This article is part of a series of documents aimed at providing education and information to all Prime customers and anyone who uses printed circuit boards.
We want to provide some guidance on how to reduce the phenomenon of “”Delamination in printed circuit boards “”.
First of all, it “is important to know that Printed Circuit Boards are manufactured using composite material (FR4 and its variants). This is a highly HYGROSCOPIC material, which means” it is “particularly sensitive to” environmental humidity “, regardless of the packaging” method.
Any “moisture” that is not eliminated will “transform into vapor during the soldering phases, causing cracks, blistering, delamination, blowholes, and microcavities” in the most “sensitive areas of the” assembly.
To prevent this phenomenon, it “is helpful to have appropriate methods for” packaging, storage, and potential drying of the printed circuit board before entering production.
It “is good practice to consider the printed circuit board as a”“perishable”“material; Prime suggests not to exceed storage beyond eight months (unless there are different indications on the” packaging provided by the PCB manufacturer), even if the circuits are vacuum-packed. (Usually, suppliers pack the circuits in airtight packages with Nitrogen).
The various PCB manufacturers we work with suggest that storage should take place in suitable enclosed environments appropriate for the intended use, maintained at an ambient temperature of 20 degrees C +/- 5 degrees C with “maximum relative humidity” (RH) of 70%.
It is important that after 8-10 weeks from the production date (shown on the package and/or on the circuit itself), the boards should always undergo conditioning treatment (Baking).
This treatment allows for the complete elimination of “moisture”“” absorbed “” by the printed circuit board.
Depending on the circuit finish (HAL, Chemical Gold etc.), Prime has established different reconditioning methods. If interested, don’t hesitate to contact our technical office tecnico@primelettronica.com.
Reconditioning is performed using a static oven, preferably with air circulation, stacking the circuits in piles of no more than “10 boards on top of each other”. (MIL-55110)
Be aware that prolonged and uncontrolled oven exposure can “seriously compromise the solderability” of the board and trigger a process of “” premature aging “”.
We hope this information has been useful. Any feedback from you is valuable and appreciated – we would be pleased to receive it at qualita@primelettronica.com.
