Standard for size of plated through holes?

You need to talk to your board house about minimum plated hole sizes. We commonly use 0.010" dia via sizes, sometimes down to 0.008" dia.

If you're thinking about hole size for through-hole component leads, the one of the IPC standards may have the proper info.

What Standard defines the size of plated through holes in a PCB? Thanks

Depends on the board supplier. I use PCB-Pool a lot for prototypes and their minimum size is 0.3 mm for double-sided and four-layer boards.

Leon

ANSI/IPC-2222, "Sectional Design Standard for Rigid Organic Printed Boards" Table 9-3

From a practical point of view, anything from 25% to 50% larger than the component lead will solder nicely. If you go much smaller, you will rip out the plated holes when you try to rework the board. Much larger, and you will have trouble filling the holes with solder.

-Chuck

Thanks. But dunno which one. I should have made it clear that I'm interested in plated through holes for components, so obviously they must be a minimum size for the purposes of solderability

I use .035" for most component leads - ICs, 1/4W resistors, etc. The ..025" square post headers need .040.

Holes should normally be about .010 or so larger than the component lead.

I use .025" for via holes - at one point the board shop charged extra for .024 or less, so that set my via size.

--
Peter Bennett VE7CEI 
email: peterbb4 (at) interchange.ubc.ca        

interested

minimum

Consider a PCB in front of you, like a old motherboard with a intel 286. Desolder an IC without damage. The hole size will be about 0.030"

+/- 0.005 ? The IC pins will be about 0.020". Take a brand new DIP IC and measure the pins with some calipers. Add 0.010" to the pin size. That's you drill hole size. That's your standard.

As to any standard? I havn't bothered to look around. The last standard I used was IPC-610. It's all changed now.

Find out who sells PCB drills. Look at the Drills sizes being used by the CNC machine.

etc,

What I learned is make all the holes on the PCB 0.030 or 0.040" Why? Because, imagine if you will. You layout your board and use the defaults from the CAD your using. Unknowingly, the drill file makes 10 different drill size call outs. The Gerber drill files will tell you at a glance, what's with all these Gerber drill files?

Imagine, a guy standing infront of a CNC drilling machine. You called out for a 0.008" drill hole. The guy has probably 100's of different drills sizes, in thousandths of an inch and millimeter sizes. The drill guy has to find a drill that small. If he dosen't have it, then he has to order it... It Takes Time. Your time in the end.

Also small drill bits break. What happens if the drill breaks while drilling out your board, or someone elses board? Production stops till the drill gets changed out. Damage acessment by the Board House QC as to damage accessment to your stack of boards he's drilled out so far. Now... do we have to cut more blank boards because the drill broke in the middle of the board stack, the booklet? Yes or No? etc. What's a booklet? Your PCBs start by cutting 3 blank copper boards, stacking them together, pinning them together so they don't move during the drilling process. These 3 blank boards are a booklet.

Drill guy has to change the drill bits, because you called out for so many different holes. That means stopping the CNC drill machine, changing the drill bit, load the new Gerber drill file and start drilling. It Takes Time. And then what happens if another drill bit breaks in the middle a job? Well, you have to start all over from scratch. Happens all the time, all day long.

Question, what will you gain if the via is 0.030" or 0.008" ? I've never seen a difference. Once the board is soldered, who cares? The wave solder will fill in all the holes. If mfg. is by hand, so you have non soldered vias, so what. If you can replace 5 drill hole sizes with a

0.015" drill size, that would be good. If you could replace all drill sizes with 0.030" that would be great. Imagine again the CNC machine, the guy who has to chuck the drill bit, load the CNC file for that Gerber drill size, stop the CNC machine every time to chuck the next drill size, do this tillyou board is done. What happens if all the holes are one size? The drill guy sets up that one drill bit size and the board is done. The drilled out board goes to QC for inspection under a microscope and measure a few hole locations, to match up with the artwork. Tell me you havn't seen a board where the holes were off a bit, the trace makes it to the DIP part or via, but it's off a bit, board ohms out ok, ship it.

1. Design a PCB.

1. Create as fewer Gerber files as possible
2. Send to boards house as a few a Gerber files as possible.
3. Get PCBs made faster.

cya Ed

Ed, did you have to write a book to explain what could have been said in one paragraph? Besides which your details are pretty sketchy. You sound kind of like the guy that stayed at a Holiday Inn Express last night. Volume does not equal quality. In your case a lot less volume would have been more accurate and correct.

(i.e. IPC-610C is an acceptability standard and has nothing whatsoever to do with specifying holes sizes. Nobody stops the CNC machine to change each bit size. There is a tool caddy that typically holds a minimum of 8 tools/bits. Greater than eight tools they will partition the file so that there is one pause to enter the next set of up to 8 drill sizes required. It takes seconds to change the bits in the caddy for the second partition. Smaller via sizes gain you routing area, larger vias require larger pads and take more area. But, larger vias can carry more current and plate through better. You use as many Gerber files as necessary for the layer detail of the board (note: nothing to do with drills), no more, no less. The drills are not dealt with via a Gerber file but rather an Excellon or Ascii format drill file.)

--
Sincerely,
Brad Velander