PC Board Design Checklist For Through Hole Components

PC Board Design Checklist

For Through Hole Components

This document should be used as a supplement to existing machine General Specifications and IM Design Guidelines.  This document is designed as a checklist rather than a reference for use when examining an existing or new product.  For detailed specifications refer to the appropriate General Specification.

 

PC board considerations

For Axial or Radial auto insertion:

 

Is the overall size of the board within specification?  (max/min size varies by machine and board handling type)

Is the board thickness within specification?

Possible challenges:

Radial can accept boards from 0.032” to 0.093” thick with no set up change, axial machines require mechanical adjustment to handle thickness variations.

If using automatic board handling, is the board shape acceptable?  (i.e. contiguous edges.)

Possible challenges:

Non-contiguous edges, may work but requires testing.  Example, instrument cluster.

Is the board a good candidate for panelization?  (i.e. creating multiple images of the same board on one panel for ease of assembly and increased throughput.)

Is the board warpage within specification?

Possible challenges:

Warpage can cause issues with insertion as well as clinch angle/length, especially on radial machine.

Does the PC board contain location reference holes to allow proper fixturing?

Possible challenges:

If product was previously hand assembled it may not have locating holes.

Are the components positioned at 0º and/or 90º with respect to the X axis?

Possible challenges:

Sometimes components are arranged at odd angles because of space constraints or because designer wanted to keep component body straight.  (example: ECCO board.)

Are the component hole diameters within specification for each component type (lead diameter) being inserted?

Possible challenges:

Boards currently hand assembled are most likely to have undersize holes.

Is there sufficient clearance below the board for the clinched component leads?  Consider the following:

Solder bridging to other component leads

Solder bridging to via holes or adjacent pads

Note: Universal does not specify required clearance to prevent solder bridging, this should be determined by the customer.  However, obvious cases of conflict should be noted.

Is there sufficient clearance for the insertion and clinch tooling?  Take into consideration:

Previously inserted IM components

Previously placed SM components

Workboard holder locating and support fixtures

Obstructions on the bottom of the board that could interfere with the clinch or board transfer.

Component and tooling considerations

 

Axial

Are components packaged properly for automatic insertion?  (Tape and reel/ammo pack)

Possible challenges:

Customer may have “sample” components in bulk, are these components readily available in a taped format?

Is the component input tape width (i.e. 26mm or “standard”) compatible with the component hole span?

Possible challenges:

Universal does not offer a machine that can accept 26mm input.  Virtually all components are available in 52mm format, however, a subcontractor may have to deal with “kits” from an OEM that contain 26mm components.

Is the insertion tooling (i.e. 5mm, 5.5mm or standard) compatible with the component hole span?

Possible challenges:

Does the product include both very wide and very narrow span components?  Use tooling selection matrix to evaluate best tooling fit.

Is the component hole span compatible with the component body length?

Possible challenges:

Be especially careful when moving product from hand assembly to automatic assembly.

Is the component body diameter compatible with the board thickness and insertion tooling requirements?

Possible challenges:

Watch out for very thick boards and/or large diameter components.

Is the component lead diameter compatible with the insertion tooling?  (i.e. standard vs. large lead)

Possible challenges:

May have to sacrifice (to hand assembly) some insertions at either the large end or the small end of the spectrum.

Does the component require a stand off between the body and the PC board?  Components requiring a stand off cannot be inserted with an axial inserter, but may be auto insertable with a radial inserter if packaged in the proper format.

Possible challenges:

“Stand-off” type resistors are more common where high power handling is required, power supplies, monitors, etc.

Radial

Are components packaged properly for automatic insertion?  (Tape and reel/ammo pack)

Possible challenges:

Customer may have “sample” components in bulk, are these components readily available in a taped format?

If components are packaged on tape, use the following “quick check” list to get a general idea of which components may be automatically inserted:  (See note 1 below)

Body diameter 13.0mm or less

“H” dimension (distance from centerline of feed hole to bottom of component) within acceptable limits

Lead diameter within acceptable limits

Possible challenges:

Radial taping specifications are quite involved, use “quick check” list as a sanity check, forward component samples to applications group for detailed evaluation.

Are the lead spans of the components compatible with standard automatic radial insertion?  (i.e. 2.5mm, 5.0mm, 7.5mm or 10.0mm)  (See note 2 below)

Possible challenges:

May have to “sacrifice” some components to hand assembly because of tooling footprint issues or span requirements.

Some PCB’s contain components are non-standard span’s, i.e. 2.0mm, 4.0mm.

Are transistor leads in line? (i.e. not in a “triangle” configuration)

If the component is required to stand off the PC board, are features built into the component lead to accomplish this?

Possible challenges:

Board designer may “require” a certain type of standoff without checking to see if the package is readily available, common with LED applications.

 

Notes:

1)  The simplified guidelines were created to draw attention to the most common areas where components fall outside the limits for auto insertion.  These simplified guidelines should only be used as a general guide.  Component input must meet all criteria called out in the Radial General Specification.

Tooling selection will depend upon insertion span requirements as well as board density considerations. Muniak98-052B Revised 01-00

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