Patent ID: 8710402

Claim:
A method of using laser pulses to form a blind via in an electronic substrate that includes conductive and dielectric layers, said method comprising: specifying a top diameter and a bottom diameter for said via, wherein said blind via has a depth between said top diameter and said bottom diameter, wherein a ratio of said bottom diameter to said top diameter expressed as a percentage defines a taper of said blind via, and wherein said blind via has a volume corresponding with said top diameter, said bottom diameter, said depth, and said taper; calculating a single set of pulse parameters for said laser pulses based on said top diameter and said bottom diameter, wherein forming said blind via includes a first via formation phase including top via formation circumstances for removing dielectric material above said conductive layer while maintaining said top diameter for said via, wherein forming said blind via includes a second via formation phase including bottom via formation circumstances for removing remaining dielectric material at and above said conductive layer while maintaining said bottom diameter for said via without causing substantial damage to said conductive layer, wherein said top and bottom via formation circumstances are different, wherein said top diameter is related to fluence by the equation D t ≈F, where D t is said top diameter and F is said fluence, wherein said bottom diameter is related to fluence and pulse width by the equation D b ≈F/(t 1/2 ), where D b is said bottom diameter and t is said pulse width, wherein the laser pulses are provided by a laser system having optical and laser capabilities, wherein said single set of pulse parameters is selected to be within the optical and laser capabilities of the laser system, wherein said single set of pulse parameters pulse parameters includes a pulse width and a peak power, and wherein said pulse width and said peak power are selected to minimize an amount of time spent forming said blind via; producing and directing for incidence on said electronic substrate said laser pulses characterized by said single set of pulse parameters pulse parameters employed for both the first via formation phase and the second via formation phase to remove said dielectric layer within said volume to form said blind via without causing substantial damage to said conductive layer material.