1、 EIA STANDARD Test Method Electronic Passive Components Exposure to Atmospheric Sulfur EIA-977 February 2017 Electronic Components Industry Association ANSI/EIA-977-2017 Approved: February 28, 2017 EIA-977 NOTICE EIA Engineering Standards and Publications are designed to serve the public interest th
2、rough eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards and Publications sh
3、all not in any respect preclude any member or nonmember of ECIA from manufacturing or selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Publications preclude their voluntary use by those other than ECIA members, whether the Standard is
4、to be used either domestically or internationally. Standards and Publications are adopted by ECIA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, ECIA does not assume any liability to any patent owner, nor does it assume any obligation whatever to p
5、arties adopting the Standard or Publication. This EIA Standard is considered to have International Standardization implications, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the EIA Standard and the IEC document can be ma
6、de. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations
7、 before its use. (From Standards Proposal No. 5317, formulated under the cognizance of the P-1 Committee on EIA National Resistive Devices Standards). Published by Electronic Components Industry Association 2017 EIA Standards however, the reagent may potentially be used for multiple tests by using t
8、he corrosion of the silver control specimen as an indicator that the EIA-977 Page 2 reagent must be replaced. If the control specimen does not blacken (tarnish) from sulfur exposure within 24 hours (per the definition in Section 4.5), the reagent must be replaced. 3.5. Test Container Any convenientl
9、y-sized vessel of glass, polycarbonate, stainless steel (or any other material) that is not affected by sulfur vapor and elevated temperatures may be used as the test container. The size of the test samples will dictate the required size of the container. For small components such as chip resistors,
10、 a glass desiccator of 9 to 10L capacity will be sufficient. The vessel does not need to be hermetically sealed and may have a small vent opening (1 to 4 mm diameter hole) to allow equalization of pressure when elevated temperatures are present. 3.5.1. Large test containers Larger vessels may be req
11、uired to accommodate test boards and Printed Circuit Board Assemblies (PCAs). If a large test container is used and the silver coupon does not blacken (tarnish) from sulfur exposure within 24 hours (per the definition in Section 4.5), a larger diameter Petri dish and additional sulfur may be needed
12、(Sections 5.1 and 5.2). 3.6 Convection Oven or Hot Plate A convection oven or hot plate may be used to maintain the required temperature inside the test container. 3.7 Thermocouples Thermocouples are used to monitor and control the temperature inside the test container. 3.8 Electrical Measurement Te
13、st Setup A resistance bridge or multi-meter and appropriate test probes capable of providing component electrical measurements within specified tolerances. This setup shall apply 5% of the components primary rating up to 50mW maximum (e.g., power for resistors, voltage for capacitors, current for in
14、ductors, etc.). 3.9 Microscope An optical microscope capable of up to 50X magnification. EIA-977 Page 3 Figure 1: Typical Test Setup 4. GENERAL PROCEDURE 4.1. Choice of test procedure The user and supplier must agree as to which of the two sets of test conditions will be applied, A or B. 4.2. Mounti
15、ng Unless otherwise specified in the individual specification or by customer request, test specimens shall be mounted to a printed wiring test board. If the components are to be placed as loose samples inside the test container, the surface of interest (typically those containing silver) should have
16、 unobstructed exposure to the sulfur environment. 4.3. Test sample documentation All relevant parameters from the component placement and soldering operation shall be recorded, including but not limited to: solder and flux materials, soldering temperature or profile, and component placement method.
