Ipc A 610 F Plus 50 Thickness

Did you know there is an IPC standard associated with nearly every step of printed circuit Read More.

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Class 3 Part 1, there are many factors that determine whether a product falls under the IPC-610 Class 2 or 3.

As Circuitnet describes in their Ask the Experts, Class 2 vs.

Class 3, The major differences between Class 2 Class 3 are found in component placement for surface-mount components, cleanliness requirements based on residual contaminants on the assemblies, and plating thicknesses as defined in plating through hole and on the surface of PCBs.

Greater attention to heel fillets, precise component placement, and the absence of contaminants, increases the thoroughness of inspection required, and in turn the amount of labor directed at the production and inspection of this product.

Ipc A 610 F Plus 50 Thickness

For minimum Class 2 acceptance, minimum heel fillet height is equal to solder thickness plus 50 thickness of lead at joint side.

For Class 3 acceptance, minimum heel fillet height is equal to solder thickness plus thickness of lead at joint side.

Class 3 cannot be achieved if the air gap between pads is too wide.

The solder cannot wick up the heel of the lead if the heel is not above the pad.

The footprint has too large of an air gap, not allowing for an adequate heel fillet per IPC Class 3.

Class 2 requires a 50 barrel fill, while Class 3 requires a 75 barrel fill.

Depending on the design of the boards, this may or may not be achievable.

When designing the plated-through-hole (PTH), ACDi sets the goal of 15 mils over the diameter of the lead, as this leaves 7.5 mils on either side, allowing for paste to fill deeper into the barrel.

The smaller the PTH, the more difficult it is to get the paste into the barrel.

If the board is not designed to accommodate this, then Class 3 cannot be achieved during production.

While there is no exact spec for PTH oversize to achieve Class 3, the smaller the gap surrounding the lead, the more difficult it will be to obtain the 75 fill.

The drill breakout requirement affects via size and the size of the annular ring.

Because Class 3 allows not breakouts, annular rings must be oversized to accommodate tolerances with respect to drill sizes, drill registration, plating requirements, etc.

It is crucial to consider during the design phase what implications the design and layout will have on the ability to produce the desired Class of product.

THIS is why designing for manufacturability is an important goal; you will achieve the desired product and prevent delays during production from questions that could have been resolved on the front end.