IPC9850_Surface Mount Equipment Characterization.pdf - 第7页
IPC-9850 Official Proposal May 2001 7 Y dev refers to the placement error in the Y-direction direction (perpendicular to the “9850 Verification” label found on the Placement Verification Panel). θ θ dev refers to the rot…
IPC-9850
Official Proposal
May 2001
6
1.4.5.1 Equipment Measurement equipment that meets or exceeds the required GR&R and accuracy specification
limits under the specified evaluation procedures for a specified component type is acceptable.
Automated Optical CMM machines are currently favored by many placement equipment vendors and users due to
their measurement speed. The rapid measurement speed is required due the large number of measurements required
to attain statistically meaningful characterization results. Although this method has been demonstrated to work well,
significant limitations are recognized. The limitations restrict interpretation of the results to the actual SMT process.
Since CMMs were originally developed for a machine shop environment, their lighting systems and measurement
tools are not optimized for measuring surface mount components. The machines are applied to the placement
evaluation process by utilizing clear PVPs that make available high quality images on the CMM. The components
are mounted onto the PVP, are illuminated, and then their positions are measured.
Limitations of the CMMs are their cost and lack of mobility. CMMs are expensive since they utilize many features
that provide structural rigidity, precise position, and high quality imaging. They require delicate calibration and are
sensitive to changes in the environmental conditions, which makes them non-portable.
1.4.5.2 Reporting Measurement results are recorded on standardized forms. The Placement Performance Metric is
form IPC-9850-F1. This form serves two distinct functions. The first is to report the general performance by
machine model type and the second is to validate the performance of a specific machine by serial number. Values
for speed and accuracy that are simultaneously achievable are listed. Form IPC-9850-F1 is supported by the CMM
Capability to Evaluate Metric Parameters form, IPC-9850-F3, which is used to demonstrate the measurement
validity of the parameters presented in the Placement Performance Metric.
The Reliability Performance form (IPC-9850-F2) provides an indication of typical results determined from values
reported by users. Unlike the Placement Performance Metric, which cites guaranteed performance, the Reliability
Performance form merely conveys typical reliability levels for the machine model type based upon a nominal
amount of data collected by the placement machine supplier’s customers in their factories. But this reliability
performance form does establish a foundation upon which the industry can raise the reliability, availability and
maintainability of the surface mount equipment infrastructure.
1.5 Forms Reproducible copies of all required forms are provided in Section 7.
1.6 Data Methods
With regards to the statistical treatment of placement deviation data, we have assumed that deviations generally
follow normal (Gaussian) distributions. This may not always be the case. There is nothing inherently wrong with
data having some other distribution. However, depending upon the circumstances, it might mean that the
specification limits at the two prescribed Cpk limits (1.33 and 2.0) contain some percentage of data less than the
99.9968% and 99.9999% percentages normally associated with these Cpk limits. It would be prudent for the user to
verify that the machine has data that reasonably approximates a normal distribution if it is crucial to the user that the
machine's level of inaccurate placements precisely matches those associated with Cpks of 1.33 or 2.0.
1.7 Terms and Definitions
Additional terms and definitions are provided in Table 4-4 and 4.1.1 through 4.1.11.
Fiducials are markings on substrate materials --such as PWBs or glass-- that are utilized by the placement
equipment vision systems to locate the position and orientation of the substrate.
Component refers to surface mount parts which are utilizes in the construction of electronic devices.
Placement Error is defined as the physical distance between where the component was actually placed and where
the surface mount equipment was specified to place the component by the placement program data.
Slug refers to a NIST certified glass panel with etched image of a single Component and reference fiducials.
X
dev
refers to the placement error in the X-direction (parallel to the “9850 Verification” label found on the
Placement Verification Panel).
IPC-9850
Official Proposal
May 2001
7
Y
dev
refers to the placement error in the Y-direction direction (perpendicular to the “9850 Verification” label found
on the Placement Verification Panel).
θθ
dev
refers to the rotational placement error (about the component’s X-Y area centroid location).
Overhang refers to the portion of the lead’s width, at the lead’s tip, that extends off of the land’s edge. Overhang I
is due to placement error jointly caused by the X, Y, and θ deviations.
Assist is defined as an unplanned interruption that occurs during an equipment cycle where all three of the following
conditions apply:
• The interrupted equipment cycle is resumed through external intervention (e.g., by an operator or user, either
human or host computer).
