JOINT INDUSTRY STANDARD
Moisture/Reflow Sensitivity Classification
for Nonhermetic Solid State Surface
Mount Devices IPC/JEDEC J-STD-020C Supersedes IPC/JEDEC J-STD-020B
Table of Contents
1PURPOSE (1)
1.1Scope (1)
1.2Background (1)
2APPLICABLE DOCUMENTS (1)
2.1JEDEC Solid State Technology Associaton (1)
2.2IPC (2)
2.3Joint Industry Standards (2)
3APPARATUS (2)
3.1Temperature Humidity Chambers (2)
3.2Solder Reflow Equipment (2)
3.2.1Full Convection(Preferred) (2)
3.2.2Infrared (2)
3.3Ovens (2)
3.4Microscopes (2)
3.4.1Optical Microscope (2)
3.4.2Scanning Acoustic Microscope (2)
3.5Cross-Sectioning (2)
3.6Electrical Test (2)
3.7Weighing Apparatus(Optional) (2)
4CLASSIFICATION/RECLASSIFICATION (3)
4.1Compatibility with Pb-Free Rework (3)
4.2Reclassification (3)
5PROCEDURE (4)
5.1Sample Requirements (4)
5.1.1Reclassification(Qualified Package Without
Additional Reliability Testing) (4)
5.1.2Classification/Reclassification and Rework (4)
5.2Initial Electrical Test (4)
5.3Initial Inspection (4)
5.4Bake (5)
5.5Moisture Soak (5)
5.6Reflow (5)
5.7Final External Visual (5)
5.8Final Electrical Test (5)
5.9Final 56CRITERIA (6)
6.1Failure Criteria (6)
6.2Criteria Requiring Further Evaluation (7)
6.2.1Delamination (7)
6.3Failure Verification (8)
7MOISTURE/REFLOW SENSITIVITY
CLASSIFICATION (8)
8OPTIONAL WEIGHT GAIN/LOSS ANALYSIS (8)
8.1Weight Gain (8)
8.2Absorption Curve (8)
8.2.1Read Points (8)
8.2.2Dry Weight (8)
8.2.3Moisture Soak (8)
8.2.4Readouts (8)
8.3Desorption Curve (9)
8.3.1Read Points (9)
8.3.2Baking (9)
8.3.3Readouts (9)
9ADDITIONS AND EXCEPTIONS (9)
Annex A (10)
Figures
Figure5-1Classification Reflow Profile (6)
Tables
Table4-1SnPb Eutectic Process–Package Peak
Reflow Temperatures (3)
Table4-2Pb-free Process–Package Classification
Reflow Temperatures (3)
Table5-1Moisture Sensitivity Levels (5)
Table5-2Classification Reflow Profiles (6)
Moisture/Reflow Sensitivity Classification for
Nonhermetic Solid State Surface Mount Devices
1PURPOSE
The purpose of this standard is to identify the classification level of nonhermetic solid state surface mount devices(SMDs) that are sensitive to moisture-induced stress so that they can be properly packaged,stored,and handled to avoid damage during assembly solder reflow attachment and/or repair operations.
This standard may be used to determine what classification/preconditioning level should be used for SMD package qualifi-cation.Passing the criteria in this test method is not sufficient by itself to provide assurance of long-term reliability.
1.1Scope This classification procedure applies to all nonhermetic solid state Surface Mount Devices(S
MDs)in packages, which,because of absorbed moisture,could be sensitive to damage during solder reflow.The term SMD as used in this document means plastic encapsulated surface mount packages and other packages made with moisture-permeable materials. The categories are intended to be used by SMD producers to inform users(board assembly operations)of the level of mois-ture sensitivity of their product devices,and by board assembly operations to ensure that proper handling precautions are applied to moisture/reflow sensitive devices.If no major changes have been made to a previously qualified SMD package, this method may be used for reclassification according to4.
2.
This standard cannot address all of the possible component,board assembly and product design combinations.However,the standard does provide a test method and criteria for commonly used technologies.Where uncommon or specialized compo-nents or technologies are necessary,the development should include customer/manufacturer involvement and the criteria should include an agreed definition of product acceptance.
