• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Plated thru hole diamter

Status
Not open for further replies.

Mosaic

Well-Known Member
Hi:
For a part that has an actual diameter lead of 1.2mm.
What size should the PTH be? How much tolerance to add?
I was thinking 1.25mm but then would the plating impact on this?
 

DerStrom8

Super Moderator
Most Helpful Member
IPC-2222 covers this.

9.2.2 Plated-Through Holes
The maximum and minimum plated-through hole diameters used to attach component leads or pins to the printed board shall be evaluated in accordance with Table 9-3. Both minimum and maximum leads shall be taken into consideration in evaluating the finished plated-through hole requirements. If the lead is a ribbon lead, the minimum and maximum diagonal of a flat ribbon lead shall be considered. Table 9-3 shows the limits of the plated-through hole.
These limits shall be optimized so that manufacturability is enhanced to provide the most liberal tolerances allowable (see Figure 9-3).
upload_2017-5-2_6-49-38.png
Unless otherwise specified, the hole size shall be the finished plated size after solder coating or final plating and fusing, if required. The hole size shall be specified on the master drawing. Plated-through holes used for functional interfacial connections shall not be used for the mounting of devices which put the plated-through hole in compression. Plated-through holes used for functional interfacial connections shall not be used for the mounting of eyelets, solder terminals, or rivets. Plated-through holes shall be used for all interfacial connections on multilayer boards Type 3 through Type 6 (inclusive). Platings and coatings shall be in accordance with IPC-2221.
upload_2017-5-2_6-52-55.png
 

Pommie

Well-Known Member
Most Helpful Member
Those seem like huge tolerances in today's age. Most boards I've had made seem to be spot on. 0.7mm over is huge - most of the time my holes are less them 1mm and often less than 0.7mm.

Edit, just pointing out that I think that spec has been overtaken by modern methods.

Mike.
 

DerStrom8

Super Moderator
Most Helpful Member
DerStrom8 could you elaborate on what Level A-C are?
From IPC-2221:
1.6.3 Producability Level
When appropriate this standard will provide three design producibility levels of features, tolerances, measurements, assembly, testing of completion or verification of the manufacturing process that reflect progressive increases in sophistication of tooling, materials, or processing and, therefore progressive increases in fabrication cost. These levels are:
Level A General Design Producibility -- Preferred
Level B Moderate Design Producibility -- Standard
Level C High Design Producibility -- Reduced
The producibility levels are not to be intepreted as a design requirement, but a method of communicating the degree of difficulty of a feature between design and fabrication/assembly facilities....
Simply put, Level A is highest possible quality (medical equipment, aerospace, etc) that is more difficult to produce, Level B is moderate quality (consumer products, etc) which is standard producibility, and Level C is the easiest to produce but with lower quality (hobby projects, etc).
 

Mosaic

Well-Known Member
I guess I'll go with 1.3mm holes for 1.2mm leads. I've tried 1.5mm but mechanical integrity is a bit questionable as these are spade terminals.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top