Transition from Domestic Prototype to Off Shore Production for Flex Circuits

A smooth domestic to off shore transition

Designing a flex to be prototyped domestically? No, problem. Designing a rigid flex for production off shore? Got it. Designing a part that will be prototyped domestically with a seamless transition to off shore production? That can be a little more challenging.  We have probably all been there. The prototypes are needed on a very tight delivery schedule and are built domestically. The testing is complete and the same files are sent to an off shore manufacturer for the production build. The order is placed and suddenly, the engineering questions start coming in. Can the materials be changed? Can the hole size or pad size be altered to improve manufacturability? These common questions now require the time and effort to evaluate and ultimately the time and effort to complete the rev spin before production product can be released. We sat down with Ashley Luxton of Graphic, PLC to learn his recommendations to minimize these disruptions . Our discussion focused on the importance of supplier selection, items that are universal and key areas that have more significant variation. A link to our discussion is included here.

Supplier Selection – Choose your supplier carefully and consider the different options available. There are manufacturers that own both domestic and off shore facilities, there are domestic manufacturers that partner with off shore facilities and there are manufacturers that work only domestically or only off shore.

When working with a manufacturer that has both domestic and off shore capabilities, it is critical to communicate with them early in the design process. The fabricator, understanding both the domestic and off shore preferences and capabilities, will be happy to make recommendations for material selection, panel utilization, and also how to maximize yields for the production volumes.

A domestic supplier that partners with an off shore manufacturer will be able to offer this same type of guidance. Due diligence is recommended. Most domestic manufacturers that partner with an off shore supplier do so to offer their customers a full service option. Significant effort is put into learning their partner’s technical capabilities, material preferences and operations. The lines of communication between the facilities are well established.

There are also domestic suppliers that purchase product from off shore suppliers to support a full range of volume requirements for their customers but have not put the extra effort into learning and understanding the details of their off shore partners technical capabilities. This model provides the customer with volume production from off shore, but may not be the best solution when looking for design guidance to ensure a smooth domestic to off shore transition.

When working with two independent facilities, take the time to fully understand the off-shore suppliers capabilities and material preferences and then apply that criteria to the domestic prototype design.

Universal Criteria: Whether your PCB’s are being manufactured domestically or off shore, certain things are universal. Quality specifications such as IPC Class, FAIR requirements, and testing requirements do not change. Some of these specifications may not be as critical at the prototype stage and could be waived, but the interpretation of the specification will be consistent.

Designing to maximize yields may not be as critical with a prototype order, but with the higher volumes typically associated with off shore production, expected yields should be considered. There are universal criteria for maximized yields. Increasing holes sizes, pad sizes, line width and space will all improve yields at the manufacturer and have a direct impact on cost.

Acceptance of X-outs should also be considered. Allowing X-outs in your delivered array will have a direct impact on cost. If X-outs are not allowed, both domestic and off shore manufacturers will factor in the yield loss associated with scrapping any good pieces in an array that has an x-out. If X-outs are not allowed, this should be clearly communicated to avoid any misunderstanding.

Significant Variation: Preferred materials can vary significantly between domestic and off shore manufacturing. This preference is typically a function of material availability and cost.   Logically, off shore suppliers will prefer to use materials that are produced locally. These materials are more readily available, with lower transportation costs. Most off shore suppliers will also use the materials that are more common in the US, but pricing will be higher and lead-time longer.

Be careful not to over specify materials. Referencing the appropriate IPC slash sheet, rather than the specific material, allows more flexibility for the supplier.   This flexibility will result in lower cost and shorter lead-time. If more control is required for material selection, using an “approved list” of materials that has been tested and approved is another option that allows the manufacturer flexibility to use their more preferred materials, while giving the designer more control of materials being used.

Another aspect that varies significantly is panel utilization. Domestically, the most common panel size is 18” x 24” with 16” x 22” of useable space for the manufacturer and it is most cost effective to design the part or the array to best fit that space.   Off shore manufacturers have much more flexibility with their panel sizes, use many different panel sizes to best utilize material and generally work with larger panels. Off shore it is more critical to design the array to best utilize the material within the array and overall array size has much less of a cost impact.

To recap, when looking for the smoothest transition from domestic prototype to off shore production manufacturing, research suppliers and select a supplier that can demonstrate their knowledge of the off shore facility’s technical capabilities, material preferences and clearly have a streamlined form of communication. Quality and testing specs are universal and should transfer from one facility to the other with no issue but special attention should be given to controlled impedance, materials and panel utilization, as these can vary significantly between domestic and off shore manufacturing facilities. A smooth transition from domestic prototypes to off shore production does not need to be difficult, but it does need to be well planned.

Please contact us for more information!  www.omnipcb.com

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