Through Hole
-
Through-hole design skills
Via hole is one of the important components of multi-layer PCB. The cost of drilling is usually 30%-40% of the cost of the PCB board.
To put it simply,each hole in the PCB can be called a via hole. In terms of function, the vias can be divided into two types: one is used as an electrical connection between the layers; the other is used for fixing or positioning the components. In terms of process, the vias generally divided into three types: blind via、buried via and through via.
The blind via is located on the top and bottom surface of the printed circuits board, and have a depth for the connection of the surface circuit to the underlying inner circuit. The depth of the holes usually does not exceed a certain ratio(aperture).
The buried hole is a connection hole located in the inner layer of PCB, which does not extend to the surface of the circuit board. The above two types of holes are located in the inner layer of the circuit board and are made by a through-hole forming process before lamination.
The third type is called a through-hole, and the hole goes through the entire circuit board and can be used to implement internal interconnection or as a mounting hole for the component. Since the through via is easier to implement in the process and lower in cost, it is used in most printed circuit boards.
First, from a design point of view, a via is mainly composed of two parts, one is a drill hole in the middle, and the other is a pad area around the drilling hole. The size of these two parts determines the size of the vias. Obviously, in high-speed, high-density PCB design, the designer always hopes that the via is small, so that more wiring space can be left on the board.In addition, the smaller the via is, the smaller its own parasitic capacitance would be and making it more suitable for high-speed circuits.
However, the reduction in the size of the hole also brings about an increase in cost, and the size of the via hole can not be reduced indefinitely. It is limited by process techniques such as drilling and plating:
The smaller the hole, the longer it takes to drill holes, the easier it is to deviate from the center position; and when the depth of the hole exceeds 12 times the diameter of the hole, there is no guarantee that the hole wall can be uniformly plated with copper.
Second, While parasitic capacitance exists in the through-hole, parasitic inductance also exists. In the design of the high-speed digital circuit, the parasitic inductance of the via hole is often more harmful than the parasitic capacitance. Its parasitic series inductance weakens the contribution of the bypass capacitor and reduces the filtering effect of the entire power system.
Third, in high-speed PCB design, seemingly simple vias often have a large negative effect on the design of the circuit. In order to reduce the adverse effects of the parasitic effects of vias, it is possible to do as much as possible in the design:
1. Consider the cost and signal quality, and choose a reasonable size of the via size. For vias for the power supply or ground wire, consider using larger sizes to reduce impedance.
2. The thin PCB board is beneficial to reduce the two parasitic parameters of the via.
3. The signal traces on the PCB should not be changed as much as possible, that is, try not to use unnecessary vias.
4. Place some grounded vias near the vias of the signal-changing layer to provide the most recent return circuit for the signal. It is even possible to place a large number of surplus grounding holes on the PCB. Of course, you need to be flexible in design. Sometimes we can reduce or even remove pads from certain layers. Especially in the case of very large via density, it may lead to a break in the copper layer to form a partition circuit. To solve such a problem, we can also consider reducing the size of the pad
through holes in the copper layer.
https://waterfallmagazine.com
Hey there I am so grateful I found your website, I really found you by mistake, while I was researching on Google for something else, Anyhow I am here now
and would just like to say many thanks for a remarkable post and a all round
enjoyable blog (I also love the theme/design), I don’t have time
to look over it all at the minute but I have book-marked it and also added in your RSS feeds, so when I have time I
will be back to read a great deal more, Please do keep
up the excellent job.
I think the admin of this site is really working hard for his website, since here every information is quality based stuff. Arlyne Melvin Wolpert
Retinol SerumCildnizi nemlendirecek ve canlandıracak yüz serumları
Retinol Yüz Serrumu Retinol yüz serumu kullanın.
İşe yarayan cilt bakımı! Konsantre halde eklenen
E Vitamini ve Bitki Bazlı Gliserin, cildin nemlenmesine ve sakinleşmesine
Retinol serum en iyisi retinol Krem Retinol, yaşlanmayı önleyici cilt bakım
rutinlerine dahil edildiğinde,
cilt yenilenmesini hızlandırmaya, kolajen üretimini artırmaya ve yaşlanma,
düzensiz doku ve yaşlılık lekelerinin görünümünü azaltmaya yardımcı olur
Siz de Kuru Saçlar için şampuan
saçlarınız çokmu kuru? o halde neden hemen hc complex denemiyorsunuz?
.
SKincell Pro is popular by the individuals who utilized it as a suitable
skin fixor. The lotion contains the same ingredients as most
of the other moles getting rid of lotions on the marketplace
today, yet it adds more than a number of them. The serum likewise enhances your skin appearance and provides
even-toned skin. The components, the item has are
natural ingredients which are safe for your skin. https://binksites.com/story9267438/how-much-is-a-bottle-of-skincell-pro
I have been surfing online more than 3 hours today, yet I never found any
interesting article like yours. It’s pretty worth enough for
me. Personally, if all site owners and bloggers made good content as you did, the
web will be much more useful than ever before.
You’ve made some good points there. I looked on the internet for additional information about the issue and found most
individuals will go along with your views on this web site.
Thanks, Antalya, are you agree with us?
Thanks, do you have any query for this post?