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Top 5 Design Mistakes Affecting PCB Assembly

Posted by Laura Austin on Tue, Sep 25, 2012 @ 07:00 AM

Whether manufacturing for a large multinational tech company or a small electronicspcb assembly company, PCB assembly can be riddled with numerous challenges. Effective assembly requires smooth collaboration between designers, fabricators and manufacturers in order to deliver a high quality circuit board to the market. Mistakes made in design can hold grave consequences to the whole organization, especially where the design failures result in substandard products reaching the market.

The mistakes can be both technical design flaws or operational flaws in the controls put in place in the assembly process. Below are the top five mistakes that you should look out for in PCB assembly:

1. Flex-Cracking
On the technical side, flex-cracking refers to excessive bending of the PCB under a ceramic chip capacitor. The ceramic chip capacitor cannot withstand excessive stress due to its brittle nature. For adequate electrical performance, some printed circuit boards will require large capacitors. Stress on the capacitor can result from accidental dropping or placement of excessive weight on it at any stage of PCB assembly. The type of ceramic chip capacitor that you use in the design stage should be able to handle the stress of assembly and it should not easily crack. You could respond to issues on flex-cracking by using a shorter capacitor or you could replace the capacitor with a smaller unit which has the same capacitance and voltage. 

pcb2. Failure to Adequately Gauge the Performance Environment
One of the most common mistake made by PCB designers is failing to cater for the environment in which the board will operate during the design stage. Some companies will exclude evaluation of the environment as a cost-cutting measure and designers may even be required to closely consider material costs in their designs.
Environmental factors such as: temperature, humidity and even forces such as G-force act on the PCB on a constant basis. If the materials used and the design specifications in terms of size and ability to handle these conditions are not adequate, the resulting circuit board will always fail. Depending on where it is placed, such failure could be catastrophic to the company.

3. Inadequate Communications
PCB assembly will often involve a number of participants. There is the designers, the fabricators and the Electronic Manufacturing Services (EMS) provider. It is often the case that the design-house outsources manufacturing to a different company for business reasons such as lower costs and economies of scale. The different participants need to be in constant communication for smooth delivery of quality products. Mistakes such as failure by the designers to send the preliminary component placement with the assembly house in the initial stages could greatly affect the delivery times. Each company schedules its work toinadequate communication create the most profits for their organization and communication ensures that none of the participants suffers from the other's policies.

4. Lack of Design Reviews
For companies that do not have well defined rules on the flow of work from initial product assembly specification, through design to delivery of the final product, there may be problems in design reviews. Whether the PCB is custom made for a particular client or for the mass market, having the client or your marketing personnel present during these reviews guarantees that the design does not veer away from what the client and the marketers had in mind when specifying the product. Design reviews should be incorporated as part of quality control procedures.

5. Lack of Design Back-ups 
A very common mistake in any type of design work is failing to back-up the copies of your work. Imagine working for months on a new product and then loosing all your work due to a computer crashing. Every organization should implement data back-ups as part of the PCB assembly process. Even designers who work from home should back-up their copies on a spare drive to save themselves the trouble of having to redo the design from scratch. You could also explore safe online back-up options.

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Topics: pcb assembly, PCB, technical design, design review, flex cracking, ceramic chip capacitor, performance environment, inadequate communication, EMS provider, design back up