IPC-SM-840C - Dynamix Technology

1 The Institute for Interconnecting IPC-SM- 840c . and Packaging Electronic Circuits Qualification and Performance of Permanent Solder Mask IPC-SM- 840c A standard developed by the Institute for Interconnecting January 1996 and Packaging Electronic Circuits Supersedes IPC-SM-840B 2215 Sanders Road Tel 847 May 1988 Northbrook, Illinois Fax 847 60062-6135 URL: January 1996 IPC-SM840C. Table of Contents SCOPE AND DESIGNATION .. 1 Resistance to Solvents, Cleaning Agents, Scope .. 1 and Fluxes .. 6. 1 Resistance to Solvents and Cleaning Agents .. 6. 1 Resistance to Assembly Process and Presentation.

2 1 Chemistry .. 6. Hydrolytic Stability/Aging .. 6. APPLICABLE DOCUMENTS .. 2 Flammability .. 6. 2 Class 6. Underwriters' Laboratories .. 2 Class T .. 6. ASTM .. 2 Soldering Requirements .. 6. REQUIREMENTS .. 2 Solderability .. 6. Terms and 2 Resistance to Solder .. 7. Bleeding .. 2 Electrical Requirements .. 7. 2 Dielectric Strength .. 7. Hydrolytic 2 Insulation Resistance .. 7. Skipping .. 3 Environmental Requirements .. 7. Solder Ball .. 3 Moisture and Insulation Resistance .. 7. Webbing .. 3 Electrochemical Migration .. 7. Wrinkling .. 3 Thermal 7. 3 QUALITY ASSURANCE PROVISIONS .. 7.

3 Qualification/Conformance .. 3 Responsibility for 7. Solder Mask Material Property Evaluation Test Equipment and Inspection Facilities .. 8. and 3 Categories of Inspection .. 8. Solder Mask/IPC-B-25A Test Board System Materials 8. 3. Standard Laboratory 8. Solder Mask/Production Board Process Permissible Temperature Variation in Qualification 3. Environmental Chambers .. 8. 3. Reference 8. Formulation Change .. 3. Qualification 8. 4. Sample 8. Shelf Life .. 4. Inspection Routine .. 8. 4. 8. Cure .. 4. Quality Conformance 8. Non-Nutrient .. 5. Inspection of Product for Delivery .. 8. Design.

4 5. Inspection of Solder Mask Properties .. 10. Visual Requirements .. 5. Preparation of Specimens for Test .. 10. Touch-up .. 5. Preparation Prior to 10. Dimensional 5. Coating .. 10. Physical Requirements .. 5. 10. Pencil 5. Adhesion .. 5 PREPARATION OF SOLDER MASK MATERIAL. FOR DELIVERY .. 10. Adhesion to Rigid Printed Wiring .. 5. Adhesion to Flexible Printed Wiring .. 5 NOTES .. 10. Via Protection .. 6 Specifying Solder Mask on Printed Wiring Nomenclature 6 11. Conformal Coating Adhesion .. 6 Special 11. Machinability .. 6 Assorted Methods for Monitoring or Chemical Requirements .. 6 Controlling Cure of Solder 11.

5 Iii IPC-SM840C January 1996. Solder Mask 12. Formulation Change .. 13. Ionics .. 13. Hole Plugging Via Protection .. 14. Figures Figure 1 IPC-B-25A .. 12. Figure 2 Test Coupon ( Y'' Configuration).. 12. Tables Table 1 Requirements of Qualification/Conformance .. 4. Table 2 Adhesion to Rigid Boards .. 5. Table 3 Resistance to Solvents and Cleaning 6. Table 4 Moisture & Insulation 7. Table 5 Electrochemical Migration .. 8. Table 6 Thermal Shock Conditions .. 8. Table 7 Summary of Criteria for Qualification/. Conformance .. 9. Table 8 Sample Requirements/Suggested Test Sequence from Table 1, Column A.

6 10. Table 9 Sample Requirements/Suggested Test Sequence .. 10. Table 10 Sample Requirements/Suggested Test Sequence for Table 1, Column C .. 11. iv January 1996 IPC-SM- 840c . Qualification and Performance of Permanent Solder Mask SCOPE AND DESIGNATION requirements can be required as agreed upon between the Scope This standard has been designed and con- solder mask vendor and the board fabricator, or between structed with the intent of obtaining the maximum informa- the board fabricator and end user. tion about and confidence in the solder mask material This document assumes that the mask is processed and under evaluation with the minimum of test redundancy.

7 Cured per the manufacturer's recommended process. The (See ) curing of the solder mask material that has been applied to This standard covers: printed boards shall be in accordance with those conditions specified by the solder mask vendor for that product or a The evaluation and conformance of permanent solder qualified alternate method as agreed to between the board mask material properties (Table 1, Column A). fabricator and the end user. When (other) alternate methods The qualification of the solder mask/standard IPC-B- are used, the board fabricator has full responsibility for the 25A test board (Table 1, Column B).

8 Performance of the solder mask. The qualification assessment of the solder mask/. production board process (Table 1, Column C). Classes This specification provides classes of requirements to reflect functional performance require- For purposes of this specification, the term solder mask'' ments and testing severity based on industry/end use is used herein when referring to any type of permanent requirements. polymer coating material applied prior to assembly, but excluding marking (legend) inks and temporary hole plug- Note: The reference of a single class does not preclude ging materials.

9 Invoking or allowing specific requirements defined in other Purpose This standard enables a vendor to evaluate classes. solder mask, and express the characteristics it possesses, T Telecommunication (Includes computers, telecommu- when tested in a standard board system according to the nication equipment, sophisticated business machines, test methods and conditions contained in this document. It instruments, and certain non-critical military applica- also enables a printed board designer, manufacturer, and/or tions.) Solder mask on boards in this class is suitable user to jointly qualify a production board process using the for high performance commercial and industrial prod- test methods and conditions contained in this document ucts in which extended performance life is required based on end use and environmental reliability require- but for which interrupted service is not life threaten- ments.

10 Quality conformance of production boards shall be ing. evaluated in accordance with IPC-RB-276. H High Reliability/Military (Includes that equipment The materials described herein are intended for use on where continued performance is critical, equipment printed boards in order to provide a solder mask to prevent down-time cannot be tolerated and/or the equipment solder bridging, and/or for the retardation of electromigra- is a life support item.) Solder mask on boards of this tion and other forms of conductive growth, and/or for the class is suitable for applications where high levels of physical protection of the printed board.