Know the differences in one-off startup services, and what each entails.
One of the most frequent questions I am asked at the beginning of a job is, “What are the NRE/tooling charges and what do I get for them?” Let’s take a moment to review the difference between non-recurring engineering and tooling. I believe doing this will not only provide better insight as to what these costs entail, but
also a better understanding of what it takes to build a flex circuit.
Most buyers understand NRE and tooling costs are a given and a requirement to manufacture. NRE can be best described as virtual tools, consisting of design and programming for a specific flex circuit. Tooling, on the other hand, typically involves a physical item such as a fixture or a punch. Both are dedicated to a specific model or part and not for general production use.
Drilling. Drilling can often require both NRE and physical tooling. The base material is typically drilled to a dedicated pattern, requiring drafting time to generate a drill program. Costs are usually small, rarely requiring a hard tool. The one exception would be covers. Often a cover may require a non-circular opening, in which case a hard-tool punch and die may be used. The key to controlling costs here is to analyze the number of parts being built and the likely life of the project, and then select the most economical approach. A hard-tool will cost more short-term but may have economic advantage in the long view. It’s a surprise to many, but covers are often punched, as the gain in production throughput often pays for the increased tooling cost.
Printing. Not usually a significant expenditure, printing can be handled two ways. LDI (laser direct imaging) requires nothing more than print programs, all virtual. LDI is rapidly replacing the need for expensive negatives that require regular replacement. That said, in certain situations a physical negative can be a cheaper option for etch patterns with wide trace/conductor widths. Laser-imaging large planes on a long-running job is not an efficient use of machine time. As with drilling, actual production equipment time should be considered before choosing your tooling.
Trim. This may be the single most costly item in a tooling list. This is also an area where careful upfront design can provide relief. In essence, the tighter the tolerances of the final dimensions, the higher the NRE/tooling charges. The choice between laser trim programs (NRE) or hard-tools will be driven by initial order quantities or long-term production planning. Laser trim NRE/cost is similar for any part, regardless of complexity. This cannot be said for hard tooling. Trim tolerance tooling can range from a simple steel ruled die (trim tolerance of +/-0.015", or 0.4mm) to a hard-tool punch and die for tighter tolerance requirements (+/-0.004" or 0.1mm).
Testing. Here again we have virtual and hardware options. Order quantity typically drives tooling choice. Fixturing for test can be expensive, but there are several lower-cost options. Flying probe testing is just as it sounds: Two or four probes rotate around the panel, testing continuity and insulation resistance. No fixed tooling is required, but NRE is required to create the programs. Suitable for short-run jobs, machine time can be rather high. Dedicated fixturing such as a “bed of nails” or custom pinned fixture performs much faster tests but requires a physical piece of hardware. Probably the most expensive electrical test would be functionally testing a fully assembled board with active components, which requires programming and dedicated fixturing.
Assembly. There is more to assembly than running parts through a solder wave or reflow oven. Pick-and-place equipment requires NRE for programming component placement. We also require hard tooling in the form of dedicated stencils for screen-printing paste.
Other less common tools such as forming fixtures or potting molds may be required. Typically these tools can be rather complex and require significant NRE for setup and costly machining of the actual tools.
In conclusion, I believe a good part of the confusion surrounding NRE and tooling costs stems from the failure of the manufacturer to provide an itemized list of what goes into such charges. Don’t be afraid to ask for a breakdown of these charges, as this will make you better informed as to what you are actually buying. The savvy buyer understands the need for NRE and tooling but also understands they need to get everything they pay for.