Interface Standard 1.2

Interface Standard 1.
SMEMA
Surface Mount Equtpment Manufacturers Association
SMEMA Mechanical Equipment Interface Standard

Introduction
The SMEMA machine interface standards were developed to facilitate the interface of equipment used in the
manufacture of surface-mounted printed circuit boards. This standard is for Mechanical interfaces.
Purpose
The purpose of this standard is to provide an equipment interface specification for single board transfer
manufacturing systems of surface-mounted printed circuit boards. This specification provides the minimum
requirement that conveyor-to-conveyor equipment must meet, and does not represent a complete specification for
the equipment's interface. Conformance to the standard may be achieved by the appropriate design of the
equipment or by providing special adaptors which enable the equipment to meet the standard.
Specifications
The mechanical specifications that follow are for single board transfer systems with conveyor transports. These
systems can be assembled next to each other without any interface hardware. The printed circuit board is assumed
to move from left to right in the diaVr2n, E that follow; however, the same standard applies for systems when the
board moves from right to left. An equipment manufacturer must clearly state the direction of board movement.
1.) Conveyor height Each machine must have the transport conveyor height adjustable from 37" to
38" from the floor to the bottom of the PC board.
2.) Conveyor width For equipment with an adjustable conveyor width, the front rail is fixed and the
rear rail is adjustable. The range of adjustment will vary with the equipment
manufacturer.
3.) Edge clearance The conveyor should require no more than 0. 187" of clear board space at the
side edges.
4.) Tooling pins Tooling pins should be on the front edge of the board (next to the fixed transport
rail). A recommended hole diameter is 0.156"
(+.003, -.000). Distance from the edge is 0.300" + .010".
5.) Maximum gap The maximum gap between the in-line machine track ends is .375".
6.) Lead-in The minimum lead-in on the track ends of the conveyor is .1 25".
1
Interface Standard 1.2
SMEMA Electrical Equipment Interface Standard

Introduction
The SMEN4A machine interface standards were developed to facilitate the interface of
equipment used in the manufacture of surface-mounted printed circuit boards. This standard is
for Electrical interfaces.
Purpose
The purpose of this standard is to provide an equipment specification for single board transfer
manufacturing systems of surface-mounted printed circuit boards. This specification provides
the minimum requirement that the equipment must meet, and does not represent a complete
specification for the equipment's interface. Conformance to the standard may be achieved by
the appropriate design of the equipment or by providing special adaptors which enable the
equipment to meet the standard.
Figure 1. Electrical Interface Schematic
2
Specifications
A machine-to-machine electrical interface is required to insure proper sequencing of PC boards.
The interface is used for "Local" control and must operate independently of the cell controller.
1.) Electrical connections Each machine should be provided with a

separate power connection and ground.
Individual ON/OFF controls should also be
provided.
2.) Grounding Each machine should have 1/4-20 earth

ground stud on each side (left and right) of
the machine.
3.) Inter-machine control To sequence boards properly from machine-

to-machine, one or two signal lines will be
used: "Board Not Available" and "Board
Available."
3
These signals are shown in Figure 2, and may be obtained using an optical isolator or a relay.
The minimum requirements are to switch 3OV, 10 mA. At 10 mA, the output "LOW" must not
exceed 0.8 volts. The logic is as follows:
• Board transfer occurs when Machine A has a board available (contact closed), and
Machine B is not busy (contact closed).
• The signals can occur at anytime, but board transfer does not occur until both contacts are
closed.
• The Board is Available signal from machine A will remain closed until the board has left
Machine A.
• The Ready signal will remain closed until the board has arrived at Machine B.
• Board transfer cannot occur again until each signal opens for at least 50 ms.
• Optional: Once both Machine A and Machine B signals are closed, and the board has
neither left A nor arrived at B, an error message will be generated.
Figure 2. Timing Diagram
4
SMEMA Connector Specifications
Figure 4 SMEMA #001: Machine Connector
Figure 4. SMEMA #002: Cable Connector
About SMEMA
The Surface Mount Equipment Manufacturers Association (SMEMA) is a non-profit

organization of companies manufacturing equipment or producing software for surface mount
board production. Its objectives are to: promote standards for the interface and operation of
equipment, provide users with the ability to select equipment with the assurance that the
equipment will interface easily, advance SMT and promote its use and investigate areas where
the association can act to the benefit of all member companies.

Interface Standard 1.2

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Interface Standard 1.

SMEMA Mechanical Equipment Interface Standard

(+.003, -.000). Distance from the edge is 0.300" + .010".

SMEMA Electrical Equipment Interface Standard

Figure 1. Electrical Interface Schematic

1.) Electrical connections Each machine should be provided with a

2.) Grounding Each machine should have 1/4-20 earth

3.) Inter-machine control To sequence boards properly from machine-

Figure 2. Timing Diagram

SMEMA Connector Specifications

Figure 4 SMEMA #001: Machine Connector

Figure 4. SMEMA #002: Cable Connector

The Surface Mount Equipment Manufacturers Association (SMEMA) is a non-profit

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