What are the advantages of flex PCBs?

Flexible PCBs are lightweight, easy to install, durable, and compact. The wide range of motion makes it ideal for nearly all applications. Use flexible circuits in “bend to install” applications or dynamic applications, where the circuits are continuously in motion. Flexible circuits are also advantageous for the design packages where space is a primary concern.

We offer three types of flex PCBs:

• Flex
• Rigid-flex
• HDI flex

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Physical advantages for flex:

More flexibility, as the name suggests
Improved resistance to vibrations and movement; lower mass/weight
Small package size
Allows the board to bend to its desired applicable shape
Allows for more compact devices
High tensile strength—can be significantly warped/deformed without breakage
High bendiness—up to 360 degrees
Easier to prepare for harsh environments
The use of flexible flat cables (FCC), which can bend without being damaged, and takes up less space than traditional wires

Manufacturing & assembly advantages:

Increase in design freedom
Installation flexibility
Increased reliability and durability
Improved heat dissipation
Improved airflow

Flex Capabilities (Advanced)

PCB Attributes

Product FeaturesFlexRigid-Flex
Min Layer Count11
Max Layer Count12≥ 16
Min Core thickness.001″.002″
Max Finished Copper Weight (I/L)2 oz3 oz
Max Finished Copper thickness (O/L)12 micron9 micron (only for O/L)
Max Panel Size12×1812×18
Smallest Mechanical Drill Diameter.0079″.0071″
Smallest Laser Drill DiameterNo.005″
Min Finished Hole Size.006″.006″
Max through Hole Aspect Ratio10:110:1
Max Blind Via Aspect Ratio.75:1.75:1
Min Trace and Space≤ .0035″≤ .0030″ (rigid)
Min Pad Size for Test.016″.005” (rigid)
Process Pad DiameterD + .014″ (1-mil Annular Ring)D + .014″ (1-mil Annular Ring)
Stacked ViasNoNo
Min Wire Bond Pad Size> .006″> .006″
Controlled Impedance Tolerance10%5%
Solder Mask RegistrationWithin .002″Within .002″
Solder Mask Feature Tolerance.001″.001″
Solder Mask Min Dam Size.004″.001″
Min Diameter Route Cutter Available.019″.024″
Mechanical Routed Part Size Tolerance.003″.010″
Bow and Twist ToleranceN/AAs per spec
Thickness Tolerance+/- 0.00210%
Sequential Laminationsn/a2
Buried ViasYesYes
Blind ViasYesYes
Conductive Filled ViasNoYes
Non Conductive Filled ViasNoYes

Surface Finishes

Product FeaturesFlexRigid-Flex
HASL (Vertical or Horizontal)Yes (not recommended)Yes
Lead Free HASL Yes (not recommended) Yes
OSP (Shikoku F2) Yes (not recommended) Yes
OSP (Entek) Yes (not recommended) Yes
ENIG (Electroless Nickel/Immersion Gold)Yes (most common)Yes
Immersion Silver Yes (not recommended) Yes
Immersion White TinNoNo
Tin NickelNoNo
Electrolytic Soft GoldYesYes
Electrolytic Hard GoldYesYes
Selective GoldYesYes

Solder Mask Colors

Product FeaturesFlexRigid-Flex
Bright WhiteNoYes


Product FeaturesFlexRigid-Flex


Product FeaturesFlexRigid-Flex
Routed ArrayYesYes
V Score, Edge to Copper.002″.01″
V Score AnglesNoYes
Edge CastellationYesYes
Edge PlatingYesYes

Electrical Test

Product FeaturesFlexRigid-Flex
10 VoltYesYes
40 Volt (Burn-In Boards)YesYes
250 VoltYesYes
500 VoltYesYes

Laminate Materials

Product FeaturesFlexRigid-Flex
Flexible PoyimideYesYes
Arlon 85NTNoNo
Hybrid ConstructionsYesYes
Isola FR406 Yes Yes
Isola FR408 HR Yes Yes
Isola P95 Yes Yes
Isola P96 Yes Yes
Iteq IT180 Yes Yes
Panasonic R1766 Yes Yes
Panasonic R1755 Yes Yes
Panasonic Megtron Yes Yes
Nelco N4000-13 Yes Yes
Nelco N4000-29 Yes Yes
Nelco BT N5000 Yes Yes
Nelco N7000-2 Yes Yes
No Flow Prepreg Yes Yes
Isola 370HR Yes Yes
Polyclad GetekNoNo
PSA Bond FilmYesYes
Rogers 3000 SeriesNoNo
Rogers R4000 SeriesNoNo
Rogers 5000 SeriesNoNo
Rogers 6000 SeriesNoNo
Rogers TMMNoNo

Available Reports

Product FeaturesFlexRigid-Flex
X-Ray FluorescenceYesYes
Ionic ContaminationYesYes
Time Domain Reflectometry Test (TDR)YesYes
Certificate of ComplianceYesYes


Product FeaturesFlexRigid-Flex

PCB Classifications Mil-Spec

Product FeaturesFlexRigid-Flex
IPC 6012, Class 1, 2 and 3YesYes
ISO 9001:2015YesYes
ISO 13485:2016YesYes

Note: Sierra can handle more advanced parameters depending on design.