DESCRIPTION

Sheet adhesive in the DuPont™ Pyralux® product line is a proprietary B-staged modified acrylic adhesive coated on release paper. Sheet adhesive is used primarily to bond flexible innerlayers or rigid cap layers in multilayer lamination. It is also widely used to bond flexible circuits to rigid boards during the fabrication of rigid-flex circuits, as well as to bond stiffeners and heat sinks.


CONSTRUCTION

Sheet adhesive is available in a variety of thicknesses; see Table

1. The product code must be used when ordering sheet adhesive from DuPont.


Table 1 - Sheet Adhesive Product Codes

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Product Code*                                     Adhesive Mil (µm)              IPC Certification*

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LF0100                                                 1 (25)                                       Yes

LF0200                                                2 (51)                                        Yes

LF0300                                                3 (76)                                       Yes

LF0400                                                4 (102)                                     Yes

LF1500                                                  1/2 (13)                                   Yes

LF1700                                                   .7 (18)                                     Yes

LF1800                                                   .8 (20)                                    Yes

LF7049                                                   1.5 (38)                                   Yes

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*Certified to IPC-4203/18: “Adhesive Coated Dielectic Films for Use as Cover Sheets for Flexible Printed Circuitry and Flexible Adhesive Bonding Films.”

PACKAGING

Sheet adhesive is supplied on 24-inch (610 mm) wide by 250 feet (76 m) long rolls, on nominal 3-inch (76 mm) cores. Narrower widths or cut sheets are also available by special order.


TYPICAL DATA

Each manufactured lot of sheet adhesive is certified to IPC specifications and tested according to IPC Test Method TM-650. See Table 2.


Table 2 - Sheet Adhesive Properties vs IPC Specifications

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Adhesive Property                                                                                         IPC Spec                                     Typical Sheet Value

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Peel Strength*, min., lb/in (kg/cm) As received After solder              8 (1.4) 7 (1.3)                              10 (1.8) 9 (1.6)

Solder Resistance 10 sec at 288°C (550°F)                                              Pass                                               Pass

Adhesive Flow, max. mil/mil adhesive (µm/µm)                                   5.0 (127)                                        2–4 (51–102)

Dielectric Constant, max. (at 1 MHz)                                                        4.0                                                  3.6–4.0

Dissipation Factor, max. (at 1 MHz)                                                          0.05                                               0.02–0.03

Dielectric Strength volts/mil (kV/mm)                                                     1,000 40                                       2,000–3,000 80–120

Insulation Resistance megohm                                                                   10^4                                              10^5

Volume Resistivity, min., megohm-cm (ambient)                                  10^7                                              10^9

Surface Resistivity, min., megohm-cm (ambient)                                  10^6                                               10^8

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*Laminating Conditions: 14kg/cm2 (200 psi), 182°C (360°F), 1 hour to treated side of 1 oz RA copper foil. The values in Table 2 represent a typical 1 oz copper foil, 1 mil adhesive and 1 mil Kapton® construction.


A Certificate of Analysis is available with every batch. Complete material and manufacturing records for each lot, with samples of finished laminate, are retained for reference purpose. The roll labels contain the lot number, DuPont order number, customer order number, IPC specification, customer specification, and customer part number; save these labels for reference in case of inquiries.


PROCESSING

Laminating conditions for Pyralux® flexible composites are typically in the following ranges:

Part Temperature  : 182–199°C (360–390°F)

Pressure  : 14–28 kg/cm2 (200–400 psi)

Time  : 1–2 hours, at temperature
For further processing information contact your DuPont representative to receive a Pyralux® Technical Manual.


STORAGE CONDITIONS AND WARRANTY

DuPont™ Pyralux® LF Sheet Adhesives should be stored in the original packaging at temperatures of 4–29°C (40–85°F) and below 70% humidity. The product should not be frozen and should be kept dry, clean and well protected. Subject to compliance with the foregoing handling and storage recommendations, the DuPont warranty, as provided in the DuPont Standard Conditions of Sale, shall remain in effect for a period of two years following the date of shipment.


SAFE HANDLING

Pyralux® sheet adhesive contains a B-staged adhesive. Because B-staged adhesive contains trace quantities (parts per million) of unreacted monomers, precautions and recommendations should be taken to minimize contact.
DuPont is not aware of anyone developing contact dermatitis, or suff ering any other medical discomforts, when using Pyralux® products. The uncured acrylic monomers in the bond ply adhesive may impart a mild odor. However, these products have been extensively tested under operating conditions (drilling and lamination conditions) and found to liberate measurable volatiles only well below1 accepted safe limits (e.g., PEL).


To eliminate contact between the skin and the adhesive, wear lint-free gloves or fingerpads. Anyone handling Pyralux® should wash their hands with soap before eating, smoking, or using restroom facilities. Gloves and fingerpads should be changed daily, and wash other protective clothing frequently.
Adequate ventilation and exhaust is recommended in press rooms to prevent the buildup of potentially harmful vapors, to remove disagreeable odors, and to dissipate heat. Drill rooms should be furnished with standard equipment recommended by drill vendors and required by OSHA standards.
For further information on safe handling, refer to DuPont publication H-46862, “Pyralux® LF and FR Safe Handling;” and refer to “Industrial Ventilation,” 18th Edition or latest available from the American Conference of Governmental Industrial Hygienists, 6500 Glenway, Building D-5, Cincinnati, OH 45211.


1Values for all materials monitored were well below 10% of their accepted limits (PEL or TLV). In only one case, did the concentration reach approximately 40% of its limit. This was an oven used to dry the uncured acrylic material. This oven drying is not normally used in the process and during the exposure the oven was unventilated. Adequate ventilation is normally recommended for any heating process.