Global market pressures on the PCB industry have forced the development of automated fabrication methods. To guarantee competitive positioning in producing more complex circuits in shorter cycle times at lower cost requires manufactures to consider automation throughout the entire production process. Cost-effective automation must facilitate technology advancements while improving process controls and reducing labor content.
In addition to the obvious fabrication processes, the electrical test (E.T.) function is certainly worthy of automation. Until recently, automated E.T. equipment applications were limited to simple PCB circuits. Board handling mechanisms and fixturing technology were typically unsuited for more complex circuit designs. These limitations restricted an acceptable return on investment for automated E.T. equipment to high volume, low tech PCBs. However, recent product introductions from several suppliers have presented the industry with full and partial automation choices, making test automation more viable and affordable for all PCB manufacturers. Full automation should at least triple the throughput seen with manual operations, and partial automation should at least double manual throughput. Measurable quality and cycle time improvements are seen in such test areas as the elimination of escapes by automated marking of PCBs. Every consideration should be examined in determining the automation option best suited for a manufacturer's products and facility.
The first and foremost consideration is whether or not the PCB manufacturer will actually benefit from automating the electrical rest function. That is, can justification for the investment be derived from projected gains in capacity, improved productivity, or quality, and any other criteria deemed valuable to that manufacturer. After this has been established, other important considerations in automated E.T. equipment selections are:
Capability. Full testing automation should include the ability to load, test, "pass," mark, unload, and sort PCBs. Also, a provision for alignment should be available when PCB image-to-tooling misregistration occurs. The ideal automated system should automatically verify each failure to identify false opens, ensuring that every possible passed board is shipped. In regard to board size and thickness, automated decisions are usually made around a specific group of PCB dimensions and should not necessarily provide for every board size and shape. This ensures that a significant portion of product sizes can be accommodated.
Performance/Throughput. An automated system must provide fast, accurate handling and electrical testing of all PCB densities being produced. It should use an inexpensive fixture system that reliably tests both simple and complex circuits at throughput rates significantly higher than manual operations.
Modularity. Separate, compatible automation modules should afford the user the luxury of purchasing total E.T. automation, the option of targeting problematic test ares, or areas which best match an available automation budget. The modules must be retrofittable to existing or planned test systems. Another modularity consideration is the ability to use the modules on any number of like testers, not limiting their use to a specific machine.
The addition of relatively inexpensive loader/sorter modules can increase testing throughput by 2- or 3- fold, without a proportionate increase in E.T. cost.
Setup. The ability to setup automation quickly and efficiently is paramount. Setup for a new PCB part number should be done within fifteen minutes without the use of hand tools. Some available equipment facilitates setup procedures with graphical, on-screen software prompts. The operating software should permit individual part number setups to be saved in the corresponding test program.
Service/Support. Minimizing system downtime is essential to high throughput test operations and maximizing return on automation investment. Minimal downtime is a product of the automation design and ease in both preventive and corrective maintenance. Crucial to this is the nature of the automation hardware. Is it simple? Is it reliable? How many moving parts are involved? Can the fixture and all moving parts be accessed easily or do they require partially dismantling the system? The equipment manufacturer should provide complete service instructions and graphical help screens that assist troubleshooting and normal maintenance, and should offer a complete service organization with local field support, as well as on-line interactive factory support.
Manufacturer's Strength. An often overlooked consideration is the financial and organizational strength and the ability of the equipment manufacturer to provide continuous product support and development. The commitment and application of these resources will dramatically impact the PCB producer's prospects for successfully implementing E.T. automation, and can extend current capabilities and yield future innovative test solutions.
To keep pace with their customers' advancing technology, PCB manufacturers face endless capital expenditure demands. Fortunately, the potential to develop the world class test environment essential to meeting these needs has never been greater or more economical. E.T. automation is now more capable and affordable than ever before. To successfully position themselves in the global marketplace, PCB manufactures must focus on the E.T. process to prevent any volume and technology bottlenecks that could impede growth. Understanding today's automation test modules and considering every option is essential in selecting the optimum E.T. automation for competing in today's global marketplace.