TOOLING
Engineering a Competitive Made in USA Solution
Backend processes such as routing and coating can be optimized for cost savings. by DAVE McADEN
There is no question a number of countries have manufacturing costs lower than the US. At first glance, the cost differential may make outsourcing in those regions the best solution. When the total costs of logistics, transit time, flexibility and quality of communication are considered, however, the cost differential of a Made in USA solution vs. an offshore or nearshore solution can be small. The engineering team at Electronic Design & Manufacturing, a regional electronics manufacturing services (EMS) provider in Lynchburg, VA, has worked to level that playing field even more.

The engineering analysis starts by mapping the process flow and evaluating the cost drivers in the assembly process. While this level of analysis is routine for high-volume, dedicated line projects within the EMS industry, it isn’t always done thoroughly in midrange projects. This typically happens because companies building those projects lack the engineering resources necessary to develop cost-effective custom automation solutions.

While EDM’s team looks at the traditional areas of cost reduction through design for manufacturability (DfM) during that analysis, there is also a focus on identifying opportunities where production tooling or custom automation could take cost out of process steps that are manual, time-consuming or challenging. In many cases, custom automation can be achieved with open-source hardware. The team considers solutions that involve no design changes, as well as those that may involve redesign.

Solutions typically fit into five categories:

  • Automating a manual process via a custom solution.
  • Reducing process time through a combination of panelization and automation.
  • Redesigning to better utilize blended process technology.
  • Optimizing firmware to reduce the time required for test or a downstream process.
  • Utilizing a custom-tooled solution to reduce manual processing time.

For example, in the case of a consumer products manufacturer wishing to bring a product back from China, the cost driver was a relatively small printed circuit board assembly (PCBA), panelized in a 25-up array. The routing, programming and test process following SMT assembly was labor-intensive if performed as separate process steps in multiple work cells, so the team decided to look at modifying the router to combine all three steps.

The modified router programs and functionally tests all assemblies on the panel (FIGURE 1). The team programmed the router to route only the assemblies passing test. As a result, the operator can perform other tasks while the program/test/route process is in progress. Any assemblies failing test will remain attached to tabs on the panel.

In a different case, a PCBA was part of battery packs used in an intrinsically safe environment. Neither a standard automated conformal coating nor manual spray solution met the cost targets. The engineering team developed an automated dip coating solution for a six-up panel array utilizing a robot arm to provide a controlled, repeatable process.

In the test realm, multi-up bed-of-nails test fixtures have been designed to reduce test time. In one example, a six-up PCBA can be completely programmed and tested in a total of 30 sec., working out to about 5 sec. per unit.

In the case of a PCBA using 18 different through-hole socket pins, the team created a custom odd-form part feeder that used vacuum and compressed air to reliably place the pins during SMT topside placement (FIGURE 2). The stencil design incorporated paste deposition for the pins, and the PCB underwent a standard reflow process, instead of a combination of reflow and selective solder.

Creating test firmware can also enhance test speed. In one case, a product with an operations mode that cycled through multiple lighting features as part of user setup had all inputs/outputs tested in milliseconds via a separate test firmware cycle. In other cases, built-in self-test loopbacks are used to cut test time.

view of a robot and its technology at a work station
Figure 1. This robot automatically programs and tests each of the 25 boards, and positively marks each board that passes.
Custom-tooled solutions are also used to cut manual processing time and ensure a repeatable process. The team prints custom jigs using 3-D printers. For example, one product needed a battery spring soldered on the PCBA. The alignment of the custom-formed spring was critical. The PCBAs were routed into 10-up panels and set in a 3-D printed jig that holds 10 springs in exact position for the soldering step. The process reduced time, while eliminating variation during the placement and soldering process.

Through-hole to the rescue. Sometimes older technology provides better cost-reduction options. In the case of a high-volume thermostat PCB with surface-mount headers, the team recommended a switch to a through-hole header with a pin-in-paste (PiP) reflow process. The surface mount headers were tall, didn’t register during placement and often leaned following reflow. Custom jigs had originally been designed, but the handling time made the process inefficient. The switch to the through-hole PiP process eliminated the need for tooling.

Labeling and packing processes can also benefit from this type of analytical approach.

The team uses automated labeling systems in conjunction with jigs to ensure correct placement. The timing of the process is also important. For example, in a product programmed and tested six-up in a universal test fixture, the team found it worked best to delay the labeling process until the PCBAs were routed. Each unit’s memory stores its MAC address and unique information. At the end of the process, the PCBA is plugged in, and the appropriate information prints on a label.

In a packaging situation, costs were reduced by switching PCBAs from anti-static bags to anti-static trays. The project volume was approximately 100,000 units per year, so even a relatively small time difference between time to bag vs. time to place in a tray increased labor cost. The switch to trays not only lowered labor cost, it created stackable packaging that was more convenient for the customer to work with in its receiving process.

It is important to note this type of effort requires a strong EMS-OEM partnership approach. The OEM should have a genuine willingness to consider all ideas for cost improvement and take a total cost of ownership (TCO) approach to evaluating the proposed solution. In some cases, a redesign effort may deliver the best long-term outcome.

view of custom odd-form part feeder
Figure 2. To cost-effectively assemble a PCBA with 18 different through-hole socket pins, EDM created a custom odd-form part feeder that utilizes vacuum and compressed air to place the pins during SMT topside placement.
view of custom odd-form part feeder
Figure 2. To cost-effectively assemble a PCBA with 18 different through-hole socket pins, EDM created a custom odd-form part feeder that utilizes vacuum and compressed air to place the pins during SMT topside placement.
In a packaging situation, costs were reduced by switching PCBAs from anti-static bags to anti-static trays. The project volume was approximately 100,000 units per year, so even a relatively small time difference between time to bag vs. time to place in a tray increased labor cost. The switch to trays not only lowered labor cost, it created stackable packaging that was more convenient for the customer to work with in its receiving process.

It is important to note this type of effort requires a strong EMS-OEM partnership approach. The OEM should have a genuine willingness to consider all ideas for cost improvement and take a total cost of ownership (TCO) approach to evaluating the proposed solution. In some cases, a redesign effort may deliver the best long-term outcome.

DAVE McADEN is chief technical officer at Electronic Design & Manufacturing (edmva.com); dmcaden@edmva.com.