17、4.4. Test sample cleaning After the components are soldered to the printed wiring board, the test specimens shall be cleaned in order to remove contamination that might affect the corrosion resistance results of the component itself. Cleaning requirements and conditions shall be adequate to remove a
18、ll residual flux and ionic contamination. The cleaning requirements and conditions may be AABUS (as agreed by user and supplier). 4.5. Control sample A silver coupon sample shall be suspended in the test container by a nylon line or other non-corroding material during the test to confirm the severit
19、y of the environment. EIA-977 Page 4 4.6. Initial Measurements Unless otherwise specified, initial measurements of the samples to be tested shall be made after mounting to the test board and those measurements shall be recorded. It is expected that the initial measurement of each sample unit will be
20、 within the specified data sheet electrical parameters. 4.7. Exposure The samples shall be placed in the test container and subjected to the test conditions according to Condition A (Section 5.1) or B (Section 5.2) chosen from Table 1 below. The parameters given for each test condition are default p
21、arameters. Deviations to the given parameters shall be as agreed by user and supplier and shall be documented in the test report. Table 1 Test Conditions - Resistance to Environmental Sulfur 1.Test conditions based on modification of ASTM B 809. Test Parameters A1BTemperature 60 2C (140F3.6F) 105C 2
22、C (221F3.6F)HumidityDuration 480 Hours 750 hoursReagentAmount of ReagentComponent Sample Size22 units. The case size to be qualified will be 0402 or smallest size available larger than 0402 or AABUS (As Agreed By User and Supplier).15 units each from 3 different production lots (of the same style, t
23、ermination design and manufactured under the same process and conditions with the same materials. ) The case size to be qualified will be 0402 or smallest size available larger than 0402 or AABUS (As Agreed By User and Supplier).Sample Nominal Component ValueSample Tolerance Nominal tolerance to be
24、qualified. Nominal tolerance to be qualified.Mounted on PCB Yes or AABUS Yes or AABUSFailure CriteriaTest ConditionsA) Using 50X magnification, any Ag2S crystals present on any electrode, termination or component surface, OR B) Shift in component electrical specifications outside datasheet electrica
25、l parameters. Thus a resistance shift of 1% for a 1% tolerance component or 5% for a 5% tolerance component is considered a failure. Passive components (resistors, capacitors, inductors and all others) must meet all specified datasheet electrical parameters.The sulfur shall be placed on a tray at th
26、e bottom of the chamber or on the base of the chamber. Cover the tray or base of the chamber with a bed of sulfur to 10 mm depth minimum. The greater the amount of sulfur placed in the chamber, the faster the sulfur in the chamber air will reach equilibrium.Sulfur, Sublimed (Flowers of Sulfur, or Fo
27、S). Most appropriate component value for the series being qualified (for resistors, this is the lowest available resistance) or AABUSNot applicableEIA-977 Page 5 5. SPECIFIC TEST PROCEDURES 5.1. Test Condition “A” 5.1.1. Test Container Temperature Control 5.1.1.1. It is recommended that the test con
28、tainer temperature be controlled by placing it in a larger convection oven. 5.1.1.2. Thermocouples connected to the temperature controller should be placed in close proximity to the test samples. 5.1.1.3. Flat heating elements (hot plate heaters) may be used on the exterior of the test container if
29、the test container temperature can be controlled to 2C consistently throughout the test container. 5.1.1.4. It is highly recommended that proportional temperature controllers with safety temperature limit shutoff be used for heating larger test containers. 5.1.2. Test container humidity is not activ
30、ely controlled because the formation of silver sulfide (Ag2S) occurs independent of the relative humidity. 5.1.3. Samples shall be exposed for 480 hours in the test container maintained at 60C2C (140F3.6F). 5.1.4. Monitoring control sample 5.1.4.1. The silver coupon control sample shall be visually
31、inspected (if possible, from outside of the test container) 24 hours after a test is begun. 5.1.4.2. The silver coupon must blacken (tarnish) from exposure to sulfur within 24 hours. 5.1.4.3. If the silver coupon does not completely blacken (tarnish) from sulfur exposure within 24 hours, additional
32、or fresh sulfur shall be added and the test shall be restarted. 5.1.4.4. The silver coupon shall remain in the test container for the duration of the test to avoid disrupting the equilibrium within the container. 5.1.5. Applied bias 5.1.5.1. Bias shall not be applied to any test sample during the te
33、st. 5.1.5.2. If component measurements are being used for sample monitoring and/or inspection, the applied voltage must not cause local heating of the test component because of the strong effect of temperature on the sulfuration chemical reaction and local sulfur vapor concentration. The applied pow
