Build-up Dielectric Film for FC-BGA Substrates
NX04 Series (NX04H), NQ07 Series (NQ07XP)


SEKISUI Build-up Dielectric Films are used in high end IC package substrates with high build-up layers that require low insertion loss and warpage control.

Higher package design flexibly may be achieved by opting to use SEKISUI Build-up Dielectric Film as it can enable lower insertion loss and better reliability.

Build Up Film
Build Up Film

What is Build-up Dielectric (BU) Film

Build Up Film

Build-up Dielectric Film is the interlayer dielectric material that forms the interconnect in organic IC package substrates.

Benefits & Track Record

SEKISUI’s Build-up Dielectric Films are the ONLY alternative mass producing dielectric build-up material used in manufacturing of FC-BGA substrates with full compatibility with current Semi-Additive Process (SAP) manufacturing lines.

Several major substrate suppliers in Japan and Taiwan are manufacturing advanced FC-BGA substrates incorporating SEKISUI’s Build-up Dielectric Films and major OSATs have experience assembling those substrates.

Semi-Additive Process (SAP)

Semi-Additive Process (SAP)

Please contact us if you need detailed SAP manufacturing conditions when using SEKISUI Build-up Dielectric Film

Current Product Lineup

Next Target
(Under Development)
CTE (25-150°C) [ppm/°C] 24.5 27 24
CTE (150-240°C) [ppm/°C] 70 94 82
Dk (5.8GHz) 3.3 3.3 3.3
Df (5.8GHz) 0.0090 0.0037 0.0023
Tensile Strength [MPa] 100 105 110
Young’s Modulus [GPa] 8 10 12
Tg (DMA) [°C] 205 183 183
Elongation [%] 2.4 2.6 2.6
Ra (WYKO) [nm] 50 50 50
Available Thicknesses [μm] > 20 > 20 > 20
Flame Retardant (UL94) V0 V0 ( V0 ※yet to be certified)
Applications Package Substrates for CPU, Networking, PCIe Switch devices and more


Combination of SEKISUI’s chemical formulation technology and film coating technology enabled SEKISUI’s Build-up Dielectric Films to achieve low dielectric loss tangent (Df), maintain uniform low surface roughness with adequate adhesion after desmear process, and higher elongation to achieve high fracture toughness, resulting in customers possible to manufacture next generation substrates that have low insertion loss, finer line-and-space, improved reliability while maintaining high and stable substrate manufacturing yields.

Furthermore, SEKISUI’s unique position as a premier film and tape manufacturing company means build-up dielectric films of varying thicknesses can be accommodated and manufactured.


Detailed Technical Information

Technical information
Melt Viscosity (NX04H)
Melt Viscosity (NQ07XP)
FLS HAST Reliability (NX04H/NQ07XP)
LtL HAST Reliability (NX04H/NQ07XP)
Insertion Loss (NX04H/NQ07XP)
Examples of SEKISUI Build-up Film Customers
(FC-BGA Manufacturers)


SEKISUI is continuously working with IC design houses, semiconductor manufacturers, and substrate suppliers to develop new build-up dielectric films to enable next generation challenges facing advanced substrates such as lowering Df to meet the needs of 224Gb Ethernet Switch Products and beyond.
Please contact us for any development needs.