FPC / PCB Engineering Calculator

Stiffener / ZIF Thickness Calculator

Check assembled FPC stiffener thickness against a connector or ZIF target thickness.

How to use the Stiffener / ZIF Thickness Calculator

Stiffener thickness is critical for ZIF, board-to-board, gold finger and connector support areas. This calculator checks whether the assembled local thickness matches the connector requirement.

Assembled connector thickness

Formula: Assembled thickness = FPC thickness + stiffener thickness + bonding adhesive thickness

FPC thickness: local flexible circuit thickness before stiffener.
Stiffener thickness: PI, FR-4, SUS or other support material thickness.
Bonding adhesive: adhesive used to attach the stiffener.
Target thickness: connector or customer-specified thickness window.

Formula Basis

Formula basis: arithmetic local thickness stack-up for connector insertion areas.
Engineering note: connector drawing limits, adhesive compression and stiffener material tolerance should be checked for release.

Example

0.12 mm FPC + 0.15 mm stiffener + 0.03 mm adhesive gives 0.30 mm assembled thickness.

Inputs

Target connector thickness
FPC thickness
Stiffener thickness
Bonding adhesive
Allowed tolerance

Outputs

Assembled thickness
Delta from target
Required stiffener thickness
Pass / warning indication

Engineering Notes

Connector drawings often define a strict insertion thickness window.
Adhesive compression and stiffener tolerance should be included for production release.
Stiffener edge should be kept away from bend areas to avoid stress concentration.

Validation Checks

ZIF thickness match
Connector fit
Adhesive thickness
Stiffener setback

Related Manufacturing Process

Stack-up Design - Total thickness, dielectric spacing, symmetry, controlled impedance
Lamination - Lamination thickness, adhesive squeeze-out, registration, CTE mismatch

Related Calculators

Copper Thickness Converter (1 oz to um) - Convert copper weight and thickness, including 1 oz to um, for stack-up and plating reviews.
Stack-up Thickness & Feature Drawing Tool - Build stack-up thickness and draw coverlay openings, air gaps, through holes, buried vias and blind vias for engineering review.
Engineering Unit Converter - Convert common PCB and FPC engineering units, including 1 oz to um copper thickness.

FAQ

Should adhesive thickness be counted?

Yes. The local insertion thickness includes the FPC, stiffener and bonding adhesive after lamination or bonding.

Can this tool choose the stiffener material?

Not yet. It calculates thickness. Material selection should consider stiffness, heat, cost, electrical insulation and assembly needs.