Originally Published: August 21, 2024
In electronics manufacturing, the slowest process determines the factory's output. Improving another operation may create a local benefit, but improving the true bottleneck unlocks capacity across the entire production flow.
On today's high-speed surface-mount technology (SMT) lines, that constraint increasingly appears after assembly: PCBA production test. As panelization increases the number of printed circuit board assemblies produced during each SMT cycle, conventional sequential test may not scale at the same rate. The result can be a growing backlog of untested panels, delayed defect feedback, added labor and equipment, and greater exposure to rework and scrap.
The short answer: Panelization multiplies PCBA output per SMT cycle, but many test operations still repeat one board at a time. Parallel PCBA testing closes that gap by testing, programming, or handling multiple devices under test simultaneously.
The first step is identifying the actual constraint. Over the years, CheckSum has seen electronics factories limited by programming large memory devices, pick-and-place capacity, functional test, and even depaneling.
The best investment is not always the most expensive equipment upgrade. If a comparatively low-cost process such as depaneling limits output, fixing it may generate a faster payback than adding another high-cost placement machine. What matters is improving the operation that controls total factory throughput.
As components become smaller and devices become more capable, many PCBAs have also become smaller. Manufacturers can place more individual boards into one production panel, and CheckSum now routinely sees 8-up, 10-up, 12-up, and larger panel configurations in high-volume applications.
Denser panels do not necessarily create the same challenge for the upstream SMT process. Solder paste inspection processes the panel. Pick-and-place time is driven primarily by the components and placements on that panel-not simply by the number of individual PCBAs that will later be separated from it.
Production test is different. If eight assembled boards reach test in one panel and the test system processes them sequentially, many operations must be repeated eight times. The SMT line has multiplied board output per cycle, but the downstream test process has not multiplied capacity with it.
That mismatch is how an automated inline test cell-or an off-line test area that is less visible to the line-can become the next manufacturing bottleneck.
Automated PCBA test commonly combines three distinct activities: in-circuit test (ICT), in-system programming (ISP), and board-level functional test (FT or FCT). Each process has different cycle-time drivers.
|
Test process |
Common time drivers |
Parallel approach |
|
In-circuit test (ICT) |
Test count, instrument switching and settling, measurements, and powered test content |
Multi-Core ICT runs test content on multiple PCBAs during the same cycle |
|
In-system programming (ISP) |
File size, interface speed, memory-device limits, and the number of devices |
MultiWriter™ programs multiple devices and DUTs in parallel |
|
Functional test (FT/FCT) |
Product-specific communications, stimulus, dwell time, measurements, and required sequences |
Parallel Functional Test (PFT) executes eligible test content across multiple PCBAs simultaneously |
Software and test-sequence improvements can remove unnecessary time, but many required operations simply take the time defined by the device, interface, measurement, or product specification. When an operation cannot be made meaningfully shorter, the practical way to increase output is to perform more work at the same time.
When the constraint is physically on the SMT line, the production impact is obvious: the line slows to the pace of its longest operation. PCBA test is frequently performed off-line, so the SMT line may continue producing panels even when test cannot keep up.
That can make the bottleneck look like an inventory problem rather than a capacity problem. Common warning signs include:
The clearest capacity analysis compares the required panel takt time with the full test cycle, including automated handling, fixture actuation, ICT, ISP, functional test, and any required data or process steps. Looking only at the fastest individual test measurement can hide the actual constraint.
The objective is not to force every test step to run faster. It is to build a test architecture that scales with the output of panelized production.
CheckSum applies parallelism at four levels:
Together, these technologies can combine automated in-circuit test, in-system programming, and functional test in one production cell while increasing output without simply multiplying the number of systems, fixtures, operators, and square feet of floor space.
Consider a 10-up panel that requires a 15-second LIN communications test on every PCBA.
With a fully sequential approach, the functional-test content alone takes:
10 PCBAs x 15 seconds = 150 seconds per panel
If the test is suitable for full-panel Parallel Functional Test, the same 10 PCBAs can execute that 15-second test simultaneously. Ignoring common handling and switching overhead in both cases, that reduces the functional-test portion from 150 seconds to approximately 15 seconds-a savings of 135 seconds per panel.
The exact result depends on the board, test specification, communications architecture, and fixture design. The example demonstrates the underlying point: parallel test preserves the production benefit of higher-density panels instead of allowing that benefit to become a downstream test backlog.
CheckSum originally developed MultiWriter to solve parallel onboard-programming challenges. Customers then asked for the same throughput advantage in in-circuit and functional test.
That led to Parallel Functional Test, a project-specific platform that can execute many common board-level functional operations across multiple PCBAs simultaneously. Capabilities include communications over CAN, LIN, SPI, JTAG, UART, and other serial buses, along with voltage and current measurements, loads, and power control.
Not every end-of-line test belongs at the panel level. Tests that depend on a finished enclosure, final connector access, or complete product assembly may need to remain at end of line. But moving appropriate functional coverage earlier can reduce end-of-line load, identify defects sooner, and improve production feedback closer to the SMT process.
The goal is not simply the fastest individual ICT measurement, programming step, or functional test. The goal is a complete test flow that meets the required SMT takt time with the appropriate test coverage, automation, traceability, and manufacturing cost.
A CheckSum Free Project Analysis reviews the actual panel configuration, test requirements, programming files, functional-test content, handling time, and production target. The resulting capacity analysis can compare single-panel and dual-panel operation, sequential and simultaneous flows, and the appropriate combination of Multi-Core ICT, MultiWriter ISP, and PFT.
If PCBA test is creating WIP, delaying feedback, or forcing additional systems and labor, the next step is to compare your real test cycle with the line requirement.
When your SMT line is running faster than your test process can keep up, CheckSum delivers the solution.
Our automated test systems and advanced parallel test technologies are engineered for high-volume manufacturers producing panelized PCB assemblies—enabling you to test multiple boards simultaneously, dramatically increase throughput, and eliminate costly WIP bottlenecks.
Don’t let test capacity limit your factory. Contact CheckSum today to schedule a Parallel Test Project Analysis and see how you can increase test throughput, reduce manufacturing costs, eliminate WIP, and keep pace with the fastest SMT production lines.
3 min read
John VanNewkirk : Feb 21, 2025, 3:30:00 PM
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