Dk
Dk turns up in 2 fields: PCBs, textiles. Here is what it means to the people in each one.
Dk in PCBs
Dielectric constant: how much a board material slows signals and sets trace impedance, relative to vacuum.
Dk, the dielectric constant or relative permittivity, describes how strongly a laminate stores electric field energy compared with vacuum. It sets signal speed, roughly the speed of light divided by the square root of Dk, and is a key input to trace impedance. FR-4 runs about 3.8 to 4.6 and shifts with frequency, resin content and glass style, while RF laminates hold values such as 3.0 or 3.5 tightly. Its partner Df, the dissipation factor or loss tangent, sets how much signal turns into heat.
"Fab says the effective Dk of that 1080 prepreg is closer to 3.7, rerun the impedance calc before we lock the stackup."
DK in textiles
An abbreviation for double knitting, a medium yarn weight widely used for garments.
DK stands for double knitting, a standardized yarn weight that is heavier than sport weight but lighter than worsted. It typically knits up at a gauge of 21 to 24 stitches per four inches on US 5 or 6 needles. Spinners and dyers label yarn as DK to help knitters match patterns designed for mid-weight sweaters, baby clothes, and winter accessories.
"Substitute any DK weight merino you have in your stash if you want to hit the right gauge for the cardigan."