SMD packages classified to a given moisture sensitivity level by using Procedures or Criteria defined within any previous version of J-STD-020,JESD22-A112(rescinded),IPC-SM-786(superseded)do not n
eed to be reclassified to the current revision unless a change in classification level or a higher peak reflow temperature is desired.
Note:If the procedures in this document are used on packaged devices that are not included in this specification’s scope, the failure criteria for such packages must be agreed upon by the device supplier and their end user.
1.2Background The vapor pressure of moisture inside a nonhermetic package increases greatly when the package is exposed to the high temperature of solder reflow.Under certain conditions,this pressure can cause internal delamination of the packaging materials from the die and/or leadframe/substrate,internal cracks that do not extend to the outside of the package,bond damage,wire necking,bond lifting,die lifting,thinfilm cracking,or cratering beneath the bonds.In the most severe case,the stress can result in external package cracks.This is commonly referred to as the‘‘popcorn’’phenomenon because the internal stress causes the package to bulge and then crack with an audible‘‘pop.’’SMDs are more susceptible to this problem than through-hole parts because they are exposed to higher temperatures during reflow soldering.The rea-son for this is that the soldering operation must occur on the same side of the board as the SMD device.For through-hole devices,the soldering operation occurs under the board that shields the devices from the hot solder.
2APPLICABLE DOCUMENTS
2.1JEDEC Solid State Technology AssociatIon1
JESD22-A120Test Method for the Measurement of Moisture Diffusivity and Water Solubility in Organic Materials Used in Integrated Circuits
JESD22-A113Preconditioning Procedures of Plastic Surface Mount Devices Prior to Reliability Testing
JESD47Stress Test Driven Qualification Specification
JESD-625Requirements for Handling Electrostatic Discharge Sensitive(ESD)Devices
IPC/JEDEC J-STD-020C
2.2IPC2
IPC-TM-650Test Methods Manual3
2.1.1Microsectioning
2.1.1.2Microsectioning-Semi or Automatic Technique Microsection Equipment
2.3Joint Industry Standards4
J-STD-033Standard for Handling,Packing,Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices
J-STD-035Acoustic Microscopy for Nonhermetic Encapsulated Electronic Components
3APPARATUS
3.1Temperature Humidity Chambers Moisture chamber(s),capable of operating at85°C/85%RH,85°C/60%RH, 60°C/60%RH,and30°C/60%RH.Within the chamber working area,temperature tolerance must be±2°C and the RH tolerance must be±3%RH.
3.2Solder Reflow Equipment
3.2.1Full Convection(Preferred)Full convection reflow system capable of maintaining the reflow profiles required by this standard.
3.2.2Infrared Infrared(IR)/convection solder reflow equipment capable of maintaining the reflow profiles required by this standard.It is required that this equipment use IR to heat only the air and not directly impinge upon the SMD Packages/ devices under test.
Note:The moisture sensitivity classification test results are dependent upon the package body temperature(rather than the mounting substrate and/or package terminal temperature).
3.3Ovens Bake oven capable of operating at125+5/-0°C.
3.4Microscopes
3.4.1Optical Microscope Optical Microscope(40X for external and100X for cross-section exam).
3.4.2Scanning Acoustic Microscope Scanning acoustic microscope with C-Mode and Through Transmission capability and capable of measuring a minimum delamination of5%of the area being evaluated.
Note1:The scanning acoustic microscope is used to detect cracking and delamination.However,the presence of delami-nation does not necessarily indicate a pending reliability problem.The reliability impact of delamination must be established for a particular die/package system.
Note2:Refer to IPC/JEDEC J-STD-035for operation of the scanning acoustic microscope.
3.5Cross-Sectioning Microsectioning equipment as recommended per IPC-TM-650,Methods2.1.1,2.1.1.2or other applicable document.
3.6Electrical Test Electrical test equipment with capabilities to perform appropriate testing on devices.
3.7Weighing Apparatus(Optional)Weighing apparatus capable of weighing the package to a resolution of1microgram. This apparatus must be maintained in a draft-free environment,such as a cabinet.It is used to obtain absorption and des-orption data on the devices under test(see8).
