Tips to Choose a PCB Design Vendor | Sierra Circuits

Say your business is looking for a new printed circuit board—anything from the layout for a wearable device or a heads-up display, to fabrication and assembly of a prototype. No matter the case, precise manufacturing and quick turnaround times, as well as a reliable single point of support throughout the entire process, are essential to getting what you need, when you need it. Hence, finding a capable and reliable PCB design vendor is crucial. What happens between the time you first conceive of the PCB to the moment it arrives at your office, ready for use?

Choig supply professional and honest service.

Expectations for fulfilment are understandably high in a world in which so many other products and services are available near-instantly, on-demand, from sellers like Amazon and couriers such as FedEx. With PCBs, much of the procurement work—e.g., putting together a bill of materials (BOM) and submitting its components list to a vendor—happens between conception and actual ordering. Accordingly, there is the need to remove any potential barrier to getting a rapid response from your PCB partner once you have something concrete in mind.

Let’s dive into what the concept-to-ordering progression often entails. With its steps in mind, we can see what an ideal process for getting a top-notch PCB would look like, with design, purchasing, manufacturing and delivery all optimized for rapid turnaround. We will look at one possible example, among many, for a PCB in a hardware device.

1. Designing the PCB Layout

Going from a blueprint to an actual PCB layout requires additional technical attention to design details. A good PCB design vendor will keep a close eye on metrics such as how close the traces are to each other, whether there are sufficient airflow and heat dissipation throughout the board, the overall package size, and general resistance to environmental issues such as vibrations and possible bending, although this last factor relates to only flexible and rigid-flex PCBs.

Today’s products can be quite complex to design, hence focus falls upon the more “interesting” aspects of the product, like the FPGAs or MCUs. But the fact is unless the board is designed correctly in the first place, you are going to run into issues sooner or later. It is also very important for you to know whether the PCB design vendor you have chosen is adequately equipped to design your board. Particularly a few details should be discussed extensively before you can zero down upon the design.

PCB stack-up: this becomes quite a trade-off between fabrication processes and layer count to achieve the desired reliability, yield, and cost targets.

Via types: This is also an aspect that is quite important, if your design vendors use too many types of vias in a single PCB, alert! The best design will have a minimum of the different types of vias.

Are the via aspect ratios correct? Make a note to a high of an aspect ratio can really pull down the reliability of PTH boards. In that case, the use of microvias is the best option. Also, it reduces the length of the traces, hence making better signal integrity. And what about the component placement, crosstalk budgets, layer allocation?

It is very important to know if your designer has a DFM team. This will ensure the finished design can actually be manufactured.

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11 Chapters - 96 Pages - 90 Minute Read

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• Annular rings: avoid drill breakouts
• Vias: optimize your design
• Trace width and space: follow the best practices
• Solder mask and silkscreen: get the must-knows

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2. Breakout Strategy

The breakout strategy of a board is also quite an indispensable part of designing. Your designer must first ensure you can breakout and route all of the signals on high-pin-count devices. When you breakout, you basically apply a fanout solution. You route traces from those fanouts to the perimeter of the device prior to the general routing of the PCB. This will also affect the stack-up plan.

3. Signal Integrity and Power Integrity

In today’s miniature era, maintain strong signal integrity and power integrity has become quite a hustle. Though usually an engineer is supposed to take into account aspects such as the signal rise and fall times, track lengths and characteristic impedances, and the drive strength and slew rates of the drivers and terminations. But to ensure the best of performance signal integrity simulations on the PCB should be performed both pre and post layout.

Again, for power integrity, both the DC and AC performance of the power distribution network is of vital importance.

4. Templates

PCB designers are persistently put to test, addressing the issues of shrinking electronic items through engineering boards with the most efficient positioning of components. That is expected to do the necessary functionality while meeting the specifications of the item to contain the board. Therefore, ensure your PCB designer has time-proven constraint templates available. Sizing and placement of critical elements, including minimum and maximum tolerances, electrical demands including power needs, and impedance factors, required components, all combine to generate a primary set of constraints for the PCB design. This can shape up the design of new boards or upgrades to existing PCBs with considerably very fewer errors.

