Questions tagged [via]

In a PCB, a via is a plated hole that allows electric connection between layers. This is the more common use of the term on this site. In integrated circuit, a via is a small opening in an insulating oxide layer that allows a conductive connection between different layers.

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17
votes
2answers
12k views

How are vias made commercially?

How are or were vias made commercially? Wikipedia (http://en.wikipedia.org/wiki/Via_(electronics)) mentions "The hole is made conductive by electroplating, or is lined with a tube or a rivet" Can ...
2
votes
1answer
257 views

Correcting printed PCB (add a via)

This board is a prototype for the project and is for testing. It is missing the soldermask and silkscreen layers, so correcting mistakes is very possible. The board was printed correctly, but somehow ...
8
votes
1answer
328 views

Compensating for unbalanced via count in DDR3 routing

I'm working on a DDR3 layout at 533Mhz clock speed in a balanced T configuration. I am currently unable to route the address/ctrl lines with an equal amount of vias (+1 on a limited number of lines). ...
1
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1answer
1k views

Calculating Signal Loss (dB) Through Vias

Does anyone have any useful calculations or links to material covering good ways to calculate signal loss through vias? What would be perfect is a graph with typical loss in dB over the range 1GHz ...
3
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2answers
1k views

Via through TQNF Exposed Pad

Is it ok to use an "ordinary" via to connect the Exposed Pad of an TQNF package to ground, as shown in the following picture? I am using eagle. DRC generates an "overlap" error, is it ok to ignore ...
3
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3answers
282 views

What tool can make a nice 3D image of a via?

I found this graphic somewhere on the web, but now I need to create a similar illustration for some training, but with a 16 layer board having traces coming in on other layers etc. What is the ...
13
votes
1answer
3k views

Why does reflection off a PCB via look like this?

My question is related to http://mobius-semiconductor.com/whitepapers/ISSCC_2003_SerialBackplaneTXVRs.pdf. On the page 18 there are a few figures of "TDR off Diferent Types off Vias". I am confused ...
10
votes
1answer
481 views

Purpose of exposed ground pads

I have a Beckhoff EL2008 8-channel digital output terminal that I took apart because I'm using an ASIC that is inside the module, Beckhoff's ET1200. There is essentially a ring of ground pads,some ...
14
votes
1answer
2k views

Using a via to strengthen surface mount connector on or near pad

I am trying to design a board that has a surface mount connector. I was shown a picture of an example board that has vias on the pads of the connector. I don't believe the via is for connecting to a ...
6
votes
1answer
835 views

Additional signal plane vs lots of vias

I have a circuit that I am currently designing using a 4 layer PCB (signal, ground, power, signal). The PCB has rather a lot of vias to route the signals around the board (there are size constraints, ...
3
votes
1answer
633 views

Vias in a footprint using Eagle

I have a fairly complex footprint which I have created in Eagle. Particularly the complexity comes from the number of vias required for the footprint (this is an RF part). Initially I tried to drop ...
1
vote
3answers
243 views

Double side PCB with solder via?

Normally vias are made with through hole plating. In the past they used to make vias by soldering a piece of wire to connect the top and bottom layers (like a short piece of 24 gauge copper wire). ...
2
votes
3answers
390 views

Do I need to use thermals on vias for reliability?

This question is further to Why thermal reliefs on vias? I have recently been advised (by someone I consider an expert) that I should add thermal reliefs to vias which are connected to planes, even ...
6
votes
3answers
2k views

Altium: Query to target Vias in Pads

Does anyone have a Altium query/selector that targets vias in SMT pads? I'm routing a very dense HDI board, and would like to make rules that exclusively target vias that are inside a component pad ...
4
votes
3answers
10k views

Altium Thermal Pad shortcircuit

All my QFN footprints are made with the Altium internal "Tools -> IPC Compliant Footprint Wizard". I get nice footprints with vias in the thermal pad. When I try to place one of those footprints to ...
4
votes
3answers
3k views

Ground vias on high speed PCBs

I know that if I use vias on high speed traces that I need to reduce the inductance effect of the via. So I will put ground vias next to these vias to help returning current. I have seen a picture ...
5
votes
3answers
4k views

