Need for Electrical Testing
Costs of Tests
Don’t Get Caught in the Loop
We live in a world that would regress to the 1800s without the evolution of PCBAs and component circuitry. Think of an email converting back to a letter and taking upwards of 2 weeks or more before you received it. It is quite evident that without PCBAs and component circuitry this world could not function. Because we have these capabilities, we can receive information in a split second, we are able to conduct business on a global scale and we are able to exceed our abilities to treat conditions, diseases, and other abnormalities with evolutionary medical devices.
With so much capability in our hands, advancement of those capabilities became progress and a curse. Advancement requires tighter specifications, more functionality, which results in increasing complexity, added cost due to more components added to the PCB. Then add a big word like miniaturization to this mix and limited access for testing increasingly smaller components becomes a big issue.
With the miniaturization of passive and complex devices, the need to electrically test these components at a high degree of test coverage becomes a necessity in raising the trust of the OEM to know their product is functioning to specifications.
To resolve the miniaturization issue, industry trends are moving toward simple placement of the passive and complex components without the need for electrically testing. The industry believes that the company that created the component would have tested the component thoroughly so that the need to test the component after it leaves the company’s facility would not be required. The issue with this statement is unless companies are going to require their Supply Chain Management and Buyers to procure the most expensive components created by these component companies that have tested the expensive component thoroughly. Then No Problem. However, we require two circumstances: one we require our contract manufacturers to create a lower-cost product in a shorter span. Secondly, we require our Supply Chain Management and Buyers to procure cheaper and cheaper materials and components from the same component manufacturer, which would have these components, but there is no guarantee these components are tested, or we have our suppliers to find an alternative component that is cheaper but there is no guaranty that component is fully tested. Therefore, if we follow industry trends, contract manufacturers could be simply placing complex devices on PCBs that are not tested and could fail and end up in the hands of the company’s customer.
We live in a world where one technical mistake can destroy a company or make it lose all trust with its customers. Therefore, with all the challenges in the realm of testing, OEMs are not given the luxury of making mistakes.
Costs
With the complexity of circuits dominating the design of new technologies, the need for multiple test methodologies to ensure high test coverage of the PCBA becomes a necessity. However, when you take into consideration the cost of the test, a significant percentage of the cost of the PCBA could be directly related to the test strategies needed to ensure a quality product.
To understand the dynamics of why the cost of the test can evolve into a significant expense, let’s first consider what creates this expense. Then later we can discuss a solution on how to resolve the cost of the test.
As we look at the evolution of tests over the years described in Figure 1, the need to introduce a new test methodology becomes prevalent due to new technological advancements of PCBAs over the years.
In conclusion, the cost of the test increases over time due to the need of introducing a new test methodology. As the number of test methodologies increase, we must consider the increase in the number of process steps to execute each new test strategy. Each new process step adds a new layer to the cost of the test. Let’s consider these steps. The first cost factor is the process costs of multiple tests methods since each test method is a single billable process step at a contract manufacturer; the result is each new step will increase the cost of the test.
After the process step issue is considered, the setup time of each test system being implemented becomes a cost factor, the time to get the test connected, calibrated, and running is an issue regarding the cost of the test.
The next issue is the manual connecting of every connector on the PCBA to the test system to execute the tests on the PCBA. This can increase the time of the test thus making it billable time to be charged by the contract manufacturer. Then disconnect the PCBA from every connector of the test system after the test is complete, subsequently, repeating these steps for every board.
When the PCBA is set up on the test system and the test program is ready to execute, the test program may require manually stepping through each set of tests step to complete the test program. Replacement of tester cables becomes a significant expense to the cost of the test. As cables degrade over time, in addition to, the handling done by the operator of the test, replacement of test cables becomes a necessity. Programming of components can require more setup time and connection and disconnection of the device. In addition, you could be programming multiple different devices.
Furthermore, you could need to program one device twice, once for testing as a functional test, then the second time to load the application.
The next topic to discuss is failures. During the functional test, failures can have a huge impact on the cost of the test. Considering labor rates when a failure occurs and needs some form of debugging or failure analysis, a Test Technician with a labor rate of $30.00 an hour could take upwards of 2 weeks to diagnose a failure. If they can’t resolve the failure an Engineer may be needed at the rate of $50.00 an hour to diagnose the failure. So much handling of the PCB can cause more defects due to handling thus increasing the labor rate just to diagnose new defects.
While during this debug or failure analysis, repair equipment may be needed such as oscilloscopes, multimeters, network analyzers, signal generators, other test equipment that will become capital expenditures that would increase the cost of the test.
Another issue to consider is intermittent or false failures. These types of failures often lead to increased labor and labor rates, increased rework, and retest, and increased component costs due to the need to repair or diagnose component failures that may or may not resolve the issue with the PCBA. If the unit is unable to be repaired and no other solution can be found, scrapping the PCBA is the result. Scrap cost account for the PCBA value, labor, materials, and an increase in the production build to ship the required product.
The final issue is the cost of the test escapes. PCBAs that can pass the test system due to a faulty test. This could result in field repairs and increased warranty costs.
In conclusion, the process steps of new test methodologies and the inherited issues of each step can have a significant impact on your bottom line due to the cost of the test.
No-Loop
The worst scenario that could happen to the OEM is this scenario. It is one of the quickest ways to create a scrap buildup. To help you understand this issue, let’s go through the scenario.
First, the OEM has a test developed and installed at the contract manufacturer. The test that is installed has mediocre coverage. A board is tested on this test system and passes the test. The board is stamped and certified as good. The board arrives at the OEM’s facility. Next, the circuit board is placed in the OEM’s inventory. The board is taken out of inventory and placed in their new system to run their new application. Suddenly, a failure is alerted and is diagnosed to be the board they just pulled out of inventory.
The board is placed on an RMA and sent back to the contract manufacturer. The contract manufacturer charges the OEM to retest and repair the board. The contract manufacturer retests the board on the OEM’s installed test system. The board passes again then stamped and certified good again. The board is shipped backed to the OEM and placed in its inventory. The board is taken out of inventory and placed in their new system to run their new application. Suddenly, a failure is alerted and is diagnosed to be the board they just pulled out of inventory. The board is placed on an RMA again and sent back to the contract manufacturer. The contract manufacturer charges the OEM again to retest and repair the board.
The contract manufacturer retests the board on the OEM’s installed test system. The board passes again then stamped and certified good again. The board is shipped backed to the OEM and placed in its inventory. This cycle is repeated until the value of all the OEM’s charges equates to half the value of the board. Then the board is scrapped, and you lose the value of the board and all of the contract manufacturer retest and repair charges.
