3 Tips to Keep Your PCB Design on Schedule

PCB design is like chess. You have to plan for the end game.“In order to improve your game, you must study the endgame before everything else. For whereas the endings can be studied and mastered by themselves, the middle game and opening must be studied in relation to the end game.” 

—Jose Raul Capablanca, chess master

There has always been pressure on design teams to deliver on schedule. Nothing is more frustrating than pushing your team to release a PCB design on time and then to find out that your first prototype build will be delayed due to several common, avoidable errors.

Here are some tips to help manage risk and to avoid unnecessary delays:

PCB Design Tip #1 – Select a Supplier Early

Engage your potential suppliers early before your design package is ready for a quote. Ask them explicitly what would help them deliver your PCBA (“Printed Circuit Board Assembly”) on time. By interacting with them early, you’ll get a feel for the level of support you’ll receive in the future.

Setup payment in advance

If the supplier offers credit terms, fill out the credit application in advance. Once you have approved credit with the supplier, it will provide you the flexibility to make changes quickly without having to re-authorize subsequent credit card charges,to  provide additional cash deposits, or to send multiple wire transfers. And, of course, make sure to pay your invoices on time to prevent delays on subsequent orders that may be held up for delinquent payments.

Provide a preferred shipping carrier

If possible, set up your preferred carrier in the supplier’s system. Then there will be no delays waiting for shipping instructions. This may seem obvious, but double check that the billing and shipping addresses are entered correctly, too.

PCB Design Tip #2 – Plan for Parts Management

Long Part Lead Times

During the design phase, it is important to browse online distributors and to take a cursory look at the current stock and standard lead times, especially for single-sourced or unique parts. Begin securing these parts as soon as the architecture is stable. Don’t wait until the BOM (“Bill-of-Material”) is finalized before ordering these parts. Otherwise you may be in for an unpleasant surprise when parts that were available weeks ago will not be back in stock for several months.

Parts Procurement

Clearly, you will want to avoid paying for additional markup on parts if the supplier orders them,  right? However, if you decide to manage the parts yourself, realize that you will be paying for shipping twice: once from the distributor and once to your supplier which may actually cost you more in shipping charges than for low cost parts. Also, you’ll assume the handling liability if your supplier discovers problems during the incoming inspection and you will be responsible for handling any warranty claims with component vendors or shipping providers. Most suppliers order parts daily from distributors so they are able to amortize shipping costs among multiple orders and they likely get better pricing than you can due to their order volume. IMHO, the best approach is to have your supplier secure parts so that the liability rests with the supplier.

Permit substitution for common components

Large suppliers have an existing inventory of common parts, especially passives. If you permit them to substitute for common parts you will likely save additional costs to purchase additional common parts and reduce the risk that your specified parts will delay your build.

Quote PCB fabrication early

Once the layout is mostly complete, prepare a design package for quoting purposes. This enables the PCB (“Printed Circuit Board”) supplier to provide preliminary feedback on your design. This may include highlighting missing information or identifying errors that would prevent the supplier from fabricating the PCB. The longer the turnaround time, the less expensive the PCB fabrication should be. If you can plan for a four-week turn on PCB fab, you will get the best pricing possible. Also, components can be ordered concurrently so that all the material will arrive at the same time.

PCB Design Tip #3 – Plan for Test

Except for the first pass PCBs, you will likely want some level of test for subsequent builds to ensure basic build quality.

Provide a Basic Test Procedure

Yes, it will cost extra. BUT, how disappointing will it be when you discover that  6 out of 10 boards don’t work! Either you’ll have to debug them yourself or send them back for warranty. Most warranties are only going to cover workmanship defects anyways. But, if you provide a basic test procedure, you provide the supplier an opportunity to detect defects and possibly rework the PCBs which will yield more working boards delivered to you.

Test Software

If your PCB design has programmable parts, create a simple test firmware image that can be programmed into the unit. The test firmware should provide an indication to the test technician that confirms that the device is operating properly.

Test Equipment

If your device requires specialized test equipment, check if your supplier can rent it for your project. You should only invest in more advanced test strategies such as flying probe, ICT (“In-Circuit-Test”), and boundary scan once your design is finalized. Otherwise, you’ll end up paying NREs (“Non-Recurring Expenses”) multiple times which may cost hundreds or thousands of dollars.

Summary

Remember, that the first build of your PCB design is just the initial step toward the goal of producing a cost-effective, reliable, and quality product.

Don’t be short-sighted and plan ahead for the end game.