FPC Assembly Tape & Flexible Circuit Fixing Solutions
Application Summary
FPC assembly is not simply a matter of choosing a tape that can survive reflow. Flexible circuits are thin, soft, and easy to deform during SMT handling, carrier board mounting, component placement, reflow soldering, and tape removal.
In many production lines, the FPC is supported by a carrier board, jig, or fixture. Polyimide tape is then used as a temporary fixing material to hold selected edges, corners, or positioning areas in place.
The difficult part is balance.
If the tape holds too weakly, the FPC may shift, lift, curl, or deform during reflow. If the tape holds too strongly, it may leave adhesive residue, stress the coverlay, or damage the flexible circuit during removal.
The right FPC assembly tape should keep the flexible circuit stable through the process and remove cleanly afterward without creating new defects.
Common FPC Fixing Problems
FPC Shifting During SMT
Flexible circuits can move during handling, printing, component placement, or reflow if the fixing method is not stable enough. Even small movement can affect placement accuracy, solder joint quality, and inspection results.
Warping or Lifting During Reflow
The FPC may look stable before entering the reflow oven, but heat, airflow, thermal expansion, or insufficient fixing points can cause it to lift from the carrier board.
Adhesive Residue After Reflow
Residue is one of the most common complaints in FPC fixing. A tape may hold well before reflow but leave adhesive transfer after heat exposure. This increases cleaning work and may create inspection or downstream process concerns.
Peel Damage During Tape Removal
If adhesion is too aggressive, tape removal may stress the FPC coverlay, printed surface, edge area, or thin flexible section. Room-temperature tack is not enough. Peel behavior after reflow matters more.
Inconsistent Manual Fixing
Manual cutting and placement can vary between operators. For repeated FPC designs, this can lead to inconsistent holding force, uneven peel stress, and unstable process results.
Tape Structure Options
This section only covers tape structure. Performance requirements and converting options are discussed separately.
Single-Sided Polyimide Tape
Single-sided polyimide tape is usually the first option to test for FPC edge fixing, carrier board mounting, and temporary high-temperature holding during SMT.
It is typically applied to selected edges or corners to keep the FPC in position during handling and reflow. After soldering, it should remove without residue, tearing, or damage to the FPC surface.
Typical applications include:
- FPC edge fixing
- carrier board mounting
- SMT temporary holding
- reflow positioning support
- flexible circuit anti-shift fixing
For residue-sensitive FPC surfaces, clean-removal performance should be verified after the actual reflow profile, not only at room temperature.
Double-Sided Polyimide Tape for Selected Carrier Fixing
Double-sided polyimide tape may be tested in selected FPC carrier fixing or temporary positioning applications where single-sided edge fixing cannot provide enough contact area.
It should not be treated as the default solution. Because both sides have adhesive, double-sided polyimide tape may create higher removal force, higher residue risk, and higher peel-damage risk than single-sided edge fixing.
Typical checks include:
- peel force after reflow
- residue on FPC and carrier surface
- FPC coverlay stress
- removal angle and timing
- whether the FPC stretches, tears, or deforms during release
For many FPC fixing jobs, single-sided edge fixing is the safer starting point. Double-sided polyimide tape should be used only when the need for broader contact area is clear and removal behavior has been tested.
Key Performance Requirements
These are not separate product names. They are the performance requirements that should be checked when selecting tape for FPC assembly.
| Requirement | Why It Matters |
| Clean removal after reflow | Reduces cleaning, inspection, and rework |
| Controlled peel force | Too weak causes shifting; too strong may damage FPC |
| Residue control | Important for coverlay, copper areas, and downstream assembly |
| Heat stability | Needed during SMT reflow |
| Dimensional stability | Helps prevent tape shrinkage, curling, or movement |
| Suitable adhesion to FPC and carrier | Different surfaces may show different adhesion and release behavior |
| Low-static performance, if required | Useful only when ESD risk is part of the process |
| Non-silicone adhesive, if required | Relevant only when silicone contamination is restricted |
Low-static or non-silicone requirements should be treated as special process requirements, not as a separate tape structure category. A tape may be single-sided and low-static, or single-sided and non-silicone, depending on the construction available.
The key point: performance should be checked after the real reflow profile, not only at room temperature.
Custom Converting Options
Not every fixing problem is solved by changing the tape material. Sometimes the better answer is changing how the tape is supplied and applied.
