What is the drill rack?

Archive BatchPCB
1

Hi,

In searching around here I couldn’t seem to find this information here or at the Gold Phoenix web site.

Several questions about drill specs:

  1. What is the drill rack? I presume my sizes will get forced into a few standard sizes used by the batch.

  2. Should the drills be specified as actual drill size or desired finished hole size?

  3. What is the minumum annulus for drills?

  4. What is the minimum mask relief (a.k.a. mask bloom)?

I’ve been rebuilding my footprint library (for gEDA/gaf) so that it can target several different 8/8-capable fabs, so it should work well with batchpcb, assuming the drill requirements are compatible.

2

I’ve always assumed drill sizes are before plating, but the difference is probably around 3 mil, so it usually doesn’t matter to me.

3

Whether drills size is actual drill size or target drill size after plating varies with the fab house. Most of the low-volume prototypers force your specified drill size to a “near by” drill from their default drill rack. I’ve built a footprint library that very carefully selects drill sizes so that I get pretty much what I want from any of three different protyping houses.

4

Olimex charges extra for non-standard drills, and their hole sizes are before plating. Most other suppliers I use simply go by area and accept any number and size of drills, and holes are ‘finished’ size. I prefer the latter.

Leon

5

Any chance we can get back on topic here??? I have very specific questions about detailed specifications. Vague assumptions and reports about what other vendors do are simply not helpful.

Is waiting days for an authoritative answer to a detailed question about how to prepare a board so that it fabs correctly the kind of customer service I can expect here? This is the kind of basic data that should be on line in the first place.

6

I decided to check out some of the boards I’ve received.

All drills get plated.

Hole size you specify is before plating, so the result is around 3 mil smaller.

Some of the measured samples:

Requested, Actual

.072 inch, .068 inch

.130 , .128

.059 , .054

.052 , .049

.126 , .123

.132 , .133

The last one seemed to be a weird exception, but looking at a list of standard drills, the probably used the nearest drill #29 (.136")

c.

#74: .0225"

#73: .024"

#72: .025"

#71: .026"

#70: .028"

#69: .0292"

#68: .031"

#67: .032"

#66: .033"

#65: .035"

#64: .036"

#63: .037"

#62: .038"

#61: .039"

#60: .04"

#59: .041"

#58: .042"

#57: .043"

#56: .0465"

#55: .052"

#54: .055"

#53: .0595"

#52: .0635"

#51: .067"

#50: .07"

#39: .0995"

#38: .1015"

#37: .104"

#36: .1065"

#35: .11"

#34: .111"

#33: .113"

#32: .116"

#31: .12"

1/8: .125"

#30: 0.1287"

#29: 0.1360"

#28: 0.1415"

#27: 0.1440"

#26: 0.1470"

#25: 0.1495"

#24: 0.1520"

7

Hi,

We’re still waiting on a reply from gold phoenix regarding the exact drill sizes they use.

Cheers,

–David Carne

8

They would be using metric drills.

Leon