5. Materials and Components

Sometimes, we think materials and components are the fabricator’s headache and hence, do not enquire about the designers about the materials. Consider during the layout phase the materials and components you have in mind for your board. Ensure your PCB designer has chosen the optimal materials and components for your board, and also the role the designed board plays to those items’ strengths.

6. Component Placement

Another fundamental query of yours should be about the order of the component placement. It is one of the most critical design guidelines. The recommended order is connectors, then power circuits, then precision circuits, then critical circuits and then the rest of the elements.

7. Power, Ground and Signal Traces

Next on our list are the power, ground, and signal trace considerations. Tracking designs, pad and hole dimensions, etc., is very important and you must know about these factors before you lay your concept to the PCB design team.

8. Thermal Reliefs

Thermal issues can impact many different parts of the PCB design process.

Boards are getting smaller whereas the current passing through the traces is getting higher. The consequence? A high temperature and heat generation. Ensure your PCB design has sufficient space around all components that may get hot. The more heat they create, the more area they will need to cool off. Note the placement of the critical components not to place, they are not supposed to be near heat sources. Your board is multi-layered? Or may you have assemblies with high copper content? If so, you may need to include cooling fans, heat sinks, and thermal reliefs, which are critical for wave soldering.

9. PCB Testing

Throughout the PCB design process, as well as the rest of the PCB manufacturing process, you should continuously check your work. Catching problems early on will help minimize their impact and reduce the costs of fixing them. Hence, choose a PCB design vendor who will do the testing. Two common tests your design should go through are the electrical rules check and the design rules check.

10. The Best PCB Manufacturer in the USA is a One-Stop Shop

Initial designs may still require some modifications to ensure that they are manufacturable. For example, the board may need to be tweaked so that it can meet impedance requirements without becoming too thin and too difficult to assemble reliably. Or, its flex layers may be better off placed inside the rigid PCB layers of the proposed stack-up, so as to avoid any manufacturing errors.

Having a single point of contact for these types of issues is paramount for eliminating the confusion and communications errors that can arise when changes are made. Moreover, working with a nearby partner further simplifies matters and ensures that the overall time from conception and prototyping to accurate ordering and fulfilment is quick.

Nonetheless, whoever you choose, make sure to have constant communication to make yourself and your concept heard, with a hint of business of course.

If you want to learn more, please visit our website one stop pcb desing service.

Check out these steps for designing with the end goal of getting a working PCB prototype back from your manufacturer the first time.

We all want our PCB prototypes to get done as fast and as cheap as possible, but sometimes this just doesn’t happen. After all, when you start a new design and focus all of your time on your circuit design or component selection, then you have little time left over for your PCB layout. But in the world of PCB manufacturing, when it’s time to turn an idea into a board, then the layout process is what matters most.

So what’s the key to designing a PCB that gets you a working prototype back right the first time? We’ve got our top 10 design decisions below to make it happen.

Table of Contents

• 1. Be mindful of your component placement
• 2. Define your trace widths before designing
• 3. Keep your electromagnetic interference in check
• 4. Orient your power and ground planes
• 5. Add accurate silkscreen marking
• 6. Avoid mixing leaded and lead-free components
• 7. Double Check For Solder Mask Between Pads
• 8. Leave Clearance Between Your Copper and Board Edge
• 9. Identify heating issues before they start
• 10. Double-check for acute angles on your traces
• Good boards, good times

1. Be mindful of your component placement

When placing components on your PCB layout, you always need to be thinking in the back of your mind how your parts will be soldered. Are you working with SMT components that need to run through a wave solder machine (edited)? Then you’ll want to orient all of your parts of a similar type in the same direction.

We also recommend placing all of your surface mount components on the same side of your board to avoid multiple spins through the soldering equipment (edited). And try keeping all of your through-hole parts on the top side of your board to minimize how many steps are required to assemble your parts by hand.

2. Define your trace widths before designing

Before you even begin laying down parts or routing nets, you need to know how wide your traces need to be to carry their required current. As a general guideline, we recommend having your traces set at 0.010” for low current analog and digital signals.

