Need help with PCB traces

Thread Starter

RB Pyro

Joined Dec 20, 2020
9
I'm very new to this to start so forgive the ignorance, I'm needing to connect 2 DB25 connections on a pcb in a serial pattern. I have tried arranging the connectors a few different ways but I can never get pin 1 to trace to pin 1 on the other connector without the trace blocking of access to the other pins.
 

jpanhalt

Joined Jan 18, 2008
10,963
Welcome to AAC, RB.

I'm very new to this to start so forgive the ignorance, I'm needing to connect 2 DB25 connections on a pcb in a serial pattern. I have tried arranging the connectors a few different ways but I can never get pin 1 to trace to pin 1 on the other connector without the trace blocking of access to the other pins.
Mapping pin1(connector0) to pin1(connector1) sounds like you are putting them in parallel, which is what I suppose you mean. Let me work on it a few minutes and will edit. Using a double-sided board is an easy way to get it done. Is it safe to assume you are committed to a single-sided board, and the connectors are side by side on the edge?
 

Thread Starter

RB Pyro

Joined Dec 20, 2020
9
Yes in parallel sorry! And its at least a 2 layer board. Its for a fireworks firing system i built. 1 through 20 pins are 1 = cue 1 2= cue 2 etc. positive side. 21 through 25 are negative leads going to a rotary switch. But the db25 to db25 needs to be connected because they act as a pass through to feed the next pcb that would be the same thing.
 
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jpanhalt

Joined Jan 18, 2008
10,963
I couldn't find a DB25 connector in Eagle easily. It's probably there, but there are 100's to sort through. Assuming the set up is side by side, not stacked like cookies, then something like this works with a double-sided board:

1608468622058.png

The "dots" are where the trace goes from top to bottom. The connector is through hole, so top or bottom for each pin doesn't matter. Of course, in the DB25, the two rows of pins are staggered. If you can't fit a trace between them, then just swap the connection s from left-side to right-side.

EDIT: Of course, if you stack them or flip one connector, it is easier. I assumed you wanted them to have identical orientations.
 
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Thread Starter

RB Pyro

Joined Dec 20, 2020
9
Ok I get that now. How would I connect the tip layer to the bottom layer? Or what would that look like on pcb design software at least?
 

jpanhalt

Joined Jan 18, 2008
10,963
On a double-sided board, top and bottom layers are connected with "vias," which are a type of plated through hole. Your through-hole pads are on both sides of the board and are connected to each other by a plated "tube." They are called PTH (plated-through holes).

I will need to know the part number for the connector you are using to show what a board looks like.
 

jpanhalt

Joined Jan 18, 2008
10,963
That's a surface mounted device. From a routing standpoint, it makes little difference. From a robustness standpoint, I would recommend a TH device. Surface-mounted connectors can be more easily dislodged, which ruins the board.

Sorry, was looking at the drawing wrong. Didn't realize it was right angle..
 

Thread Starter

RB Pyro

Joined Dec 20, 2020
9
Would something like this work? In my mind it makes sense, I would just need to label one side input and the other output.20201220_103042.jpg
 

jpanhalt

Joined Jan 18, 2008
10,963
Mirroring puts the connector on the bottom. If they are both on the bottom, the geometry is not changed. Like I said, they can be stacked like cookies (or lined up like dominos) on either side of the board.
 

jpanhalt

Joined Jan 18, 2008
10,963
Here are 2 versions:
1608478949040.png1608479033969.png

Red is to trace; blue is bottom. The green circles are plated-through holes/vias. I substituted a 20-pin connector of similar geometry. No time to draw the 25-pin connector that I am unlikely ever to use.
 

jpanhalt

Joined Jan 18, 2008
10,963
Of course, but you have given very little indication of how you want the board designed. I assumed same edge facing same direction You did not correct that assumption. I am tired of making guesses. Design your board and post images in this thread if you want comments about it.

Edit: I should also add that for a single-sided board, you can loop around one connector and avoid crossing traces, but that gives an unnecessarily long trace if you have a double-sided board.
 
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MaxHeadRoom

Joined Jul 18, 2013
22,036
I'm very new to this to start so forgive the ignorance, I'm needing to connect 2 DB25 connections on a pcb in a serial pattern. I have tried arranging the connectors a few different ways but I can never get pin 1 to trace to pin 1 on the other connector without the trace blocking of access to the other pins.
Normally the DB25 etc connectors are used on the outside of equipment for different device connections etc.
If this is just inter-board connections that are permanently connected, why not use something like IDC etc ?, also in this way ribbon connection could be made if convenient.
DB25/DB9 are seldom used on the PCB itself.
Max.
 
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