Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water may be also soaked by capillary forces through voids in the materials and along the reinforcement. Epoxies of the FR-4 materials aren't too susceptible, with absorption of only 0.15%. Teflon has very low absorption of 0.01%. Polyimides and cyanate esters, on the other side, suffer from high water absorption. Absorbed water can lead to significant degradation of key parameters; it impairs tracking resistance, breakdown voltage, and dielectric parameters. Relative dielectric constant of water is about 73, compared to about 4 for common circuitboard materials. Absorbed moisture can also vaporize on heating and cause cracking and delamination, the same effect responsible for "popcorning" damage on wet packaging of electronic parts. Careful baking of the substrates may be required.
If materials absorb moisture and then are heated enough to vaporize the water, the board might show delamination or what other type of damage?
cracking

In 2011 the National Archives initiated a Wikiproject on the English Wikipedia to expand collaboration in making its holdings widely available through Wikimedia.
In 2011, what sort of Wikipedia addition did the National Archives make?
Wikiproject

The Most Excellent Order of the British Empire is the "order of chivalry of British constitutional monarchy", rewarding contributions to the arts and sciences, work with charitable and welfare organisations and public service outside the Civil Service. It was established on 4 June 1917 by King George V, and comprises five classes, in civil and military divisions, the most senior two of which make the recipient either a knight if male, or dame if female. There is also the related British Empire Medal, whose recipients are affiliated with, but not members of, the order.
Who is the recipient?
knight if male, or dame if female