PCB vias impact in cost

Often times I read comments/recommendations about placing lots of vias for GND in 4-layer designs, as well as a line-up of vias surrounding the board to protect from EMI, etc. I was always under the ...
4
votes
1answer
3k views

Eagle via diameter discrepancy

I made a part in eagle with vias using a set diameter (smaller then auto), but when I use the part on a board, the vias go back to having a diameter of auto. any ideas? The left window shows the ...
6
votes
3answers
5k views

SOT-223 Thermal Pad and Vias

I am using a LDO with a SOT-223 footprint and since it might get hot, I wanted to make a nice thermal pad under it to dissipate that heat. I googled and I only found thermal pads, but i wanted some ...
11
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1answer
11k views

How to connect ground planes together

What is the best way to connect ground planes together ? I know that ground planes are connected together at multiple locations in order to keep a low impedance GND across the whole board and provide ...
30
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5answers
11k views

Testpoints: Vias versus pads

I was fixing an ultra cheap home router few days ago and noticed that it had vias marked TP_12V, TP_3V3, TP_GND and similar. The problem turned out to be leaky electrolytic crapacitors in the buck ...
20
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2answers
15k views

Castellated/Edge-plated PCBs: Comments on Mechanical/Electrical contact reliability

(This is a follow-up to this related question). I'm interested in some feedback from people's design results/experiences with Castellated PCBs as a method of attaching one PCB to another. By ...
27
votes
7answers
29k views

vias directly on SMD pads?

I was looking at an example board schematic provided by TI and I noticed something rather curious: vias were placed directly on SMD pads. Is this a normal/acceptable practice to follow? Or is it ...
11
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1answer
5k views

A few questions about vias and pads on a PCB

I have been used to work with 1 layer PCB's and prototype boards. On the bottom layer are all the routes and the soldering , on the "top" layer are only the components. Now, I am trying to work with ...
3
votes
1answer
1k views

Reducing cost by eliminating microvias when designing a PCB with buried vias

I'm designing a 4-layer PCB for a very small adapter from a BGA on one side to several discrete SMT connectors on the other. Due to space constraints, I cannot use through holes for some of the ...
18
votes
2answers
5k views

Should you place traces at right angles through a via?

I understand that right angle pcb traces should be avoided because it can cause problems during manufacturing. But what about right angle through a via? Will this have any negative effects? I ...
20
votes
2answers
3k views

Can you place vias inside a QFN footprint?

I am designing a very dense PCB containing a 0.4mm pitch QFN chip. In parts it is proving very difficult to fan out. It is made all the more difficult by the huge thermal pad that all QFNs have for ...
7
votes
1answer
5k views

How to calculate signal propagation speed through vias?

There is a need to have a group of signals arrive simultaneously to their respective destinations, given that they start their journey at the same time. However, due to physical constraints it is not ...
2
votes
3answers
191 views

My Vias are getting shorted on the back of my chip

I have a board design using a Atmel AT90USB1286 (VQFN64) and I placed vias on the back of the chip for routing purposes. Upon inspection, I found that the AT90USB1286 Chip has a thermal pad on the ...
10
votes
4answers
24k views

Changing all via and routing sizes at once (Altium Designer, PCB Design)

I have a completed PCB design drawn by Altium Designer. I want to increase via sizes. But there are too much of them, and changing all of them one by one will be a very long and bothersome work. Is ...
3
votes
2answers
448 views

Designing PCB - is this design OK?

No, I'm not asking you about my whole design - just one little bit of it. I have SMT devices, and I am currently pushing 8 pins on each side of some chips (SO24) straight through to the other side of ...
15
votes
3answers
10k views

BGA escape via dimensions at 0.8mm pitch?

Are there any kinds of standards or common practice dimensions which define what BGA escape vias and routing trace/space should look like at 0.8mm pitch? If not, what's the most economical set of ...
6
votes
3answers
3k views

Is it important that vias are plated on a PCB?

As in the title. I've noticed several PCBs of mine have vias which are not plated - they do not have a characteristic "gold" shine to them. I suspect this is because I was pushing the limits of drill ...
20
votes
6answers
81k views

Standard via sizes?

Is there a standard for via sizes, or can you make them any size you want? (I'm going to be using traditional PCB houses to manufacture my PCB's.)