Design Guidelines for Printed Circuit Boards by Tek-Tronics

The following guidelines are provided for the purpose of assisting Tek-Tronics' clients in the matching of our production capabilities to their specific manufacturing requirements. Although these guidelines represent the full range of normal production capabilities, design parameters as stated may be exceeded under controlled conditions when indicated by client specifications. Please note that all parameters stated can be achieved independently, but may not in some instances be possible in combination.

Guidelines for Manufacturing and Testing Specifications
In order to eliminate ambiguity in the specification of manufacturing parameters, Tek-Tronics advises the procurement of boards manufactured to the intent of an accepted international standard, i.e. (IPC-A-600, Rev. E). In doing so, clients may be certain that manufacturing and testing processes are performed to the requirements of these specifications. Any non-standard or additional specification must be stipulated on the purchase order.

Design Parameters to be Specified
LAMINATE:
State applicable specification within the following preferred parameters:

Minimum core thickness 0.005"

Copper foil

outer layers: maximum 3 oz.; minimum 1/2 oz.

inner layers: maximum 2 oz. for power and ground layers; maximum 1 oz. for signal layers; minimum 1/2 oz. for all layers

CONSTRUCTION:
Tek-Tronics will employ all standard construction procedures required to provide the best-balanced build unless otherwise specified.

LIMITING DIMENSIONS:
Maximum active board size is 20" x 22.5" (including customer test patterns, where applicable)

Maximum number of layers	18
Minimum drilled hole	0.010"
Minimum conductor width	0.004"
Minimum spacing	0.004"
Board aspect ratio	6:1

BOARD THICKNESS:
Limiting tolerances on thickness (maximums):

0.020"	±0.003"
0.031"	±0.003"
0.062"	±0.007"
0.093"	±0.008"
0.125"	±0.008"

BOW & TWIST:
Under normal manufacturing tolerances, the typical acceptable deviation from flatness is 0.0075-0.015in./in. This specification is subject to the uniform distribution of circuitry across each layer.

FINISHES:
State finishes required, as follows:

Selective solder coating (hot-air leveling)

Gold over nickel over copper

Immersion white tin

Other finishes available upon request.

HOLE SIZES:
In the interest of reducing overall per-unit cost to its customers, Tek-Tronics recommends that clients specify the fewest possible number of hole sizes per each board design.

TOLERANCE OF OUTSIDE DIMENSIONS:
±0.005" minimum

DATUM POINT:
A common datum point must be specified for drilled holes, profiled slots, and boundaries.

PROGRAMMING LAYER:
This layer must be clearly shown in the drawing and will preferably be the layer with the smallest lands.

HOLE TOLERANCE:
Minimum hole diameter tolerances are as follows:

Nominal Diameter of Plated Through Hole
After Plating	Tolerances
0.035" or less	±0.002"
0.036" to 0.093"	±0.003"
above 0.094"	±0.005"

ANNULAR RING:
Minimum annular rings of lands on artwork should be 0.01" from finished hole size. Plated through holes require lands on both sides of the board to ensure continuity of circuitry. Through plating of the hole can be guaranteed only when this requirement is reflected in the design of the printed circuit board.

NON-FUNCTIONAL LANDS:
The inclusion of non-functional lands on inner layers is not recommended.

ISOLATION CLEARANCES:
Isolation clearances on artwork must be a minimum of 0.012" from the drilled hole, i.e. the epoxy-glass areas around holes in the ground/power plane.

ARTWORK DESIGNED ON GRID:
Artwork designed on grid should be indicated as such, as drilling to grid location is preferred.

SOLDER MASK & LEGEND:
If required, colors for solder mask and legend must be stated. Preferred colors:

Solder Mask: Green-Blue-Red-Black-Clear

Legend: White-Yellow-Black

CIRCUITRY:
Circuitry should be distributed uniformly across each layer to minimize variations in plated thickness and flatness on the finished board. In areas where low pattern density or ground planes are present, cross-hatching is often advisable.

CONDUCTOR WIDTHS:
Finished conductor widths must be stated. Tolerances depend on copper thickness.

ARTWORK:
The artwork nominal must be 0.002" greater than the nominal finished board requirement.

DESIGN NOTES:

Assistance with design tolerances, complexity issues, and board capabilities is available upon request.

Critical tolerances should be specified where acceptable.

Most tolerances are limited by the dimensional stability of the available base materials.