When you buy SMT components, you have several options for how you want the parts packaged. Understanding the manufacturing process will help you make the most economical choice.
As a contract manufacturer, we often work with surface mount technology (SMT) components supplied by our OEM customers. Sometimes buyers select packaging that makes sense from a component cost standpoint but makes manufacturing slower, more complicated, more expensive, and more prone to quality or yield problems.
SMT parts come in several packaging types.
- Reels: Components are fixed in an embossed plastic tape and wound on a reel. Reels usually hold 400-10,000 parts.
- Mini-reels: Some manufacturers offer smaller reels. For a fee, some distributors will break up a manufacturer's standard reel to create mini-reels with a custom number of parts.
- Cut tape: The plastic tape is cut into strips, typically with 10 to several hundred components per strip.
- Trays or tubes: Components are placed in individual compartments in a tray or lined up in a tube. Large components are commonly packaged this way.
- Bulk: Loose parts are placed in a plastic bag. This is common with specialty parts such as high-precision resistors.
Reels are the easiest for manufacturers to use, and they're the obvious choice for high-volume production. They make sense for lower-volume work, as well. For example, a reel of passive components runs about $8. Even if you need only a few hundred resistors, it's more economical to buy a full reel. For these inexpensive components, the cost savings from smaller-volume packaging will be minimal if any.
A mini-reel can be a good option for more expensive parts. Manufacturing processes treat a mini-reel just like a full reel. Your purchase decision can be made purely on availability and component cost.
If a mini-reel is not available, cut tape may seem like a good alternative. But if manufacturing needs 100 parts, don't assume you can order a tape with 100 parts on it. You might get 10 strips with 10 parts each unless you special order continuous cut tape. Even then, SMT machines need a leader or “feed strip” to be inserted into the automated feeder. If there's no leader, the first components on the tape will be wasted. How many depends on the pick-and-place machine. The MyData lines at Z-AXIS waste only a few components. Other machines waste up to 200.
Contract manufacturers can handle cut tape by adding a leader strip, using a special fixture to hold the cut tape inside the machine, or placing the components manually. If the components are quite expensive, this extra handling in production may be worth the extra manufacturing time and cost.
Trays are another alternative to mini-reels, and they are more universally available. They are popular for large parts. They have lower capacity than reels and need to be changed more often, stopping the line if they are changed manually. Tubes also have lower capacity and need changing frequently.
Automated tray changers and multi-tube magazines cut down on the handling and keep the line moving, but because they take up the space of 8-10 reels on the line, they are problematic for boards that have a lot of different part types.
Bulk components are a manufacturer's least desirable option. They have to be placed manually or repackaged into trays for automated placement. Your distributor can package the parts into trays or on tape, and it will charge you a lot less than your contract manufacturer probably will for this same service.
Our pick-and-place lines and production teams are flexible enough so that we can work with any packaging type that our customers supply. You can't assume that all contract manufacturers have this ability. It pays to work with your manufacturing partner and understand how your choice of component packaging affects the manufacturing process, reliability, and cost.