If you’re working with traces that will be pumping out more than 0.3 amps, then make your traces wider. And you don’t need to do all of these manual calculations by hand to determine trace widths. Just use a freely available trace width calculator as part of your pre-design prep work.

3. Keep your electromagnetic interference in check

We’ve all likely worked on circuit boards with large voltages and know that electromagnetic interference can mess up your low-voltage and current control circuits. To reduce the impact of interference, we recommend keeping your power ground and control ground planes separate for each power supply stage.

If you do happen to place your ground plane in the middle of your layer stackup, then also be sure to add an impedance path. This will reduce the chance of your power circuit interfering with other components on your board.

4. Orient your power and ground planes

We always recommend adding your power and ground planes in the internal layers of your board. The placement of these layers will help to keep your board more sturdy and ensure that it doesn’t bend during the component placement process. For Integrated Circuits (ICs), we also recommend using a common set of power rails that have wider trace widths to handle the increased heat that will be pouring through the copper.

5. Add accurate silkscreen marking

We always recommend identifying components on your board in a simple and easy-to-understand manner that makes the component placement and orientation process as painless as possible. For example, adding helpful symbols that show where the anode and cathode ends of a diode are inserted will make your life a whole lot easier.

6. Avoid mixing leaded and lead-free components

There are a bunch of older components out there still in use that don’t have a lead-free option. While you might be tempted to toss one of these in with your newer lead-free parts, think again. Both lead and lead-free components have very different heat requirements, especially for RoHS-certified parts.

If you do need to mix lead and lead-free components, then consider putting something like a lead-free BGA on a leaded board, as opposed to a leaded chip on a lead-free board. The latter of these two scenarios will often lead to a board that overheats and evaporates all of its flux, creating an overly compressed and damaged PCB.

7. Double Check For Solder Mask Between Pads

It’s a common mistake to forget to add a solder mask layer between your pads. Maybe you pulled your design settings from a larger PCB over to a smaller one, and now you have pad holes that are too large. It happens.

Whatever the reason, always double-check before sending your design off to your manufacturer that all of your pads have a layer of solder mask between them. This will help to fight against the risk of bridging and corrosion. When your design files do land in your manufacturer’s hands, they’ll also likely perform a complete DFM check to help spot any solder mask you might have missed.

8. Leave Clearance Between Your Copper and Board Edge

Whenever you design a PCB, we always recommend leaving a small amount of clearance between the edge of your board and any copper planes or traces. The last thing you want is for your PCB to get trimmed out of its panel during manufacturing and your copper to get trimmed as well. If this happens, the exposed copper will open your board to short circuits.

Set yourself up with some design rules in your DRC before you ever start your design process to define copper-to-edge or plate-to-edge clearances. If you keep a clearance of at least 50 mils, you should be safe. Always check with your manufacturer ahead of time to see what clearance requirements they recommend.

9. Identify heating issues before they start

If you’ve ever had the performance of a circuit degrade over time, then you know how costly heat issues can be in a manufactured product. To help keep your heating issues in check, always know what components on your board will pump out the most heat. You can find this information in any datasheet by looking for the Thermal Resistance ratings and their accompanying guidelines.

10. Double-check for acute angles on your traces

Most of us designers these days know to avoid making acute angles in our traces, but they can still slip through the cracks, especially when two traces join. During the PCB etching process, the presence of acute angles can lead to an acid buildup, which eats away at the copper and makes the circuit defective down the road.

When your routing process is complete, always review all of your traces, especially segments where two traces connect, for any acute angles. And during your routing process, opt for 45-degree trace angles instead of 90.

Good boards, good times

Want your PCB prototype back fast? Then, take the time to incorporate the 10 design decisions above in your own PCB design workflow. If you do, then you’ll be well on your way towards getting your prototype PCB back right the first time without wasting any money in the process. When choosing a manufacturer to work with for your PCB prototype, always be on the lookout for one that provides a complete DFM check as part of their offering. It’s always nice to have a second pair of eyes.

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