34、er to a resistor shall not be greater than a value that exceeds the smaller of 50 mW of power or 5% of the test samples rated power. 5.1.6. Sample Inspection and Testing 5.1.6.1. After exposure, components shall be examined using a microscope with adjustable magnifications to 50X. EIA-977 Page 6 5.1
35、.6.1.1. Higher magnifications may be necessary, including the use of scanning electron microscope, for more critical applications. 5.1.6.1.2. Any observable growths of silver sulfide crystals (Ag2S) must be recorded. 5.1.6.2. All components shall be tested for DC resistance or other relevant passive
36、 component datasheet electrical parameters, and the measurements recorded. 5.1.6.3. Failure criteria 5.1.6.3.1. Microscopic inspection at 50X reveals the presence of any amount of Ag2S crystals on any electrode, termination or component surface. 5.1.6.3.2. Passive components (resistors, caps, induct
37、ors and all others) must meet all specified datasheet electrical parameters. The change in DC resistance is greater than the nominal tolerance. (For instance, a resistance shift (R) of 1% for 1% tolerance component, or a shift of 5% for 5% tolerance.) 5.1.6.3.3. A change in component electrical para
38、meters due to printed wiring board degradation shall not be considered a failure and shall be confirmed by directly measuring the test sample. 5.2. Test Condition “B” 5.2.1. Test Container Temperature Control 5.2.1.1. It is recommended that the test container temperature be controlled by placing it
39、in a larger convection oven. 5.2.1.2. Thermocouples connected to the temperature controller should be placed in close proximity to the test samples. 5.2.1.3. Flat heating elements (hot plate heaters) may be used on the exterior of the test container if the test container temperature can be controlle
40、d to 2C consistently throughout the test container. 5.2.1.4. It is highly recommended that proportional temperature controllers with safety temperature limit shutoff be used for heating larger test containers. 5.2.2. Test container humidity is not actively controlled because the formation of silver
41、sulfide (Ag2S) occurs independent of the relative humidity. 5.2.3. Samples shall be exposed for 750 hours in a test container maintained at 105C2C (221F3.6F). 5.2.4. Monitoring control sample 5.2.4.1. The silver coupon control sample shall be visually inspected (if possible, from outside of the test
42、 container) 24 hours after a test is begun. 5.2.4.2. The silver coupon must blacken (tarnish) from exposure to sulfur within 24 hours. EIA-977 Page 7 5.2.4.3. If the silver coupon does not completely blacken (tarnish) from sulfur exposure within 24 hours, additional or fresh sulfur shall be added an
43、d the test shall be restarted. 5.2.4.4. The silver coupon shall remain in the test container for the duration of the test to avoid disrupting the equilibrium within the container. 5.2.5. Applied bias 5.2.5.1. Bias shall not be applied to any test sample during the test. 5.2.5.2. If resistance measur
44、ements are used for sample monitoring and/or inspection, the applied power must not cause local heating of the test component because of the strong effect of temperature on the sulfuration chemical reaction and local sulfur vapor concentration. The applied power to a resistor shall not be greater th
45、an a value that exceeds the smaller of 50 mW of power or 5% of the test samples rated power. 5.2.6. Sample Inspection and Testing 5.2.6.1. All components shall be tested for DC resistance or other relevant passive component datasheet electrical parameters, and the measurements recorded. 5.2.6.2. Fai
46、lure criteria 5.2.6.2.1. Microscopic inspection at 50X reveals the presence of any amount of Ag2S crystals on any electrode, termination or component surface. 5.2.6.2.2. Passive components (resistors, caps, inductors and all others) must meet all specified datasheet electrical parameters. The change
47、 in DC resistance is greater than the nominal tolerance. (For instance, a resistance shift (R) of 1% for 1% tolerance component, or a shift of 5% for 5% tolerance.) 5.2.6.2.3. A change in component electrical parameters due to printed wiring board degradation shall not be considered a failure and sh
48、all be confirmed by directly measuring the test sample. 6. DETAILS TO BE SPECIFIED The following details shall be specified in the referencing document: 6.1. Test condition to be used (A or B) 6.2. Number of samples 6.3. Sample nominal resistance value or passive component parameter(s) being monitor
49、ed 6.4. Sample tolerance 6.5. Mounted on PCB or not 6.6. Failure criteria EIA-977 Page 8 7. DOCUMENTATION Documentation shall contain the details specified and any exceptions: 7.1. Title of the test 7.2. Specimen description, including test fixturing if applicable (photographs may be used) 7.3. Test equipment used, and date of last and next calibration 7.4. The test condition used 7.5. Failure criteria 7.6. Values and observations 7.7. Name of operator and test date ECIA Document Improvement Proposal If in the review
