IPC9850_Surface Mount Equipment Characterization.pdf - 第23页
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 n…
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
IPC-9850
Official Proposal
May 2001
24
4.2.9 Preventative Maintenance (PM) Time
This is the amount of time required for preventative maintenance as specified by the machine supplier. This metric
will be based on the maintenance routines that are required each year in order to keep the machine in a warranted
condition and how long those routines take for a 6000 hour period.
Calculation Method Multiply the amount of time required for each PM procedure by the number of times it is
required in 6000 hours and add these up for a grand total.
4.2.10 Mispick Rate (in PPM) This is the frequency with which a component was not picked or picked incorrectly,
even if recovery handled the problem. Mispicks include both pickup failures and vision failures, but excludes
components exhaust.
Pickup defects will be handled in a manner similar to placement defects. Pickup defects are categorized as vacuum
failures or vision failures. While many suppliers have various auto-recovery routines that prevent a pickup defect
from resulting in a missing component placement defect, this type of defect has still been deemed worthy of tracking
and reporting due to its impact on the assembly process. Pickup defects cause a reduction in net CPH and the
unnecessary rejection and scrapping of good parts.
The number of mispicks that occur during the 4400 part placements made to determine placement defect rate will be
recorded on Form IPC-9850-F2. The number of pickup defects made during this process for the past 20 machines
will be reported, from which a point estimate for pickup defects in PPM can be made.
Measurement Procedure Clear the Mispick counters in the machine. Empty the reject bin. Record the relative
humidity. Run the attribute defect test (place 4,400 components). Record the vacuum failure, and vision failure
counter values. Examine the components found in the reject bin and count the defective components.
Calculation Method The total pickup attempts minus total number of placements minus the number of defective
components divided by total pickup attempts minus defective components, multiplied by one million to obtain ppm.
Mispick Rate =1,000,000 * (Total Pickup Attempts)- (Total Number of Placements) –(Number of Defective Components)
(Total Pickup Attempts) –(Number of Defective Components)
4.3 Reporting Sites This is the number of machine sites included in the reliability metric calculations.
4.3.1 Number of Machines This is the number of individual machines included in the reliability metric calculations.
4.3.2 Total Number of Placements This is the number of individual machine placements included in the reliability
metric calculations.
4.3.3 Total Pickup Attempts This is the number of times the nozzles attempted to pick components.
5 Measurement Capability Verification –Form IPC-9850-F3
Form IPC-9850-F3 functions as a tool for demonstrating the measurement capability of the measurement equipment
used to generate the parameter values for the Placement Performance Metric (form IPC-9850-F1). The measurement
capability information presented on the form shall be gathered and reported according to this standard, and shall
reflect the performance of the measurement equipment used in the machine performance analysis. The reported
information should be acquired no more than 90 days prior to the machine performance study.
The parameters of this metric shall evaluate the measurement system’s ability to accurately measure the test
vehicles produced during the machine performance evaluation analysis in a repeatable and reproducible manner.
This evaluation shall be made for each component type and yields results about the measurement capabilities of the
CMM along the same axes as reported by the placement performance metric. exceed The specification limits
reported in the performance reporting form shall never be smaller than the larger of the GR&R and accuracy CMM
specification limits per component type. Suppliers that add additional component types to the Placement
Performance Metric shall also report their measurement capabilities for the same component types.