Packaging And Shipping Protection For PCB Shipments
Packaging is the part of the process that protects everything the factory has just built. A board that passes every inspection can still arrive unusable if it was packed without regard for moisture, static or mechanical shock. The cost of the protection is trivial compared with the cost of a rejected shipment.
Good packaging is specific. It depends on the board sensitivity to moisture, on its static sensitivity if components are fitted, on its mass and fragility, and on the transport route. A single generic carton rarely suits a full product range, and the differences are easy to define once the four risks are listed.
What Shipping Damage Looks Like
Damage does not always look like a broken board. Obvious mechanical damage, such as a cracked corner or a gouged edge, is easy to spot. The more common problem is damage that appears later: oxidised pads from moisture exposure, latent electrostatic damage in a component, or a hairline crack that opens during the first thermal cycle.
Because those failures are delayed, they are often attributed to the wrong cause. A pad that refuses to wet may be blamed on the finish supplier when the real cause is a bag that was opened in a humid room and never resealed. Traceability of packaging is part of the traceability of the product. Surface protection applied before packing is described under conformal coating and board protection.
Moisture Barrier Bags And Desiccant
A moisture barrier bag is a laminate of polymer and metal foil that limits the rate at which water vapour passes through it. The measure of that resistance is the water vapour transmission rate, and the low values needed for electronics packaging are only achieved with a foil layer. Plain polyethylene bags do not qualify.
Inside the bag, a desiccant absorbs the moisture that remains after sealing and the moisture that permeates over time. The quantity is calculated from the bag area, the required shelf life and the humidity of the packing environment. Sealing must be complete across the full width of the bag, verified by a visual check for channels and by periodic seal strength testing. How these requirements are agreed with the customer is described under PCB design and fabrication.
Edge Protection And Stacking
Boards are vulnerable at their edges, where the laminate is thin and the outline is exposed. Interleaving with a soft material or using a slotted rack for each board keeps the surfaces apart and prevents edges from rubbing. The rack also fixes the position of the boards, which reduces movement during transport.
Stacking should be limited by weight rather than by carton volume. A carton filled to the top with bare boards concentrates the load on the lowest panel, and flexing from that load can crack a conductor or a solder joint. The maximum stack height should be stated on the packing instruction and be visible to the packer.
Electrostatic Discharge Control
Boards carrying sensitive components must be packed in materials that dissipate static charge rather than insulate it. The standard approach is a shielding bag, metal-in or metal-out, combined with a dissipative rack and a dissipative carton lining. The bag shields the contents from external fields and provides a path for charge to bleed away.
Static control also covers the packing station. Operators wear wrist straps or heel grounders, work surfaces are dissipative, and the station is audited. A shielded bag is not much use if the board is placed in it by a person who has just walked across a carpet in synthetic clothing.
Humidity Indicator Cards And Labels
A humidity indicator is placed inside the bag to show how much moisture the contents have been exposed to. The card changes colour at defined humidity levels, and the reading tells the customer whether the bag remained sealed. Cards are read at three levels in most specifications, and the acceptable level is written into the receiving procedure.
Labels carry the rest of the information: the moisture sensitivity level of the components, the date the bag was sealed, the calculated floor life, and the baking instructions if the indicator shows a problem. Without the label, the customer cannot decide whether the boards need drying before assembly.
Cartons, Pallets And Documentation
The carton and the pallet complete the mechanical protection. Cartons need enough compression strength for the stack height they will see in the warehouse, and pallets need to be dry and free of protruding nails or staples. Shrink wrap holds the load together and keeps rain and dust off the outer layer for a limited time.
Documentation travels with the goods: the packing list, the certificate of conformance, the sensitivity label and any test report the contract requires. A copy should also be retrievable electronically. How the packaging requirement is fixed with the customer is described under PCBA development process.
Process Control and Verification
On a design of this kind, packaging is the item that decides how the rest of the board is arranged. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used. Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design.
The measurements that matter are the repeatable ones: conductor width and spacing, annular ring, finished hole size, plating thickness and surface finish are all verifiable on a coupon that travels with the panel. Running a first article through the same checks as the production panel confirms that the two agree, and that comparison is the cheapest form of process control available at prototype stage.
Process Control and Verification
On a design of this kind, packaging is the item that decides how the rest of the board is arranged. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used. Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design.
Process Control and Verification
On a design of this kind, packaging is the item that decides how the rest of the board is arranged. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used. Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design.
A first article check confirms that the process and the drawing agree on the points listed above, and that the coupon data supports the values used in the design.
Where a measurement falls outside the expected window, the sample is retained so that the cause can be established before the balance of the batch is released.
FAQ
When must boards be baked before assembly? When the humidity indicator shows more moisture than the specification permits, or when the floor life has been exceeded. Baking is defined by the component moisture sensitivity level and must respect the maximum temperature rating.
Can a moisture barrier bag be resealed and reused? It can be resealed once, if the seal area is clean and dry and the bag is not punctured. The desiccant should be replaced, and the seal quality should be checked as carefully as it was on the original packing line.
Is a vacuum pack better than a plain sealed bag? Vacuum packing removes air and reduces the moisture and oxygen available, but it presses the bag against the board edges. Where edges are fragile, a nitrogen purge inside a sealed bag without full vacuum is often the safer choice.
