Disclosed are biaxially oriented polyester film produced from a polyester
comprising: (1) diacid residues comprising at least 90 mole percent of
terephthalic acid residues, naphthalenedicarboylic acid residues or
combinations thereof; and (2) diol residues comprising at least 90 mole
percent of 1,4-cyclohexanedimethanol residues; wherein the polyester
comprises a total of 100 mole percent diacid residues and a total of 100
mole percent diol residues; wherein the polyester film is stretched at a
ratio of about 2.5.times. to 3.times. in the machine direction (MD) and
about 2.5.times. to 3.times. in the transverse direction (TD) at
stretching temperatures between 90 and 1 10OC, wherein the stretched film
is subsequently heat-set at an actual film temperature of from
260.degree. C. to Tm, wherein Tm is the melting point of the polyester as
measured by differential scanning calorimetry (DSC), while maintaining
the dimensions of the stretched film, and wherein the biaxially oriented
and heat-set polyester film undergoes not more than 3% shrinkage when
immersed for 10 seconds in a solder bath preheated to 260.degree. C. and
exhibits a coefficient of thermal expansion value of 10 85 ppm/.degree.
C. when measured between 120 and 150.degree. C., and a coefficient of
thermal expansion value of 10 42 ppm/.degree. C. when measured between 25
and 90.degree. C.