Custom slitting, die-cutting, kiss-cut pieces, and removal tabs are converting options based on polyimide tape. They are not separate tape materials.
Custom Slitting
Standard polyimide tape can be slit to the required width for narrow FPC edge fixing, consistent application width, and reduced manual cutting.
Custom slitting is useful when operators need the same narrow tape width repeatedly and manual cutting creates variation.
Typical use cases include:
- narrow FPC edge fixing
- long straight fixing strips
- repeated tape widths
- high-volume production
- reducing manual cutting waste
Die-Cutting
Polyimide tape can be die-cut into shapes for repeated FPC designs, holes, slots, curves, or fixed positioning points.
Die-cutting is useful when manual cutting causes inconsistent placement, uneven edge coverage, or unnecessary handling time.
Typical use cases include:
- repeated FPC designs
- holes and slots
- curved or irregular areas
- fixed positioning points
- high-volume assembly
- areas where removal tabs are needed
Kiss-Cut Pieces and Removal Tabs
Kiss-cut pieces can make tape handling faster and easier. Removal tabs can reduce the risk of damaging the FPC during peeling, especially when the FPC is thin or sensitive.
These options do not change the basic tape material. They improve how the tape is applied, handled, and removed in production.
Selection Checklist
Before approving tape for FPC assembly, check these points:
FPC Surface
Confirm whether the tape contacts coverlay, copper, solder mask, stiffener, adhesive layer, or carrier board surface. Different surfaces may behave differently after reflow.
Carrier Board or Fixture Material
The tape may contact both the FPC and the carrier board. Carrier surface condition can affect adhesion and release.
Reflow Profile
Test the tape under the actual SMT reflow profile. Heat exposure can change peel force, residue behavior, and removal stability.
Holding Force
The tape must prevent shifting, lifting, or curling, but stronger adhesion is not always better. Controlled holding force matters more than maximum tack.
Removal Behavior
Check whether the tape removes cleanly after cooling. Watch for residue, coverlay stress, edge lifting, tearing, stretching, or FPC deformation.
Tape Width and Thickness
Tape width and thickness affect holding force, peel stress, handling, and removal risk. Narrower tape may reduce peel stress, but it still needs enough holding power.
Production Volume
For repeated FPC shapes or high-volume assembly, custom slitting or die-cutting may reduce labor and improve repeatability.
FPC fixing is more sensitive to peel force and tape thickness than general PCB masking. For custom slit rolls and application-based selection, visit our custom polyimide tape supplier page.
Typical Tape Construction
This table compares tape construction only. Performance requirements and converting options should be evaluated separately.
| Tape Structure | Backing | Adhesive | Better Fit | Main Risk to Check |
| Single-Sided Polyimide Tape | Polyimide film | Silicone PSA or process-specific PSA | FPC edge fixing, temporary holding, carrier board mounting | Balance holding force, residue, and peel damage |
| Double-Sided Polyimide Tape | Polyimide film | Silicone / acrylic PSA, depending on construction | Selected carrier fixing when single-sided edge fixing is not enough | Higher removal force, residue, or FPC damage risk |
Special requirements such as low-static performance or non-silicone adhesive should be discussed as process requirements, not as separate structure categories.
Actual performance should always be verified on the real FPC, real carrier board, and real SMT process.
Related Products and Capabilities
Single-Sided Polyimide Tape for FPC Assembly
High-temperature polyimide tape for temporary FPC fixing during SMT, carrier board mounting, and reflow soldering.
This is usually the first tape type to test for FPC edge fixing and temporary positioning.
Double-Sided Polyimide Tape for Selected Carrier Fixing
Used only in selected carrier fixing or temporary positioning applications where broader contact area is needed.
This option should be tested carefully for removal force, residue, and FPC damage after reflow.
Custom Slitting Service
Polyimide tape can be slit to custom widths for narrow FPC edge fixing, consistent application width, and reduced manual cutting.
Die-Cutting and Kiss-Cut Converting
Polyimide tape can be converted into pre-cut shapes for repeated FPC designs, holes, slots, curves, and fixed positioning areas.
Kiss-cut formats and removal tabs can make application and removal easier, especially where thin FPCs are sensitive to peel damage.
Special Process Requirements
If your process requires low-static performance, non-silicone adhesive, or stricter residue control, these requirements should be confirmed during sample selection and validated on the real FPC and reflow profile.
