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Glossary of PCB Assembly Terms
A | B | C | D | E | F | H | I | L | M | N | P | Q | R | S | T | U | W | Z
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A
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Accumulating
Conveyor |
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Stores
a number of boards from the upstream line and releases them
one at a time into the downstream line. The standard length
is normally 72 inches and is used ahead of any operation in
a line that has a variable cycle time. One example would be
on the output of a re-flow oven, allowing the oven to be ahead
of some manual assembly or test operation. The Accumulating
conveyor utilizes a special low friction, continually running,
edge carry chain that allows the boards to "accumulate" against
a stop at the end that then releases them one at a time when
the next operation calls for a board. |
AOI |
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Automatic Optical Inspection.
Uses television and computer technology to look at and make
an inspection of a PCB or other object. |
Assist |
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A condition
that causes the machine to stop, requiring operator intervention
to resume operation. |
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B
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Bare
Board Loader |
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Takes bare unpopulated
PCBs from a stack and feeds them one at a time to the production
line. Dyna3 offers BBLs that hold an 18-inch or a 6-inch
stack of boards. |
Board Inverter |
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Used to turn a board over
when processing 2-sided boards. Example after side one is
complete, turn over before the screen printer for the second
side. Edge Carry only. |
Buffer Storage |
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An edge carry
conveyor that accepts boards from the upstream line and either
passes them through or stores them within the machine for
future processing. Depending on the requirements of your process
FIFO or LIFO are available. An example would be on the output
of an oven to allow it to empty in the event of a downstream
stoppage. Buffers are also available with removable storage
units called “magazines” for off line storage or moving. See
Magazine Storage. |
Board Cleaner |
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A machine used in the production
line to remove solder residue and other foreign material acquired
during assembly from the PCB. These cleaners can be Inline
or batch type, the latter requiring the boards to be loaded
into the machine prior to washing similar to the kitchen dishwasher. |
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C
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Case Controlled |
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Continuous
run conveyor without PLC control. |
Communication |
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The product transfer electrical
interface “handshaking” that occurs between two adjacent machines.
The standard used is SMEMA 1.2 |
Control Functions |
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E-Stop: Push
for Emergency Stop, twist & pull out to reset.
Start/Reset: Push to start, If in E-Stop press to reset.
Release: In Audit mode releases stopped PCB.
Audit/Bypass: Select Audit/Bypass Audit-Stops PCB waiting
for operator to press.
Release; Bypass-passes product through. |
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D
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Disconnect |
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Mechanically engaged switch
located on the electrical enclosure door and wired into the
machine power circuit designed to remove AC supply power when
the door is opened. |
Downstream |
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Any location
after the present or reference machine position within the
in-line configuration of assembly machines. |
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E
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Edge Carry Conveyor
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Uses a narrow
belt or chain that contacts just the edge of the PCB, not
interfering with components or leads on the bottom side of
the board. |
Edge Contact
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Width of the belt contact
along the edge of a board in an Edge Carry Conveyor. Dyna3
normal maximum is 0.187 inches although narrower edge clearances
are available. May also be called Edge Clearance. |
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F
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Fault |
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An operational
or component failure condition that causes the machine to
stop immediately requiring attention to resume operation. |
Flat Belt
Conveyor |
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Utilizes a wide flat belt to carry
the product. Dyna3 Flat Belt Conveyors are available up
to 24-inch widths. |
Follow the
Leader |
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See: Width Adjustment
Types |
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H
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Hand Crank
Width Adjust |
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See: Width Adjustment
Types |
Heavy Duty
Conveyors |
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Dyna3 offers
a line of Heavy Duty Edges long, 24 inches wide and weighting
up to 75 lbs Carry Conveyor products that are capably of handling
boards up to 42 inches |
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I
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Incline/Decline Conveyor |
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Used as an interface between
the exit height of a specific wave solder machine and a specific
downstream line height. Normally Flat Belt but Edge Carry
available. Cooling fan hoods are also an option. May also
be referred to as a Wave Exit conveyor. |
Interlock |
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Mechanically
engaged switch located on the hinged and removable machine
guards and wired into the machine E-STOP circuit. |
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L
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Light Curtain |
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The use of
multiple photocell and light sources arranged to form a “curtain”
of light beams, which will detect a person, or object that
pass through the curtain. When normally used in product detection
situations two or more photocells must “see” the object to
confirm its presence. This is done to prevent “false” recognition
if for some reason only one light beam is broken. Also used
as a safety shield around potentially hazardous machinery.
An array of sensors is used to create a “curtain” of light
and any light beam broken by a person will stop machine operation. |
Lift Gate |
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A conveyor that an operator
manually lifts, like a drawbridge, to allow a walkway in a
production line. Normally used for maintenance access. |
Line Height |
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Height of the
Line above the floor. The SMEMA standard is 37.5 inches +/-
0.5”. |
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M
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Magazine |
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A portable enclosure used
to hold PCBs or product. These allow manual movement from
one process to another. As an example: rejected product to
a rework station or movement of product between production
areas that are separated by a large distance. |
Magazine Loader |
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Accepts PCBs
for the upstream line and stores them in a removable enclosure
called a "magazine”. This is a convenient way to collect
defective boards for movement to a rework station.
