A cold chain data logger can look like a relatively compact electronics product from the outside. In manufacturing, however, the finished unit may bring together several different supply chains and processes.
For one cold chain data logger manufacturing program, the customer handled the product structure and injection-molding program through its own suppliers, while Fumax handled PCBA manufacturing and later took on final assembly, ultrasonic welding, packaging and shipment preparation.
The project started in September 2025.
The first PCBA samples were completed in October. By late November, PCBA production was already underway while the enclosure was still being developed. By January, the enclosure, electronics, packaging materials and assembly processes were coming together into finished products.
The complete order covered three SKUs at 5,000 units each, or approximately 15,000 finished units.
What follows is the manufacturing timeline of that program.
The initial manufacturing scope focused on the PCBA for the temperature logger.
The customer remained responsible for the product structure and worked with its own injection-molding supplier on the enclosure and tooling program.
Fumax started preparing the PCBA sample build and the related manufacturing process.
At the same time, one component had already become important to the project schedule.
The product used an e-paper display module, and its lead time could reach approximately six months.
The product also used an EG912U 4G LTE module, with a lead time of around six weeks.
The customer decided to purchase the e-paper displays and EG912U modules separately at an early stage instead of waiting for the final assembly schedule.
The difference in lead time was significant.
While many of the other components could be handled through the normal PCBA purchasing process, the e-paper display needed to be planned much earlier.
The first PCBA samples were completed in October.
This gave the project a working electronic platform while the mechanical side was still being developed.
From this point, several workstreams began moving in parallel.
The customer continued working on the enclosure structure and injection mold.
Fumax continued with PCBA production preparation.
Other items required for the finished product were also being developed at the same time.
These included:
The finished enclosure was not yet at Fumax, but these supporting manufacturing activities did not need to wait for it.
The customer controlled the product structure and injection-molding program through its own supplier.
Fumax did not take over that part of the project.
Instead, both sides continued to progress their respective manufacturing work.
The customer worked through the mold and enclosure development.
Fumax prepared the electronics, supporting production items and the processes required for final assembly.
This separation remained consistent throughout the project.
By the middle to second half of November, the required long-lead electronic modules for the initial production stage had arrived.
With the necessary electronics available, PCBA production could begin.
The enclosure program was still progressing separately.
There was therefore no need to wait for the finished enclosure before starting the electronic production run.
The PCBA could move ahead while the customer continued validating the mechanical side of the product.
As the project moved from samples toward final production, several smaller manufacturing details were also reviewed.
They were not separate projects.
They were simply part of preparing the final product.
The battery connector was reviewed during assembly preparation.
The original connector arrangement was electrically suitable, but the product was relatively thin and the connector could experience mechanical stress during ultrasonic welding.
The team therefore changed the connector to an SMT type with through-hole soldered mechanical retention posts and increased the PCB pad area to improve the connector’s mechanical robustness during ultrasonic welding.
The product also required a waterproof breathable membrane.
Fumax participated in the material selection and verification for the final assembly.
The membrane needed to work with the enclosure and intended application rather than being treated simply as a generic adhesive film.
The battery supplier was also evaluated during the project.
Supplier samples and the relevant product requirements were reviewed as part of the overall product preparation.
Once the customer received the mold trial samples, the enclosure structure could be checked before the final injection run.
Fumax also used the available enclosure samples to verify the ultrasonic welding tooling.
This allowed the enclosure and the welding process to be considered together before final assembly started.
The product’s functional test process was developed around its actual requirements.
The customer defined the product functions, while Fumax assisted in turning those requirements into a practical PCBA functional test procedure for production.
The team also discussed product identification and QR code handling.
Instead of relying entirely on a laboratory-style process in which a finished device is built first and paired individually afterward, a reverse QR code pairing approach was considered so that product identity could be established in a more production-oriented sequence.
By the end of December, the PCBA production was largely complete.
The project had reached an intermediate point where the electronics were nearly ready while the mechanical side was still being finalized.
The customer had received mold trial samples for structural verification.
At the same time, Fumax was using the samples to verify the ultrasonic welding tooling.
The two workstreams were progressing around the same final product without requiring either side to complete the entire project before the other could move forward.
By early January, the main enclosure structure had been finalized.
The customer could proceed with formal injection molding.
At the same time, Fumax finalized the production versions of the packaging materials and product documentation.
The suppliers that had already been identified for these items could then move into volume production.
The production scope included:
The ultrasonic welding tooling had also progressed through its verification stage.
The project had now moved beyond a PCBA program.
The remaining work was about bringing the different manufactured elements together into a finished product.
By late January, the major production elements were available for final assembly.
The finished-product process included:
Two of the three SKUs shared essentially the same components and assembly flow.
The main difference was the battery thickness, which resulted in a slightly thicker enclosure for one variant. The remaining manufacturing process was largely shared.
The e-paper supply had two stages.
For the first 1,000 finished units, the e-paper displays came from inventory that the customer had secured earlier in the project.
That early purchase was important because the display had a lead time of approximately six months.
Once the other major production elements were ready, Fumax used the customer’s existing e-paper inventory for the first finished-product build.
With the Lunar New Year approaching, the first 1,000 finished units were delivered before the holiday so the customer had finished products available for its downstream commitments.
The complete order covered:
3 SKUs × 5,000 units = approximately 15,000 finished products.
The remaining production used e-paper displays from later supplier orders.
Rather than waiting for the supplier to complete and ship the full remaining quantity in one batch, Fumax continued following up with the supplier and requested split deliveries.
The objective was simple: allow the displays to arrive in smaller batches so production could continue as the material became available.
This was different from treating the e-paper order as a single delivery event.
The material was linked to the production schedule.
As each batch arrived, it could be used in the corresponding production run.
After the Lunar New Year holiday, production resumed.
Approximately two weeks later, the remaining finished products were completed and delivered.
The first 1,000 units had used the customer’s earlier e-paper inventory.
The remaining production used the later e-paper purchases as they arrived in batches.
By the end of the program, Fumax’s scope covered much more than PCB assembly.
The customer continued to control:
Fumax handled:
The result was not simply a completed PCBA.
The finished output was a packaged product ready for the customer’s next logistics step.
The customer continued with the product structure and injection-molding program, while Fumax handled the electronics, final assembly and related manufacturing processes.
The two workstreams came together when the finished products entered final assembly.
The overall timeline was relatively straightforward:
September 2025
Project started.
October 2025
PCBA samples completed; enclosure development and long-lead component procurement continued.
November 2025
PCBA production started once the required electronic modules were available.
December 2025
PCBA was largely completed; enclosure trial samples and ultrasonic welding tooling were being verified.
Early January 2026
Final enclosure, packaging and product documentation were finalized; injection molding and packaging production moved forward.
Late January 2026
The major production elements came together for final assembly, with the first 1,000 finished units delivered before the Lunar New Year.
After the Lunar New Year
Remaining e-paper displays arrived in batches, production continued, and the remaining finished products were completed and delivered in approximately two weeks.
The project started as a PCBA manufacturing program.
It ended with approximately 15,000 finished cold chain data loggers, with the customer managing its own product structure and molding supply chain, and Fumax handling the electronics, final assembly and associated manufacturing processes.
