IPC9850_Surface Mount Equipment Characterization.pdf - 第22页
IPC-9850 Official Proposal May 2001 22 Table 4-4 Terms Definition Feeder assist time: A machine stop required to recover/replace a damaged feeder or " un-jam" a feeder. Excludes parts replenishment. Measured fr…
IPC-9850
Official Proposal
May 2001
21
level of performance over 3 million placements. The same is also true for the mean placements between assists
(MPBA) parameter (see 4.2.1), were at least 3 times as many placements as is reported for MPBA need to be made.
Since several machines shall be utilized for the collection of data for the reliability metric on multiple machines, the
following method shall be utilized for merging the data sets. For example, assume a supplier has data for two
machines of a particular model type. The first machine was observed for 300,000 placements and experienced 2
assists while the second machine was observed for 500,000 placements and experienced 3 assists. The calculation
for MPBA for the model type would be the total number of cycles divided by the total number of assists. In this
case, MPBA would be
000,160
3
2
000,500000,300
=
+
+
cycles.
Other metrics shall also be calculated this way when multiple machines have been observed.
An assist is defined as an unplanned interruption that occurs during an equipment cycle where all three of the
following conditions apply:
Ø The interrupted equipment cycle is resumed through external intervention (e.g., by an operator or user, either
human or host computer).
Ø There is no replacement of a machine part (defined specifically to distinguish from component parts being
placed by the machine), other than vendor specified machine consumable parts.
Ø There is no further variation from specifications of equipment operations.
This definition was clarified not to include replenishment of components since it is tied to the type of feeders and
tape capacity choices made by the user. It was agreed that replenishment is to be specified as a scheduled downtime.
A failure is defined as any unplanned interruption or variance from the specifications of equipment operation other
than assists.
Preventive Maintenance (PM) is a machine stop required by the supplier's published PM schedule.
See table for 4-4, below, for examples of the terms ‘Assist’, ‘Failure’, and ‘Preventive Maintenance” as applicable to
this standard:
IPC-9850
Official Proposal
May 2001
22
Table 4-4 Terms Definition
Feeder assist time: A machine stop required to recover/replace a damaged feeder or "un-jam" a feeder.
Excludes parts replenishment. Measured from the time the operator starts assisting
the feeder until the time that the machine starts running. Excludes operator latency.
Excludes out of spec materials --such as sticking components in tape, delaminated
cover tape, etc.
Software assist time: The machine stops due to a program sequence error, but excludes operator-
programming mistakes.
Fiducial assist time: A machine stop required to find a fiducial that is unrecognizable or outside of the
capture range. Measured from the time the machine stops until the machine starts
running. Excludes operator latency.
Transport assist time: A machine stop required to correct a board jam. Measured from the time the machine
stops until the time the machine starts running. Excludes operator latency. Excludes
assists caused by a board that has been loaded into the machine upside down or
rotated.
Software failure time: A machine stop required by a software defect. Includes the time needed to abort
current operations, reboot (if required) and to restore all data and material to a
production ready condition. Measured from the time the machine stops until the time
the machine is ready to resume normal operation. Excludes operator (and supplier)
latency.
Hardware failure time: A machine stop required by a hardware failure of a factory approved part. Includes all
unscheduled calibrations, adjustments, troubleshooting and part replacements.
Excludes replacement of consumable or wear parts identified in the machine's
manual. Measured from the time the machine stops until the time the machine is
ready to resume normal operation. Excludes operator (and supplier) latency. Excludes
preventive maintenance time. Excludes failures of unauthorized third party parts or
materials.
Preventive maintenance time: Includes all inspections, cleaning, lubrication, adjustment, calibrations and part
replacements. Includes time required to replace all consumable and wear parts
identified in the machine's manual. Measured from the time preventive maintenance
activity begins until the machine is ready to resume normal operation. Excludes
operator (and supplier) latency. Excludes repair time.
IPC-9850
Official Proposal
May 2001
23
4.2.1 Mean Placements Between Assists (MPBA) –This is the average number of component placements between
assists.
Calculation Method The total component placements divided by the number of assists during those component
placements.
4.2.2 Mean Time To Recover from Assists (MTTR
a
) –This is the average time to correct an assist and return the
equipment to a condition where it can perform its intended function.
Calculation Method The sum of all assist recovery time (elapsed time, not necessarily total man hours) incurred
during a specified period (including equipment and process test time, but not including maintenance delay), divided
by the number of assists during that period.
4.2.3 Mean Placements Between Failures (MPBF) –This is the average number of component placements
between failures.
Calculation Method The total component placements divided by the total number of failures during those component
placements.
For statistical credibility, the MPBF claim must be no higher than one third of the number of placements completed.
4.2.4 Mean Time To Repair Failures (MTTR
f
) –This is the average time to correct a failure and return the
equipment to a condition where it can perform its intended function
Calculation Method The sum of all repair time (elapsed time, not necessarily total man hours) incurred during a
specified period (including equipment and process test time, but not including maintenance delay), divided by the
number of failures during that period.
4.2.5 Total Time- This is all time (at the rate of 24 hours/day, 7 days/week) during the period being measured.
4.2.6 Non-Scheduled Time -This is a period when the equipment is not scheduled to be utilized in production.
4.2.7 Operations Time -This is total time minus non-scheduled time.
4.2.8 Equipment Dependent Uptime –This is the percentage of operations time when a machine is in a condition to
perform its intended function. It includes productive, standby, and engineering time, and does not include any
portion of non-scheduled time.
Calculation Method The Equipment Dependent Uptime multiplied by 100 and divided by operations time.
Assists
of
#
PlacementsEquipment Total
=MPBA
Failures of #
PlacementsEquipment Total
=MPBF
Failures
of
#
TimeRepair Total
=
f
MTTR
Assists
of
#
TimeRecovery Total
=
a
MTTR