Molded Interconnect Substrate (MIS) Technology for Semiconductor Packages

Liu, Michael M.

doi:10.1109/ectc32862.2020.00067

Cited by 2 publications

(2 citation statements)

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“…This is associated to the different thermal properties and especially heat dissipation of both materials. Whereas copper provides a high thermal conductivity between 377-385 W/mK [54,55] and is thus capable to dissipate the occurring heat at higher laser burst repetition rates into the surrounding material, the multi-component ABF substrates are assigned to have low values between 0.5-2.5W/mK [56]. Therefore, we assume that strong heat accumulation already occurs at a laser pulse repetition rate of f B = 10 kHz for processing ABF material.…”

Section: Ablation Thresholdmentioning

confidence: 99%

“…If an intra-burst pulse is absorbed by the insulating ABF substrate, a certain amount of the absorbed laser fluence below the ablation threshold is converted to heat in the material [58]. In turn, due to the low thermal conductivity of ABF substrate of <2.5 W/mK [56], the induced heat can not dissipate into the surrounding material within the time scale of successive intra-burst pulses of Δt BP = 12 ns. Therefore, in laser microvia percussion drilling, heat accumulates as the number of laser bursts and intra-burst laser pulses increases, producing a smaller taper value.…”

Section: Evaluation Of the Microvia Drilling Quality 321 Taper Diamet...mentioning

confidence: 99%

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Picosecond laser microvia drilling of ABF material using MHz burst mode

Franz,

Häfner,

Bischoff

et al. 2023

Mater. Res. Express

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We report on a comprehensive study of laser percussion microvia drilling of Ajinomoto build-up film (ABF) material using an ultrashort pulsed laser in MHz burst mode. After laser processing, microvia drilling quality is being evaluated by the fabricated diameter and taper using laser scanning microscopy and metallography. The influences of the incubation effect, heat accumulation and shielding effects as a result of pulse to pulse interactions are being discussed on the ablation threshold, penetration depth and laser microvia drilling quality. We find that an increasing heat accumulation in MHz burst mode processing is responsible for the void formation and delamination of the insulating ABF layer. Therefore, the parameter clearance is introduced to evaluate these effects on the microvia sidewalls. For a comparable clearance, applying 2 intra-burst pulses achieves an average reduced taper of down to 19.5% compared to single pulse mode. At the same time, a reduced laser drilling time of 16.7% per microvia highlights the enormous potential of the MHz burst mode for laser drilling of ABF material in printed circuit board fabrication.

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Section: Ablation Thresholdmentioning

confidence: 99%

Section: Evaluation Of the Microvia Drilling Quality 321 Taper Diamet...mentioning

confidence: 99%