Tape Splice Control: Keeping Feeders Running Without Losing Parts
A tape splice joins the end of one reel of components to the start of the next so that the feeder does not have to be reloaded in the middle of a run. It saves a line stop of several minutes and, done carelessly, it introduces a missing or doubled component into the assembly.
The joint is therefore a process step with a specification, not a repair made at the machine. The parameters that matter are where the joint sits, how the carrier tape is aligned, how the cover tape behaves across it and how thick the joint becomes.
Why Splicing Exists and What It Costs
Reloading a feeder means stopping the line, opening the feeder, threading a new tape and re-teaching the pickup position. Splicing removes that stop by letting the tail of the old tape pull the head of the new one through the feeder.
The cost is the risk of the joint itself. A splice that is misaligned, too thick or badly bonded can jam the feeder, and a joint in the wrong place can present a pocket with no component or with two. Both failure modes produce defects that are hard to trace back to the reel, and both are usually blamed on the placement machine before the tape is examined.
Where the Joint Should Sit
The joint is made in the empty section at the end of the old tape, normally 200 to 400 mm before the tape ends, and never across a loaded pocket. Placing it there leaves enough tape to thread the feeder and enough leader on the new reel for the pickup position to be reached.
The leader and trailer lengths of the reels themselves are standardised, typically 400 mm each, and those are the dimensions that make a splice possible without losing components. The conventions are described in the notes on tape and reel packaging.
Carrier Tape Alignment and Pocket Pitch
The two tapes have to be aligned in three directions: the pocket centres have to be on the same pitch line, the tape edges have to be flush, and the sprocket holes have to remain on the same spacing across the joint. A mismatch of half a pitch is enough to make a feeder index incorrectly.
Pitch is fixed by the component size, commonly 2, 4 or 8 mm, and the splice has to preserve it exactly. Where two reels of the same part but different tape thickness are joined, the alignment is more difficult and the joint should be avoided if a matching reel is available. The joint is also kept clear of the last pockets, so that the feeder is not indexing across the splice while it picks, as the standards notes on carrier tape standards explain.
Cover Tape and Peel Force at the Joint
The cover tape has to peel cleanly across the joint at the force the feeder is designed to apply, which is typically between 0.1 and 1.0 N, with most tapes in the range 0.2 to 0.7 N. A joint that doubles the cover tape thickness can exceed the feeder capability and tear.
The splice tape should bond the cover tape without overlapping a pocket, and the peel should be tested by hand across the joint before the reel is loaded. The measurement and its limits are the subject of the notes on cover tape peel force.
Thickness at the Joint and Feeder Interference
The finished joint should be within about 0.1 mm of the carrier tape thickness. A thicker joint lifts the tape in the feeder track, changes the pickup height and can prevent the cover tape from being taken up at the correct angle. The spliced section should also be free of adhesive squeeze-out that grabs the tape guide.
Thickness comes from the splice tape and from any overlap of the carrier tapes. Butt joints with a thin splicing tape are the most reliable, while overlapping the carriers produces a step that no feeder handles gracefully.
Tools and Blocks for a Repeatable Splice
A splicing block holds the two tapes on the correct pitch line while the tape is applied, and it removes most of the variation between operators. The block has to match the tape width, commonly 8, 12, 16 and 24 mm, and it wears, so it is an item to inspect rather than to keep forever.
Consumables have their own specification. The splice tape should be the correct width for the carrier, fresh, and stored so that the adhesive is not contaminated. Dull or improvised tooling is the usual reason a shop has a splice problem it cannot reproduce, which is the same discipline applied to feeder consumables.
Verifying Before the Reel Reaches the Line
Verification is quick. The joint is inspected under magnification for alignment, cover tape continuity and thickness, and a length of 200 to 500 mm is pulled through a spare feeder or a test fixture to confirm that indexing and peeling work.
Running the joint through before the reel is loaded is what turns the specification into evidence. It takes a minute, and it catches the tape lifted at one edge or the splice that has bonded to the adjacent pocket, both of which look acceptable on a bench. The pull test also shows whether the joint indexes cleanly, which a visual check cannot.
What a Bad Splice Produces
A mis-pitched joint produces a wrong or missing component, because the feeder indexes to a position where no pocket is present. A joint that is too thick produces a pick height error, which appears as a component placed at an angle or not at all.
A cover tape that peels unevenly leaves components standing in the pocket, which the vacuum nozzle may pick at an angle. All three signatures point at the same reel, and all three are avoided by the same checks. The faster a defect is traced to a reel, the smaller the quantity that has to be reworked.
Records and Operator Practice
Splices should be recorded against the reel and the machine, with the tape lot and the operator, so that a defect can be traced. Where a shop finds that splices are a recurring source of missing parts, the record is what shows whether the cause is tooling or technique.
Training matters more than documentation here, because the check is a judgement made by hand. A shop that keeps a splicing block at every line, replaces it when worn and expects the joint to be tested before loading will not see splice defects in its defect Pareto. Where they do appear, the record usually shows that the block was worn or the tape was old.
FAQ
Where should a splice be made? In the empty tape 200 to 400 mm before the end of the reel, never across a pocket. The joint then sits in a section the feeder passes without picking.
How thick can the joint be? Within about 0.1 mm of the carrier tape. A thicker joint lifts the tape in the track and changes the pickup height, which is a common cause of placement errors.
Is a splice check really necessary? Yes. Inspection under magnification plus a 200 to 500 mm pull through a feeder takes about a minute and removes the two failure modes that are hardest to trace, a missing component and a doubled one.