2.Current and revised IPC Test Methods are available through IPC-TM-650subscription and on the IPC website
4CLASSIFICATION/RECLASSIFICATION
Refer to 4.2for guidance on reclassification of previously qualified/classified SMDs.
Engineering studies have shown that thin,small volume SMD packages reach higher body temperatures during reflow sol-dering to boards that have been profiled for larger packages.Therefore,technical and/or business issues normally require thin,small volume SMD packages (reference Table 4-1,4-2)to be classified at higher reflow temperatures.
Note 1:Previously classified SMDs should only be reclassified by the manufacturer.Users should refer to the ‘‘Moisture Sensitivity’’label on the bag to determine at which reflow temperature the SMD packag
es were classified.
Note 2:Level 1SMD packages should be considered to have a maximum reflow temperature of 220°C unless labeled as capable of reflow at other temperatures.
Note 3:If supplier and user agree,components can be classified at temperatures other than those in Table 4-1and 4-2.
4.1Compatibility with Pb-Free Rework
Unless otherwise specified by the device manufacturer,a Pb-free component
(classified per Table 4.2),shall be capable of being reworked at 260°C within eight hours of removal from dry storage or bake,per J-STD-033.To verify this capability for a component classified at a temperature below 260°C,a sample of the size per 5.1.2shall be soaked per Level 6conditions (see Table 5-1)using a Time on Label (TOL)of eight hours,and reflowed at a classification temperature of 260°C.All devices in the sample shall pass electrical test and have a damage response per 6.1and 6.2not greater than that observed for the same package at its rated MSL level.A component rated at 260°C does not require this rework compatibility verification.
4.2Reclassification
SMD packages previously classified to a moisture sensitivity level and reflow peak/classification
temperature may be reclassified if the damage response (delamination/cracking)at the more severe condition for items listed in 6.1and 6.2is less than,or equal to the damage response at the original classification condition.
If no major changes have been made to a previously qualified SMD package,this method may be used for reclassification to an improved level (longer floor life)at the same reflow temperature.The reclassification level cannot be improved by more than one level without additional reliability testing.Reclassification to Level 1requires additional reliability testing.If no major changes have been made to a previously qualified SMD package,this method may be used for reclassification at a higher reflow temperature providing the moisture level remains the same or degrades to a more sensitive level.
Table 4-1
SnPb Eutectic Process –Package Peak Reflow Temperatures
Package Thickness
Volume mm 3
<350
Volume mm 3
≥350
<2.5mm 240+0/-5°C 225+0/-5°C ≥2.5mm
225+0/-5°C
225+0/-5°C
Table 4-2
Pb-free Process –Package Classification Reflow Temperatures
Package Thickness
Volume mm 3
<350
Volume mm 3350-2000
Volume mm 3
>2000
<1.6mm 260+0°C *260+0°C *260+0°C *1.6mm -2.5mm
260+0°C *250+0°C *245+0°C *≥2.5mm
250+0°C *
245+0°C *
245+0°C *
*Tolerance:The device manufacturer/supplier shall assure process compatibility up to and including the
stated classification temperature (this means Peak reflow temperature +0°C.For example 260°C+0°C)at the rated MSL level.
Note 1:The profiling tolerance is +0°C,-X °C (based on machine variation capability)whatever is required to control the profile process but at no time will it
exceed -5°C.The producer assures process compatibility at the peak reflow profile temperatures defined in Table 4.2.
Note 2:Package volume excludes external terminals (balls,bumps,lands,leads)and/or nonintegral heat sinks.
Note 3:The maximum component temperature reached during reflow depends on package thickness and volume.The use of convection reflow processes
reduces the thermal gradients between packages.However,thermal gradients due to differences in thermal mass of SMD packages may still exist.
Note 4:Components intended for use in a ‘‘lead-free’’assembly process shall be evaluated using the ‘‘lead free’’classification temperatures and profiles
defined in Tables 4-1,4.2and 5-2whether or not lead free.
IPC/JEDEC J-STD-020C
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