IPC-TM-650 EN 2022 试验方法-- - 第51页

Measurement Systems Analysis For Variables Data: Measurement Precision Calculator Version 1.0, August 2002 Introduction Welcome to the Measurement Precision Calculator. This workbook will help perform the calculations fo…

A graph showing only the relationship between the measurement variability and the spec limits is shown below. Here the

normal curve represents only the variability of a given measurement. The curve clearly consumes half the spec width. Place-

ment of the curve in the spec interval is arbitrary. The curve is formed by drawing it with a total width of six times the

R&r

Sometimes there is only one spec, and the table above will be blank. For those situations, the next table compares measure-

ment variability to the total observed variation.

The numbers in the table are again percentages, but this time percentages of total variation. In this example, the measure-

ment variation is 23% of the overall total observed variation. The same guidelines apply, except measurements would con-

sume less than 10% of the total variation. Unacceptable measurements would consume more than 30%. This example falls

in the gray zone in between; not good enough, with improvement recommended.

The ﬁnal metric in the scorecard provides a measurement tolerance. The stated value forms a 99% conﬁdence interval. The

tolerance is shown in this example:

A ‘‘conﬁdence interval’’ is one of those strange statistical concepts that ought to be easy to describe, but somehow become

garbled when translated from equation to English. Let us try to state it clearly:

We make a measurement to estimate the actual, but unknown, performance point of the product. There is a 99% chance that

the actual performance will be within ± the measurement tolerance of the measurement.

In this example, any given gasket measurement will have a tolerance of ± 0.111 mm. The real gasket thickness is within ±

0.111 mm of our measurement.

The ﬁnal step is to determine lessons learned from the MSA and document any changes to the test procedure. If the evalu-

ation indicates the test procedure needs to be improved, these improvement projects should be undertaken as soon as pos-

sible.

0.2 0.4 0.6 0.8 1.0 1.2 1.4

Spec

limits

Measurement

error

Comparison to Total Variation

% Repeatability 2.76653 Percent of total variability used by repeatability error

% Reproducibility

2.69817

Percent of total variability used by reproducibility error

% Measurement R&r

5.46469

Percent of total variability used by measurement error

Compared to the total variability, the precision of

this measurement:

Is adequate

Measurement Tolerance

Units

On the basis of this study, there is a 99% chance that

this interval around the measured product performance

will contain the actual product performance level.

+/- 0.111243938

Users

Guide

January

2003

Document

and

Correct

Measurement Systems Analysis For Variables Data:

Measurement Precision Calculator

Version 1.0, August 2002

Introduction

Welcome to the Measurement Precision Calculator. This workbook will help

perform the calculations for Measurement Precision Studies as described

in the IPC test method IPC-TM 1.9.

This software is useful in cases where the measurement data is recorded

as variables data and recoreded on a continuous scale.

Please refer to the test method before beginning the measurement precision study.

The test method defines the terms and equations used in detail.

Also refer to the User Guide for detailed instructions..

This workbook includes the following

- A blank spreadsheet to enter measurements

- A spreadsheet with example data

- A form for manual data entry, if desired.

- Further information on the K factors used in the calculations

The title cells on the spread sheet have been color coded to aid understanding.

The following is the color key:

Color

General title

Cells for user to enter data

Title cells for test condition related data

Title cells for data related to repeated readings

Title cells for sample related data

Title cell for calculated data

Usage

1 Scope

This method is to be used as a guideline for pre-

paring a metallographic specimen of printed boards. The fin-

ished microsection is used for evaluating the quality of the

laminate system and plated structures (plated-through holes,

solder joints, vias, etc.). The plated structures can be evalu-

ated for characteristics of the copper foils, plating, and/or

coatings to determine compliance with applicable perfor-

mance specification requirements.

Metallographic sample preparation is regarded by many as

essentially a highly developed skill; this method describes

those techniques that have been found to be generally

acceptable. It does not attempt to be so specific as to not

allow acceptable variations that can differentiate metallogra-

phers. Furthermore, the success of these techniques remains

highly dependent upon the skill of the individual metallogra-

pher.

Note: These microsection techniques are processes and are

intended as guidelines and thus variations are allowed.

Note: The use of the materials listed in Section 4 may be lim-

ited or forbidden in some environments. Please review the

Safety Data Sheet (SDS) for the materials being used.

1.1 Method A (Manual) Description

Manual metallo-

graphic preparation of sample(s).

1.2 Method B (Semi or Automatic) Description

Semi or

automatic metallographic preparation utilizing dedicated

microsection equipment to prepare multiple samples.

2 Applicable Documents

IPC-MS-810

Guidelines for High Volume Microsectioning

ASTM E 3

Standard Methods of Preparation of Metallo-

graphic Specimens

3 Test Specimens

A test coupon or printed board to be

inspected per the applicable performance specification, which

includes the features to be evaluated (i.e., plated holes or

laminate). This may require multiple microsections.

4 Apparatus or Material

4.1

Sample removal method (see IPC-MS-810 for the best

method to meet your needs).

4.2

Personal Protective Equipment (e.g., eye protection,

gloves)

4.3

Ventilation system (Fume Hood) in compliance with

material SDS (as required)

4.4

Mount molds.

4.5

Smooth, flat mounting surface.

4.6

Release agent (optional).

4.7

Sample supports (optional for Method A).

4.8

Sample alignment tools (Method B).

4.9

Metallographic wet grinding/polishing system or equip-

ment (as applicable).

4.10

Low magnification visual aid (reticle optional)

4.11

Metallographic microscope capable of minimum con-

struction integrity magnifications as specified in procurement

documentation.

4.12

Vacuum pump and desiccator or pressure pot

(optional).

4.13

Potting material (maximum cure temperature 93 °C

[200 °F]). (For discussion on selection of potting material refer

to IPC-MS-810.)

4.14

Sandpaper. Federation of European Producers of

Abrasives (FEPA)(ISO 6344) paper backed Silicon Carbide P

(coated) abrasive medium P80-P4000 (United States CAMI

(Coated Abrasive Manufacturers Institute) grit range: 80-1200.

4.15

Polishing Cloths. A hard, low, or no nap cloth for rough

and intermediate polishing, and a soft, woven, or medium nap

cloth for final polishing.

4.16

Oxide or colloidal silica polishing suspension (final pol-

ish, 0.3 - 0.04 µm [11.8 - 1.57 µin]). (Optional).

3000 Lakeside Drive, Suite 105N

Bannockburn, IL 60015-1249

IPC-TM-650

TEST METHODS MANUAL

Number

2.1.1

Subject

Microsectioning, Manual and Semi or Automatic

Method

Date

6/15

Revision

Originating Task Group

Microsection Subcommittee (7-12)

Material in this Test Methods Manual was voluntarily established by Technical Committees of IPC. This material is advisory only

and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this

material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement.

Equipment referenced is for the convenience of the user and does not imply endorsement by IPC.

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