Common Printed Circuit Board Failures & How to Avoid Them.
As the primary way to connect different components to one another through a complex array of circuits, Printed Circuit Board Assemblies are an integral part in many electrical devices today. Despite their universal usefulness and indispensability to electrical designs, PCB Assemblies are known to fail. Indeed, their complex designs and the intricate manufacturing process that is required to make them make PCB Assemblies prone to failure. This is why working with a highly qualified, certified and experienced PCB manufacturer is critical.
With this in mind, this post will take a look at the first three common reasons that PCB Assemblies fail. In our next post, we’ll look at the remaining common reasons for failure.
As you read this, keep in mind that most of these errors can be avoided. Expertise in the manufacturing process and a knowledge and awareness of failure issues goes a long way in preventing the issues that lead to PCB failure.
Here are the first three common reasons that PCBs fail:
- Plating Voids
An important step in PCB manufacturing involves applying a layer of copper to the surface of the PCB material and along the walls of the holes in the board through an electroplating process. This process deposits a thin layer of copper onto the circuit board in a process called deposition. Often, the deposition process is imperfect resulting in voids in the plating. These plating voids can prevent electrical current from passing through the holes in the PCB, which results in a defective product.
There are several reasons that plating voids occur – all which can be avoided by working with an experienced PCB provider. Typically, the plating process does not result in an evenly coated board due to a) contamination of the coating material b) air bubbles caught in the material c) inadequate cleaning of holes and d) insufficient catalyzation of the copper material in the deposition process.
- Acid Traps
Acid traps commonly occur at places where acute angles occur in a circuit. These angles trap acid during the PCB etching process, which allows acid to build up in the nook of the angle. This, in turn, causes the acid to remain in the corner for a longer period of time than intended, which in turn causes the acid to compromise the connection. This makes the circuit defective, which hampers the overall effectiveness and reliability of the electrical device.
Acid traps can be avoided by utilizing a design process that prevents acute angles from being used in the manufacturing of the PCB.
- Missing Solder Mask Between Pads
In order to insulate the copper traces from accidental contact with other metals, solder or conductive bits, a solder mask is applied to the top of the circuit board’s copper layer. The solder mask also acts as a barrier between the copper and the environment, leading to less corrosion. The pads are the portions of metal left exposed by the solder board.
If the solder mask is partially or completely absent between the pads, more copper is exposed than necessary. This can result in solder bridges forming accidentally between circuit traces during assembly. This, in turn, can result in an electrical short and an overall failure of the circuit board.
As with acid traps, missing solder mask is typically caused by a design oversight. A better PCB manufacturer will have a series of checks that helps prevent design errors.
In our next post, we’ll take a look at some additional reasons that PCB Assemblies fail – and more importantly, how they can be avoided.
About the Company:
ADCO Circuits offers electronic design and PCB assembly services to aerospace/military, telecommunications, automotive, industrial/commercial, wireless and medical equipment markets. They are an ISO 9001, TS 16949 and AS 9100 certified. Their personnel is trained to IPC J-STD-001 Class 3 and IPC-A-610 class 3 qualifications. They also have the latest equipment and technology, and advanced information and quality systems to support all of their electronic manufacturing services.