Part Number:TIDA-01573
Dear Sir/Madam,
We are currently working designing a LiDAR system, for this we want to use the reference design of the TIDA-01573. We want to integrate the design in our own system, therefore we are considering to redesign it a bit. We however have a limit budget, therefore it is actually not an option to use the blind micro vias. In the reference design focus has been put on the fact that microvias are necessary to limit the parasitic inductances, keep the return current loop as small as possible and to improve the vertical current extraction from components. I must note that we do not have much experience with high frequency design, our current idea is the following; since the the wavelength of the signal, 0.3 m when considering a 1ns pulse, is more than 10x greater when compared to the thickness of the PCB, which is 1.6mm the stub created by an all through via should not influence the performance. Therefore it must be possible to use an all through via with a drill diameter of 1.5mm, or are we not considering other effects, if so could you enlighten this?
Next we were also wondering whether it is possible to place these all through vias not directly on the pad of the EPC2019 and the LMG1020 but as close as possible to the pads. Since placing the via on the pad could lead to the solder paste getting sucked in the via capillarily, leaving too little to solder the part's connection. Of course placing the via's of the pads would mean that the EPC2019 would have one less via, in its 4th pad which is connected to the PWRGND and the area surrounding the EPC2019 would also be changed a bit. We believe that changing this would only add some extra inductance, but have not been able to determine how much and whether other effects are at play. Therefore we hoping you could give us more insight into your desicion of using blind microvias instead of the less costly standard all-through vias?
Laslty we were considering the impact of increasing the hole drill diameter from 0.15 to 0.2mm, increasing this would also influence the layout and the via would not be able to fit on the pads of the EPC2019 and LMG1020. But if not placing the vias on the pad has limited influence, maybe increasing the diameter size would also not greatly influence the design.
As you might tell we have little experience and are wondering whether we are making the wrong assumptions, therefore we really hope that you could help us by giving an explanation of how much our current idea of using all-through vias placed on or off the pads would negatively influence the performance of the TIDA-01573?
Thanks in advance, we hope to hear from you soon.
With kind regards,
Eva