability environment.
These PCBs are used in the general electronic products, circuits and gadgets. Such as where the function of the product is sufficient to accept it. An LED light, flashlight, TV remote etc. They are examples of Class-I PCBs.
Class-II PCBs are in the "reliability products category". But reliability is not considered critical. These types of PCBs are used in dedicated products. Such as personal computers, laptops, tablets, smartphones etc.
Class-III PCBs are highly reliable products. It does not compromise over reliable operation of the product. The examples are electro-medical equipment, military equipment, electronic monitoring parts of automotives etc.
This is another type of PCBs for which the manufacturing and inspection criteria are strictest. Their main applications are aerospace, military airborne systems and missile systems.
2.IPC Manufacturing standard
These classes actually define the level of inspection. As well as acceptance of the user. In general, the manufacturing requirements of all the PCBs are approximately same. But require tighter tolerances for inspection. That eventually result to enhanced product reliability. The parameters are controlled throughout the manufacturing process and final inspection.
The faults if occur in any of the produced items. They ensured traceable and if noticed that PCB may be destroyed. This practice makes sure that all of the PCBs produced are 'fault free'. And comply with the tolerances specified by the respective class.
Generally, any manufacturer can claim. That he makes PCBs of class-II or III. But the coupons and the certificates provided for each PCB are verified. They were verified by another third party laboratory. So that certifies the reality about claimed class.
Because to manufacture qualify and certify the manufacturing of each PCB is the sole responsibility of the manufacturer.
So it is upon the manufacturer. That he does manage to qualify each the PCB for respective class. Either he makes more than requested PCBs and destroys the unqualified PCBs. Or makes every product with controlling the features up to his maximum and class category.
Fig. 1:- Class-II vs Class-III PCBs
Fig. 2:- PCB inspection stage for class-II,class-III
Fig. 3:- A comparison and list of IPC Manufacturing standard manufactured PCBs. Inspection parameters