# Why do letters on a PCB not match those on the back side?

This is a typical PCB from ebay, front and back side:

The sides are identical, and not mirrored. Which is funny because the A row on the front is the X row on the back.

Is there a logical/practical reason to this, or is it just convenient for the manufacturer to print only one layout instead of mirroring the letters on the other side? I would find it much more useful if the letters were mirrored and could be used to uniquely identify a hole, no matter which side I am looking at the PCB from.

• I would say it is not a question to manufacturer, but rather to PCB designer - the person or entity producing Gerber files. I agree with @Trevor you need to ensure that flipping board around the same edge you see A on pad at one side and X on the same pad on another side, it is not clear from your picture (and from your explanation). – Anonymous Apr 22 '17 at 9:18
• The manufacturer hired an inexperienced PCB designer who did not pay attention to this detail. – coderworks Apr 22 '17 at 16:02
• Can you show the whole board btw. – Trevor_G Apr 22 '17 at 16:04

You got what you paid for. Rock bottom quality at rock bottom prices. It's typical of cost cutting manufacturing.

• In what way does producing a PCB in this manner "cut costs"? Is it that much cheaper to duplicate the print on the reverse of each unit rather than having a second, pseudo-mirrored print? – Lightness Races in Orbit Apr 22 '17 at 12:16
• @BoundaryImposition I presume it would be, tooling is one of the larger costs of PCB manufacture - one set of silk screen stencils. Probably even only one set of masks for copper, solder mask and silkscreen. Use the same masks for top and bottom sides. – Tom Carpenter Apr 22 '17 at 12:59
• @TomCarpenter: I see! – Lightness Races in Orbit Apr 22 '17 at 13:05

There's no logic, practical or convenient reason for this. If what you write is true, it is not a typical PCB. It's a flawed PCB; someone made a mistake.

• Or just stereotypical Chinese engineering. – Ignacio Vazquez-Abrams Apr 22 '17 at 6:13
• It is in fact from China. (Updated my question.) – Simon A. Eugster Apr 22 '17 at 6:38
• @SimonA.Eugster It doesn't have to be from China to have a mistake. I once swapped the letters next to a pin header on a board I made. However, I never tried to sell them.. – pipe Apr 22 '17 at 14:08

Which side is the "FRONT" ?

Arguably it does not have a front till you put something on it... at which point the labels on the back become meaningless.

Still not too handy though.

• Not really. Put item a in hole a1 and a3. Now solder a1 and a3 on the back. Item a falls out. Instructions unclear. Because of the mismatched labels. – Passerby Apr 22 '17 at 15:43
• @Passerby, yes I understand, and agree with you. But figured it was worth a mention. – Trevor_G Apr 22 '17 at 16:05