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Printed Circuit Boards in non woven aramide for Space applications

Printca APS - Svendborgvej 3-5 - Aalborg - Denmark - +45 5076 200 - www.printca.dk

Mission statement

”Printca aims to be the preferred and market leading PWB partner to the defence-, space- and aerospace industry”

Supplemented by particularly demanding industrial customers


CTE mismatch, will reduce reliability

CTE mismatch will give risk of cracks in solder joints after thermal excursion


Why did Printca select the Thermount ®®

� Low CTE need by key OEM’s� Main applications; Eurofighter Typhoon and Gripen fighters� Seen possible to Space qualify

� Conventional fabrication methods with no risk of contamination of process areas with e.g. conductive fibers

� Availible with polyimide and high Tg epoxy resin systems� Supported by existing supply partner for polyimide

products (Arlon)� Good dielectric parameters like low dielectric constant

and low weight


Background – Thermount ®®

� Thermount is a non-woven aramid fabric produced by DuPont-Teijin Advanced Papers in Japan

� Thermount offers a unique combination of light-weight, high tensile strength material with low in-plane thermal expansion

� Primary uses include both commercial electronics as well as defense & aerospace electronics


Thermount ®® – supply chain

� DuPont-Toray is a joint venture between E.I. DuPont & Toray Industries� Manufactures aramid fiber/floc

materials in Japan

� DuPont-Teijin Advanced Papers is a joint venture between E.I. DuPont & Teijin� Manufactures Thermount fabric in

Japan

DuPont-Toray JVaramid fiber/floc

DuPont-Teijin JVThermount Fabric

ArlonLaminate & Prepreg

PCB Fabricators


Thermount ®® availibility

� Thermount has historically been available in several fabric styles differentiated by fiber type & fabric density� E-Series:

� Includes E210, E220 & E230 grades� Original U.S. Thermount style used in 85NT & 55NT� currently dominates material in defense/aerospace applications

� N-Series: N710 series � Includes 2N710, 3N710 & 4N710� 2nd generation U.S. Thermount, used in 85RT, 55RT, 55ST, 55LM & 65GT� Predominantly commercial applications

� N-Series: N740 series� Includes N740#40 & N740#80� Historically only available in Japan

� Printca has since year 1999 supported the E-series (epoxy and polyimide)


Density and permittivity


Thermount ®® is proven

Arlon 85NT Polyimide ThermountArlon 85NT Polyimide Thermount®®

Key Benefits of Polyimide ThermountKey Benefits of Polyimide Thermount®®

High Tg (250High Tg (250ooC) / Higher LayerC) / Higher Layer--CountCountLow Cost CTE vs. CIC, Woven KevlarLow Cost CTE vs. CIC, Woven KevlarManufacturabilityManufacturabilityPTH ReliabilityPTH Reliability

Applications for Arlon Polyimide ThermountApplications for Arlon Polyimide Thermount®®

Include: Commercial and Military Avionics (Boeing 777)Include: Commercial and Military Avionics (Boeing 777)75% of the Avionics on the Eurofighter75% of the Avionics on the EurofighterDSMAC Digitally Mapped Guidance SystemDSMAC Digitally Mapped Guidance Systemfor the Tomahawk Cruise Missilefor the Tomahawk Cruise MissileESA approved for sequential MLB since ESA approved for sequential MLB since year 2000year 2000

THERMOUNTTHERMOUNT®® AND THERMOUNT RTAND THERMOUNT RT™™ ARE TRADENAMES OF THE DUPONT ARE TRADENAMES OF THE DUPONT COMPANY, WILMINGTON, DECOMPANY, WILMINGTON, DE

Thermount®® rigid/flex

Thermount®® with resin filled blind viaswith resin filled blind vias


Limited resin filling properties

� Due to low resin content prepreg, filling properties are limited

� For 70µm innerlayer copper, a glass/polyimide prepreg sheet is needed

� Blind via fill in sequential boards, also needs glass/polyimide prepreg (or other filling material)


Low in-plane x-y CTE


Thermount ®® 85NT, Material Avalibility

� Prepreg types (all on stock at Printca)� 210, 46 µm� 220, 76µm� 230, 94 µm

� Most common laminate types on Printca stock� 4 mil 35/35� 5 mil 35/35� 8 mil 35/35� 14 mil 35/35


Low dielectric constant

Dieletric constant depends on frequency and moisture level in dielectric

3

3.5

4

4.5

5

5.5

1 10 100 1000 104

Frequency - MHz

Glass/FR4 - 85/85 Saturated

Glass/FR4 - Bone-dry

THERMOUNT - 85/85 Saturated

THERMOUNT - Bone Dry


Moisture absorbtion

� Like other polyimide dielectrics, moisture removal before assembly is nessesary


E-series fabric not in production anymore

� From January 2007 Dupont stopped the E-series fabric (reinforcement) production

� Last buy options were availible� 160.000 Sq. foot reservation made by Printca� With current programs the need for fabric is expected

covered until end of 2011� New low CTE product to replace the Thermount E-series

is under development by Arlon� 85XT is under trial production and evaluation in the PCB

industry


Board Build-up rules

� Use symmetric build� Limit copper thickness to 35microns (low resin content and

poor resin flow) � Limit copper plane amount to reduce CTE� Blind vias are possible with filling prepreg (glass/polyimide

style)� Printca PID approval cover up to max. 16 layers� Be aware of very smooth surface (low peel strength)� Assembly process, has to be controlled concerning

moisture level in boards (like all other bare boards)


Printca results with new 85XT

� Build of sequential, thick and high layer count boards� Use of existing proces flow and parameters to compare

similarity with E-series Thermount� Dimensional stability same as today� Drilling and plating results close to same results as seen

today� Some small spot discoloration seen � Next step is further cooperation with Arlon concerning

results and future release

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