• 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.
• There is no further variation from specifications of equipment operations.
Build Time - The amount of time it takes the machine to pick and place all the components. This time period
includes fiducial read time and nozzle change time if any.
Failure is defined as any unplanned interruption or variance from the specifications of equipment operation other
than assists. Specifically, some part of the placement machine has to be replaced or the machine had to be turned off
and then back on in order to continue production.
Net Throughput - The number of Components Per Hour (CPH) the machine can place on the verification PVP.
Preventive Maintenance (PM) is a machine stop required by the supplier's published PM schedule.
Repeatability is defined as one standard deviation of the placement error when placing multiple components upon
multiple boards.
Tact Time - The average time required to place a single component while maintaining the specified placement
process capability. Excludes transfer time, fiducial time and nozzle change time.
Total Tact Time - The time required to place all components on verification glass verification panel while
maintaining the specified placement process capability. Excludes Transfer Time, Fiducial Time and Nozzle Change
Time.
Transfer time – The total transport time in and out of the machine, excluding the time the panel spends in the work-
area.
• Movement in and out of work area
• Time to clamp/release the board in the work area
Land The termination areas on the PWB referred to by the IPC-T-50 Terms and Definitions as a portion of a
conductive pattern usually, but not exclusively, used for the connection and/or attachment of components, also
commonly referred to as pads.
1.8 Units of Measurement All dimensions in this document are provided in hard metric (SI) followed by soft
English/Imperial in brackets. All components are referenced as a metric definition, i.e. 1608C is equivalent to the
0603 (60milx30mil) component type.
2. Referenced Documents
IPC-A-610 Acceptability of Electronic Assemblies
IPC-SM-782 Surface Mount Design and Land Pattern Standard
IPC-T-50 Terms and Definitions for Interconnecting and Packaging Electronic Circuits
IPC-9850
Official Proposal
May 2001
8
SEMI E10-0699E Standard for Definition and Measurement of Equipment Reliability (Semiconductor Equipment
and Materials International 805 East Middlefield Road Mountain View, CA 94043-4080)
MSA-2 Measurement Systems Analysis Second Edition February 1995 published by AIAG (Automotive Industry
Action Group, 26200 Lahser Road Suite 200, Southfield MI 48034
IPC/EIA J-STD-001 Soldered Electrical and Electronic Assemblies standard (sometimes called the National
Soldering Standard)
3 Placement Performance Metric
3.1 Machine Performance Form IPC-9850-F1
This form (see 7 Forms) serves two distinct functions. One is to report the general performance by machine model
type. The second is to validate the performance of each machine shipped, as identified by serial number.
The top of the form is divided into two sections. At the top left is a region for identifying the vendor and machine
model. At the top right there is a region for use only when the form is utilized for performance validation:
• Serial Number
• Build Date and Time
The following information is reported in the body of the form, which is divided into four sections.
Section I informs of the Test Conditions during the build that generated the data reported in form Sections II, III and
IV. The conditions are:
• Number of Heads/Spindles
• Type of Heads/Spindles
• Type of Camera
• Number of Feeders/Trays
• Type of Nozzles
• Number of Nozzles
• Number of Panels Built
• Number of Parts Per Panel
and describe the hardware and software setup of the equipment for the reported results.
Section II presents the time-based parameters measured during the build cycle as components are placed. The
parameters are
• Build Time, seconds
• Transfer Time, seconds
• Tact Time, seconds
The Net Throughput (in CPH) also is attained from the time-based parameters.
Section III and IV present CMM measured and analyzed performance parameters attained for the panels populated
during the data collection for Section II while under the equipment setup of Section I:
• Repeatability (one standard deviation)
• Accuracy Spec. Limits for Cpk=1.33 for
• Accuracy Spec. Spec. Limits for Cpk=2.0
• Cpk for Termination-to-Land 50% Coverage
• Cpk for Termination-to-Land 75% Coverage
The Repeatability and Accuracy parameters are individually calculated for the X-axis, Y-axis, and θ rotation, while
the Termination-to-Land calculations integrate the X-axis, Y-axis, and θ rotation placement errors. See Section
3.4.3.2.2 (Cpk for Termination-to-Land Coverage) for details.
Appendix D provides a guide for two possible methods of measuring the center locations of the components to attain
the measurement error.