IPC-SM-840 establishes the requirements for evaluating both liquid and dry film solder mask materials. It provides a framework for testing how well these materials adhere to the board, resist solvents, and maintain electrical insulation. A key update in the current Revision E is the inclusion of requirements for flexible cover materials
The transition to lead-free soldering (RoHS compliance) drastically increased the thermal stress placed on solder masks. Standard solder paste reflow temperatures jumped from roughly 183°C (tin-lead) to upwards of 235°C-260°C (lead-free). If you are referencing an older version of the standard found in a random search, you might miss the specific thermal shock requirements added in Revision D and E to account for these higher temperatures.
If your company is an IPC member, you may have access to a corporate license or a discount on historical standards. Log into the IPC portal to check your entitlements. ipc-sm-840 pdf
The material must survive multiple exposures to molten solder (260°C for lead-free, historically 240°C for tin-lead) without blistering, cracking, or separating from the copper.
If you need the PDF for regulatory or legacy verification, purchase it legally from the IPC store. If you are designing a new product, move forward with IPC-4554 and simply reference the older standard for context. Remember: A solder mask is not just a pretty color; it is a critical safety and reliability component. Using the right standard—whether historical or current—ensures that your electronics will survive assembly and operate flawlessly in the field. Log into the IPC portal to check your entitlements
: Materials are tested to ensure they meet safety ratings, often aligning with UL 94 V-0 requirements. Understanding Classes: Class T vs. Class H
If you simply need the performance requirements rather than the historical document, use (the active standard). If you need a free summary, many PCB manufacturers publish "Capability Statements" that directly reference compliance with IPC-SM-840 Class H. You can request these from vendors like: so the callout persists.
Facilitates finer pitch designs and high-density packaging (BGA/SMT).
Test coupons are exposed to 85°C / 85% RH (relative humidity) for 7 days while under a DC bias. The standard sets minimum pass/fail thresholds (typically >100 Megohms).
Navigating IPC-SM-840: The Standard for PCB Solder Mask Reliability
Because their customers’ drawings are old. Many design engineers have not updated their CAD libraries since the 1990s, so the callout persists. Modern fabs automatically use 4554 but cross-reference SM-840 for customer comfort.