First time ordering a PCB ... what do all the options mean?!

Discussion in 'The Projects Forum' started by EnjoyIce, Apr 9, 2016.

  1. EnjoyIce

    Thread Starter New Member

    Jan 13, 2014
    25
    0
    Hey guys (another post by me!)

    I am about to order a PCB for a project and I have never done this before. There are loads of different things to choose from and the 'handy help' buttons don't really give any handy help at all to what the differences actually are.

    In terms of board layers .. is there any benefit to having more than one? The circuit I need is simple (its just an led array). Would having more layers help with thermal issues?

    Base material: FR4 Tg 130 / FR4 H Tg 170 - FR4 is a composite fibreglass material and I assume the 130/170 is the thickness? No idea what the H stands for!

    Does the copper weight matter at all?

    Solder mask: that is the (usually) green cover on the PCB that protects the PCB? I assume its best to have it on top and bottom for protection.

    Silk screen: is the 'map' of where everything connects and goes? So I should definitely have that, probably just on the top.

    Surface: There are lots of options here .. HASL from what I can see is being dipped in solder and then using hot air to cut away the unneeded solder. There are two HASL options ('not RoHS' and 'lead free'). Another option is Electrolytic Gold which is probably more expensive so I'll ignore that. OSP is an organic process but doesn't last too long. Immersion gold is also expensive. Immersion silver is also an option that looks like it may be ok.

    Would HASL be the best one to go for?

    I just need a PCB on which I can connect my LEDs and an Arduino, so it doesn't need to be really fancy or anything. Just as long as it works! (And isn't too expensive)

    Also - do you recommend any easy to use software to create the PCB schematics? There are loads of free packages out there so its more a case of if you'd recommend any specific one over the others?

    Thanks!
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    I just received a shipment from DirtyPCB.com $25/10pcs 10cm x 10cm in HASL.
    I have settled on free Kicad for schematic capture etc, I find it just as good, if not better than the old Orcad system I had and had to abandon because of later version of Windows.
    Anything other than HASL is usually added cost per feature.
    Max.
     
    Last edited: Apr 9, 2016
  3. SLK001

    Well-Known Member

    Nov 29, 2011
    817
    227
    In terms of board layers .. is there any benefit to having more than one? The circuit I need is simple (its just an led array). Would having more layers help with thermal issues?

    Thermal issues are not usually solved by more layers.

    Base material: FR4 Tg 130 / FR4 H Tg 170 - FR4 is a composite fibreglass material and I assume the 130/170 is the thickness? No idea what the H stands for!

    I imagine that the "H" stands for hi temp. Tg is the symbol for "glass transistion" temperature. For a general purpose PCB, select the Tg 130.

    Does the copper weight matter at all?

    Depends on your circuitry. Are there a lot of high current carrying traces? If not, then 1 oz copper is usually sufficient.

    Solder mask: that is the (usually) green cover on the PCB that protects the PCB? I assume its best to have it on top and bottom for protection.

    Solder mask is just that. It masks where the solder should NOT go. If you have a thru-hole construction, use mask on both sides.

    Silk screen: is the 'map' of where everything connects and goes? So I should definitely have that, probably just on the top.

    Do you have anything on the bottom? Then screen it. You can use the bottom silk to add info to aid YOU.

    Surface: There are lots of options here .. HASL from what I can see is being dipped in solder and then using hot air to cut away the unneeded solder. There are two HASL options ('not RoHS' and 'lead free'). Another option is Electrolytic Gold which is probably more expensive so I'll ignore that. OSP is an organic process but doesn't last too long. Immersion gold is also expensive. Immersion silver is also an option that looks like it may be ok.

    HASL stands for Hot Air Solder Leveling. This means that the board is run thru solder then a hot air knife blows the excess off the board. For a GP PCB, HASL is nice to have. It is almost like the old tin plating.

    Would HASL be the best one to go for?

    Yes.

    I just need a PCB on which I can connect my LEDs and an Arduino, so it doesn't need to be really fancy or anything. Just as long as it works! (And isn't too expensive)

    Also - do you recommend any easy to use software to create the PCB schematics? There are loads of free packages out there so its more a case of if you'd recommend any specific one over the others?

    I recommend Cadsoft's Eagle package.
     
    ErnieM likes this.
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    The one thing with Eagle it is not free unless you keep to the restrictions of the freeware version.
    • The useable board area is limited to 100 x 80 mm (4 x 3.2 inches).
    • Only two signal layers can be used (Top and Bottom).
    The schematic editor can only create two sheets.
    Max.
     
  5. magnet18

    Senior Member

    Dec 22, 2010
    1,232
    124
    What board house are you looking at going through?
    Have you looked at http://**********.com/ ?

    I also recommend KiCad, eagles free package has a board size limitation (not usually an issue for hobbyists though)
    I like that it's open source, no constraints, pretty easy to get the hang of, and does a very good job.

    Also, you will probably find that 2 layers is the minimum, and I don't see how you could do an LED array with less than that anyway.

    EDIT
    why is p c b s h o p p e r . c o m censored out???
     
  6. EnjoyIce

    Thread Starter New Member

    Jan 13, 2014
    25
    0
    I was originally looking at sites that were charging £100/£200ish so was quite a suprise when I looked at dirtypcbs and its nowhere near that.

    I need 84*127mm (85*125 roughly) so I can't use the free eagle software sadly! (I'll have a look at kicad)

    I just had a look at ********** actually - found smart-prototyping which seems to be similar to dirtypcbs. Both relatively cheap from china. Quality isn't too important for now as this is just creating a prototype to see if it all works nicely. Delivery time is probably the most important!

    Prices seem to sky rocket with faster delivery though sadly :(

    Also thanks for clearing up what all the different options mean - its nice to know what I am paying for!
     
Loading...