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Magazine Unloader |
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Removes PCBs from the magazine
placing product into the production line. |
Multi-Magazine Loader/Unloader
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Loads and unloads
PCBs to and from magazines to the production line. Up to 5
magazines are buffered (2 empty, 2 full, and 1 in process). |
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N
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Next |
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The adjacent machine that receives
product transferred out from previous (feeding) machine. |
NFPA |
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National Fire
Protection Association (http://www.nfpa.org/)
Sets electrical and fire safety standards for industry. |
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P
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Pallet / Carrier |
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A frame used to hold a PCB
during assembly. These are used primarily for manual assembly
on a “slide line” or to hold smaller or odd shaped boards
as they pass through a wave solder machine. In many applications,
PCBs are irregular in shape and size, large and heavy, or
have special components or devices that require masking. In
such cases the pallet carrier is an ideal solution to an otherwise
difficult situation. Dyna3 fabricates a wide variety of
circuit board carriers to meet any application. |
PCB or
Printed Circuit Board |
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The “Printed
Circuit Board” replaced point-to-point wiring beginning in
the 1960s. The PC boards start out with a thin solid copper
sheet bonded to a fiberglass board. The circuits are not “printed”
on the board but rather those areas of the copper not required
to create the circuit are etched away by a photographic process.
This leaves only the interconnections that you see on the
Printed Circuit Board creating wiring for the circuit. |
Pick & Place Machine |
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Automatically “picks” components
from a supply, normally a roll, or bin and “places” them on
the PCB in their appointed spot. Depending on the technology
used in certain model machines these may referred to as “Chip
Shooters.” |
PLC |
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Programmable
Logic Controller. (Simple Computer) |
Power Width Adjust |
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See “Width Adjustment
Types” |
Previous |
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The adjacent
machine that transfers product into next machine. |
Progressive Assembly |
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Manual assembly line with
workstations spaced along the line where each worker adds
components to the PCB. Unlike a “manual slide line”, built
in conveyors move boards along the line. |
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Q
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Quick Width
Adjust |
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See: Width Adjustment
Types |
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R
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Reflow Oven |
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PCBs are carried
through the Oven on edge carry chains or a moving wire mesh
belt while the temperature is raised to very specific settings
to melt the paste screened on the board there by soldering
the components. |
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S
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Selective Solder Machine |
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Solders only areas on the
PCBs programmed in to the machine. Uses a small fountain of
Solder. Sometimes used for components that were manually placed
or added after the reflow process. |
Screen Printer |
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Uses a silkscreen
like process to put flux & solder in the form of a “paste”
on PCBs where the component leads mount. |
Shuttle Gate |
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An Edge Carry conveyor that
automatically extends and retracts to deliver boards across
a normally open walkway in the production line. There are
two types. “Extend to deliver” or “extend to receive”. |
Shuttle Transfer Table |
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Used to distribute
product between two parallel processes using a horizontal
moving table. For example two can be used to allow two production
lines to share a single reflow oven. |
Slide Line |
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An assembly line where PCBs
are moved along manually by the workers from station to station
as parts are inserted in the board. These look like long workstations
with workers spaced every 3 or 4 feet along the line, sometimes
working from both sides of the line. Slide lines are available
with the rails flat or tilted at an angle. |
SMEMA |
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Surface Mount
Equipment Manufacturers Association sets standards used within
the SMT industry. Dyna3 most often refers to the SMEMA
Mechanical Equipment Interface Standard 1.2 Electrical Interface.
Communication protocol between machines for example. Complete
information on this standard is available at the IPC Association
Connecting Electronics Industries website (www.ipc.org). |
SMT or Surface Mount
Technology |
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The component leads only
touch pads on the “surface” of the PCB. They are held in place
by the stickiness of the paste, which contains solder and
flux, until they pass through the Reflow oven, which actually
melts the paste soldering them in place. This enhances full
automation of the assembly process as well as making better
use of the space on the board. |
SMTA |
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Surface Mount
Technology Association (http://www.smta.org/) |
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T
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Through Hole Process |
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Component leads are placed
in holes in the PCB at points where they are to be soldered.
The hole is then filled with solder to complete the process. |
Transfer |
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Movement of product
into, across, and then out from the machine conveyor. |
Transfer Conveyor |
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Incorporates
intelligent control like a PLC (Programmable Logic Controller)
or computer to control the movement of boards or product. |
Transfer Workstation |
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An Edge Carry
or Flat Belt conveyor that incorporates a work surface, light
and shelf for easy human interface with product as it passes
on the line. |
Turntable |
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Used to rotate boards where
changes in direction of the production line are encountered.
Normally 90 degrees but could be any angle. Also can be used
to divert defective product from the main line after an inspection
station or introduce reworked product into the line before
inspection. |
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U
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Upstream |
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Any location
before the present or reference machine position within the
in-line configuration of assembly machines. |
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W
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Warning |
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A condition that requires
attention before the operation of the machine is affected. |
Wave Exit Conveyor |
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Used as an interface
between the exit height of a specific wave solder machine
and a specific downstream line height. Normally Flat Belt
but Edge Carry available. Cooling fan hoods are also an option. |
Wave Solder Machine |
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Passes the PCBs over a “wave”or
weir of solder within the machine that just makes contact
with the bottom of the board soldering the components. Wave
Soldering is used mainly in the through hole manufacturing
process. As a rule the boards travel up an incline within
the machine making the output of wave solder machines higher
than the input. There is no standard exit height and may vary
from model to model so exit conveyors are custom made to match
a specific model solder machine. |
Width Adjustment Types |
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Quick Width
Adjust: Manually unlock handles and slide the adjustable rail
to desired width.
Hand Crank Width Adjust: Moves the adjustable rail by turning
a hand crank.
Power Width Adjust: Manually operated motorized width adjustment.
Push one button to send adjustable rail away from the fixed
rail a 2nd button to bring adjustable rail closer to the fixed
rail a digital width readout is available.
Follow the Leader: Linking many machines to progressively
move the adjustable rails to the width setting on a master
unit.
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Z
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Zone 2X, 3X etc. |
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This refers to how may “segments”
or zones a given conveyor unit has. Each zone is a separate
conveyor section placed end to end with others in a single
frame “rail” so that a PCB can be moved from zone to zone. |
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