CUSTOMER APPLICATION: Product
Quality Control Test Line
During manufacture of PC motherboards,
reflow soldering is used to secure
components in place on printed circuit
boards. Following assembly, boards are
conveyed into a reflow oven, where the
temperature increases progressively to
achieve a predetermined thermal profile,
melting the solder paste on the boards.
As each board leaves the oven, a
sensor must trigger the customer’s
control system and activate a transfer
mechanism, moving the board
automatically to the next process stage.
The ambient temperature immediately
adjacent to the oven may reach 80°C
(176°F), which has caused unacceptable
rates of failure of other manufacturers
sensor in the past, whereas sensors must
operate continuously in this environment
with ultra-high reliability to achieve the
required OEE and throughput.
Extended sensing distances are highly
desirable for this application as several
types of motherboard, each with
different component heights, pass
through the oven. The longer-distance
sensing enables the sensor to be
positioned further away from the hot
boards.
CUSTOMER SOLUTION:
Contrinex inductive sensors from the
Extra Distance family (500 series) are
ideal for this application, with their
vacuum-encapsulated electronics
ensuring excellent resistance to
thermal shock and vibration. Condist®
technology delivers best-in-class
operating distances and sensors
have a continuous rating to 70°C
(158°F). Trials confirmed highly stable
performance even in the elevated
ambient temperatures around the reflow
oven, without the need to use high-
temperature sensors.
Extra Distance sensors are mounted
vertically on steel brackets attached
to the exterior of the reflow ovens and
sense the presence of each motherboard
as it passes beneath the sensing face.
The operating distance is set at 10mm,
eliminating the risk of collision with
components on the board, and an M12-
threaded metal housing allows easy
positional adjustment when necessary.
Extra Distance sensors with an
industry-standard NPN normally-
open configuration connect with the
customer’s control system via a flexible
PVC sheathed cable. No additional
electrical or mechanical protection
is required in spite of the adverse
operating conditions.
Previously, sensors from other
manufacturers did not detect boards
reliably and had unacceptably short
service lives, causing frequent
interruptions to production. Sensor
replacement costs were excessive.
Contrinex inductive sensors have been
reliable and long-lived, providing a
professional sensing solution with an
attractive total cost of ownership.
To find out more, or to discuss how I can
help reduce price and cost on
sensors please email me
[email protected]
www.contrinex.com
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