There’s something unique about unexpectedly getting a package marked “handle with care.” It could be something valuable, but there’s also the mystery of whether the package was really handled safely.
Many times, I’ve found broken glass, leaking bottles, or other shipping mishaps when I’ve opened a mistreated package. And while a broken knick-knack can be a disappointing loss, the financial impact of a fractured or intermittent operating circuit board due to mishandling can be much worse.
Even though PCBs are built to be tough to survive the heat and pressure of manufacturing and the stress of their operation, a circuit board must still be handled with care. The substrate of a PCB can fracture, its electronic components can break, be contaminated, and is vulnerable to static electricity discharges. For longevity and the best performance of the circuit board, it must be handled with the greatest of care. Here, we will look at some potential problems associated with rough treatment and the rules for handling printed circuit boards to avoid these undesirable consequences.
Why PCB Handling Rules are Essential
A chain is only as strong as its weakest link, and the same principle applies to a printed circuit board. The common PCB is a copper-clad laminate with a hardened fiberglass resin core. Although this structure is robust, and its installed components are soldered firmly in place, a PCB still has many vulnerabilities that can be exploited through mishandling:
- ESD (Electrostatic Discharge): Circuit board components are designed to operate within a specified range of voltage that is carefully calculated for their circuitry. On the other hand, static electricity can be created through a simple and unexpected action such as opening a plastic bag or rubbing articles of clothing together. If a circuit board is exposed to these unintended discharges of static electricity, the tolerance of some of the components can be exceeded, causing damage to those parts.
- Physical damage: Although the circuit board is built to be tough in the application it is designed for, it can still be easily damaged if it is treated too roughly. The board can be broken if subjected to enough impact, like falling off a workbench, and soldered parts can snap off if hit with enough force. Metal traces and pads on the board can lift or crack if the board flexes too much. Even normal manufacturing activities can cause damage if not planned for or executed correctly. For example, de-panelizing a circuit board can crack components and lift metal traces if the manufacturing panel isn’t designed correctly.
- Contamination: Moisture can cause a circuit board’s metal traces and pads to tarnish, and even regular dirt and grime can add to the problem. These contaminants can affect the components’ solderability, causing weak connections or disrupting the manufacturing process.
IPC-1601A is the standard used by the circuit board design and manufacturing industry to specify the correct handling procedures for circuit boards to avoid the problems listed above. Most manufacturers follow these standards explicitly, with many going beyond the requirements to ensure the highest quality in the circuit boards they build. Next, we will look at some of the more essential rules to help you handle your circuit boards with care.
Rules for Handling Printed Circuit Boards During Processing
A circuit board goes through a lot of handling during its production and therefore is vulnerable to mishandling incidents. Based on the problems listed above, here are what manufacturers focus on to protect the boards they are producing:
- ESD: Circuit boards are handled the most during PCB inspection and rework, and therefore all work must be done in properly designated work areas. These areas should be clean and neat with proper ventilation, and technicians should be grounded with a wrist strap connected to the earth-ground.
- Physical handling: Workflows should be set up for lean manufacturing and strategically laid out to minimize the board’s handling. Technicians should wear protective clothing and gloves, and circuit boards should be handled gingerly by their edges. The more automated processes that can be used, the better, as automated inspection equipment (AOI) cuts down on how much the board must be physically handled.
- Moisture: Unassembled PCBs and components should be kept in their protective bags until they are ready to be assembled. Many components have a date code that must be strictly adhered to, regulating how long they can be exposed to open air before risking moisture contamination.
The following dos and don’ts will help provide the best handling protection for circuit boards:
- Protect the board from moisture by keeping it in its protective bag until needed.
- Keep your workstation clean of any materials or liquids that could contaminate the PCB.
- Make sure your workstation is designed to resist static electricity buildup.
- Handle the circuit board by its edges with a secure grip using as little pressure as possible.
- Utilize trays and racks to minimize the physical handling of the circuit board.
However, safe handling of the board is only part of ensuring its protection. It also has to be protected during storage and shipping.
Circuit Board Storage and Shipping
The different materials and processes used for circuit board manufacturing can change how a board is handled and stored. For instance, a board built using a lead-free process to satisfy the European Restriction of Hazardous Substances Directive, or RoHS, must be stored differently from other circuit boards. To prevent the PCB’s immersion silver surface finish from oxidizing, manufacturers will use silver wax paper to help protect these boards.
Manufacturers are also concerned about ESD and will use anti-static bags to protect the finished circuit board. Here is where an advanced PCB contract manufacturer like VSE goes beyond the standard handling requirements used by the rest of the industry and ships their completed circuit boards in shielded padded bags. These bags protect the boards from electrostatic discharge and help provide physical protection for components and other sensitive parts during transportation.