PRINTED WIRING BOARD
FLEXIBLE LAMINATE
flexible laminate
FLEXIBLE LAMINATE

The thin films used in flexible circuitry offer significant width and space savings over traditional rigid designs and allow the development of printed boards that can be bent and folded in three-dimensional (3-D) configurations. Flexible boards may be single, double or multi-layer; may contain through-hole, surface mount or mixed technology; and, can be constructed wholly of flex or a combination of both flex and rigid (see rigid-flex, section 5.04).

See Section 5.01 "Printed Wiring Board, General Requirements", for common accept/reject criteria.

flexible laminate coverfilm

PREFERRED

GENERAL

Flexible circuit is clean, smooth, of uniform thickness and free of damage. Solderable surfaces are clean and bright. Markings are legible and properly oriented.

PREFERRED

COVERFILM

The coverfilm is smooth, clean and of uniform thickness. There is no evidence of bubbles, creases, delamination, entrapped particles, gouges, tears or ripples. Alignment and registration are correct.

Best Workmanship Practice

trimmed edge of laminate coverfilm registration

PREFERRED

TRIMMED EDGE

The trimmed edge shall be free of burrs, nicks, delamination or tears. Minimum edge to conductor spacing shall be maintained.

Best Workmanship Practice

ACCEPTABLE

COVERFILM REGISTRATION

The coverfilm is aligned and registered within engineering specification. All annular ring cutouts are centered, and there is no evidence of unwanted material on land areas.

Best Workmanship Practice

NASA WORKMANSHIP STANDARDS
NASA logo Released:
04.05.2002
Revision:
Revision Date:
Book:
5
Section:
5.03
Page:
1




PRINTED WIRING BOARD
FLEXIBLE LAMINATE (cont.)
edge nicks on laminate plated surfaces

ACCEPTABLE

EDGE NICKS

Nicks along the edges of the flexible printed wiring, cutouts and unsupported holes are acceptable, provided minimum edge to conductor spacing is maintained and damage is within agreed-upon limits.

Best Workmanship Practice

ACCEPTABLE

PLATED SURFACES

Plating is uniform, smooth and shiny. Holes are smooth and clean. No evidence of solder wicking/plating migration.

Best Workmanship Practice

surface scuffing tie in tab tears

ACCEPTABLE

SURFACE ROUGHNESS/SCUFFING

Minor roughness or scuffing of the laminate surface is acceptable, provided the damage does not reduce reliability or interfere with the design of service/operability.

Best Workmanship Practice

ACCEPTABLE

TIE-IN TAB TEARS

Minor nicks and tears that result from the use of tie-in tab design are acceptable, provided the damage does not reduce edge to conductor spacing below minimum requirements, or exceed the damage requirement agreement.

Best Workmanship Practice

creases in laminate edge nicks in laminate

UNACCEPTABLE

CREASES

Creases reduce the current carrying capability and reliability of the printed conductors and the bond integrity of the laminate. Flexible circuits shall exhibit proper bend radius and strain relief.

Best Workmanship Practice

UNACCEPTABLE

EDGE NICKS

Nicks along the edges of the flexible printed wiring, cutouts and unsupported holes which reduce minimum edge to conductor spacing below minimum requirements or expose conductive surfaces, are unacceptable.

Best Workmanship Practice

NASA WORKMANSHIP STANDARDS
NASA logo Released:
04.05.2002
Revision:
Revision Date:
Book:
5
Section:
5.03
Page:
2




PRINTED WIRING BOARD
FLEXIBLE LAMINATE (cont.)
foreign material in covercoat physical damage to laminate

UNACCEPTABLE

FOREIGN MATERIAL IN COVERCOAT

Foreign material under the covercoat represents a contamination and reliability concern.

Best Workmanship Practice

UNACCEPTABLE

PHYSICAL DAMAGE

Cuts, nicks, gouges, tears or other physical damage that result in exposed circuitry or reduce electrical separation below minimum requirements are unacceptable.

Best Workmanship Practice



















NASA WORKMANSHIP STANDARDS
NASA logo Released:
04.05.2002
Revision:
Revision Date:
Book:
5
Section:
5.03
Page:
3





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