How to connect the top and bottom copper in double sided pcb?

[hamid159]

i'm making 4 bit multiplier.which is too much complicated that it cannot be made on one sided pcb so i have to make it on double sided pcb.i'm facing the problem in connecting the top and bottom copper.Please can anyone tell me what is the easiest way to connect the top and bottom copper in double sided pcb?

 

[Mattylad]

Use plated through holes.

Or are you referring to a home made PCB?

In which case this is often done with making vias top/bottom that a left over/cropped resistor lead etc can be fed into and soldered both sides.
Or using through hole components instead of SMT where you can.

 

[hamid159]

there are so much holes i cannot use resistor leads....please any easy method???

 

[wizpic]

unless you get the PCB made at a fab house then there is no easy way to do it really all home made ways are time consuming , other than what is stated, What I have done in the past is when I laid out the PCB where you have got a cap/ic is placed a pad at the side of it so you can solder both sides to make sure the connection is made. This is one way but expensive

 

[alexan_e]

there are so much holes i cannot use resistor leads....please any easy method???

How big is your circuit, how many components does it have?

 

[hamid159]

consists of 16 chips (14 pins),8 leds , and 8 resistors

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This is my ares diagram.......

 

[alexan_e]

Autorouting is not the best option.
I'm sure you can reduce the vias if you move the chips and/or use different gates, for example in chips that have six same gates it makes a difference which one you use to connect to another because each one is in different pins and some of them may be routed easier.

You can also try to reduce the track size (assuming you can manufacture the board) and the chip pad size in order to fit more tracks between two pins (probably two that don't cross)

 

[FvM]

there are so much holes i cannot use resistor leads

Only the vias (I guess 150 or so) need to be through connected by wire pieces, looks still feasible. Some vias might be removed by track optmization, as already said.

The more serious problem, this won't work without sufficient large via pads. Your smallest drill tool might be 0.8 or 1 mm, so you'll need e.g. 1.6 mm via pads.

Another point, I don't see any bypass capacitors near the logic ICs. Good design practice would suggest one capacitor per DIL IC.

A more comvenient solution would be a programmable logic device replacing the large number of DIL logic ICs.

 

[hamid159]

Hy FvM,you are right that i should use programmable logic device but it is my university project..i'm restricted to do it by DIL logic ICs
i have also searched a little bit on google..there is another method i.e, silver gel through hole processing....Please tell me is this method easy and reliable????

 

[FvM]

silver gel through hole processing....Please tell me is this method easy and reliable????

Neither easy nor reliable without the right materials and tools, I fear.

Using wire for via throughconnect is straightforward and easy. Alternatively there are special rivets or pins. You are planning to assemble a single board? Don't make a thing of it.

 

[marce]

Firstly a schematic would help.
Secondly and most important, where are your power tracks?
Thirdly, for a design like this you need to employ true X Y routing, there are places where a track goes the wrong way and you have to jump it with another using two vias.
Often doing any layout you will try different placements to optimise the routing, this is one of the main skills to develop for good PCB design; Placement.

 

[hamid159]

Only one board i have to make....i've also tried different placements as marce said but jumper reduces to maximum 90...there are about 100 holes i have to place leads......

 

[alexan_e]

there are about 100 holes i have to place leads......

I'm sure you can optimize it even more but at this point I doubt it's worth the time you'll waste for a one time board, you have probably wasted more time in this thread than the time needed to solder 100 wires :roll:

 

[FvM]

there are about 100 holes i have to place leads......

Sounds like a normal procedure.

As already said, you'll primarly need sufficient large via pads that can be drilled and soldered regularly.
For the placing of through-connect wires, you can e.g. flatten the wire ends with a suitable tool so they don't fall out of the holes before soldering. Or use something like Harwin track pins:

 

[ZASto]

https://zastos.com/wp/plocice-rutiranje-i-ostalo/
You have two flags for two different languages. Details of a proto that I made years ago. All side changes are made on component pins. Not a single via.

 

[hamid159]

alexan_e.....i know i have wasted more time in this thread but it will increase my knowledge.if sometime i will have to make such type of pcb,it will be easy for me to make it ;-)