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Precautions Before Placing SMT Manufacturing Order

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Published by Pinsheng Electronics Co., Ltd March 11,2020

Handing over the SMT manufacturing to the professional assembly house doesn't mean there is nothing to do with you, electronics manufacturing is a very specific work, we will ask the clients to provide the necessary data before delegating the SMT manufacturing work to us.

 

There are certainly many things you can do to lead the SMT manufacturing process to better output, I listed 10 of them as follows. 

 

1. Protect the parts from wet

Plastic does absorb moisture, which probably causes the chip package to burst open in high-temperature SMT manufacturing. If you want to purchase components yourself and send them to get soldered, there are two tips for you.

  • First, order the parts when needed, do not buy them too early, and keep the package sealed.
  • Notify the SMT contract manufacturing company that the parts may be wet, and ask them to dry before SMT manufacturing.

 

2. The circuit board must be painted with solder resist

A few people may prefer bare-copper PCBs, which is not a problem when assembling by hand, because you can observe and adjust the amount of solder with your eyes. However, in automatic SMT manufacturing, a stencil is used to apply solder and the circuit board passes through a reflow oven, the solder will spread to the exposed copper foil, which may make the solder on the pads insufficient to establish a reliable connection.

Actually, the circuit boards with solder mask are not much more expensive than bare-copper boards, but it can improve the reliability of your electronics. Besides, colorful solder masks can also make your layout stand out.

 

3. Screen printing is indispensable

Obviously, informative screen printing is useful for SMT manufacturing, which helps to locate each component accurately, tell apart their  Plus-n-Minus. Even If you don't want a circuit board with so much information about your design, you still need to mark it somewhere and tell the SMT contract manufacturing company to pay attention to.

PCB screen printing

 

4. Keep up with SMT manufacturing trends

One of the easiest ways to ensure that you can build a circuit board by hand is to employe THT components totally, but it will limit your layout and make many new technologies impossible. Many of the latest and most functional parts are just ultra-small SMD devices, such as polymer battery chargers, wireless components, accelerometers, and some of the latest microcontrollers.

The PCB supplier are always the ones who keep up with new trends. So if you prefer to include new technology in your electronics, just turn your layout from THT components to SMDs.

 

5. Forget Via-in-Pad (VIP)

In dense layout, the pin pitch of BGA chips is relatively very small, while available spacing for set through-holes is seldom, for which, a new process is to drill via holes on the BGA pads, it might solve the difficulties in layout design, but what I want to say is just forgetting it when you desire a better quality SMT manufacturing. Because VIP is not suitable for automated SMT manufacturing, the solder probably flows through those holes and runs to the back of the circuit board, which will eventually cause short circuits and the parts will fall off because they are not fully connected to the pads.

Via-in-Pad

 

6. Double-check the bill of materials (BOM)

Professional SMT manufacturing is the last step to turn your ideas and related information into physical circuit boards. Unfortunately, we currently do not have a pipeline that directly connects the production line with the brain. The data file is the message transmission pipeline, in which the bill of materials (BOM) is one of the most critical parts. EMS companies do not know your intention in the selection of components, they can't deliver the highest efficient unless you include the accurate instructions in the BOM.

 

7. Ready for alternatives

Speaking of alternatives ... this will always be a good idea, especially now, the components market is facing serious parts shortages, especially multilayer ceramic capacitors (MLCC). Be sure to list alternatives for fear for the parts you originally chose are no longer be available.

 

8. Double-check all components' pads

Small SMDs require very accurate solder volume. The only way to ensure their accuracy is to carefully read the datasheet of the specific parts and confirm that the positions and shapes of each pad you draw meet the part manufacturer's recommendations.

 

9. Ready for communication

Many engineers maybe not good at communicating, but you need to talk to your SMT manufacturing plant and be prepared to respond quickly to any problems. Electronics manufacturing requires clarity and specific, simulating ambiguity as your enemy. When your SMT manufacturing plant asks you any questions, please reply as soon as possible.

 

10. Time to Act

Not long ago, the tools and services necessary to manufacture electronic products were so complicated and expensive. For amateur DIY enthusiasts or makers, it is almost impossible to turn a project based on personal hobbies into a small business. But nowadays all of those have changed, hardware innovation trends are coming back, while it's something that everyone can get it!

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