Thanks to all!
This was very helpful.
Have a great day!
On 2/26/2013 7:23 AM, Karl Bates wrote:
> JF,
> I would consider how the hole is used, is it a mounting hole ? Then you should check the size of the hardware (screw head, stand off etc.)
> and allow some tolerance adjustments and make the soldermask opening larger than the hardware (don't expose adjacent copper of course).
> And that means adding keepouts that will help you keep the copper out of that area.
> Is it a tooling hole, just used for test or alignment during assembly ? Then I would just oversize the soldermask 4-5 mils.
>
>
> Karl
>
>
>
>> Date: Mon, 25 Feb 2013 22:36:10 -0400
>> From: [log in to unmask]
>> Subject: Re: [DC] Solder Mask requirements for unplated holes
>> To: [log in to unmask]
>>
>> Hi JF,
>>
>> I didn't find a soldermask spec for unplated holes, however the spec
>> according to IPC-7351 is: "PCB Manufacturer are required to keep
>> soldermask material off the land. Clearance conditions can vary from
>> 0.0mm(0.0") to 0.1mm (0.004")".
>>
>> I recommend you to choose the best one that fits your design rules
>> requirements. There are clearance requirements from copper to mounting hole
>> (hardware, screws, etc) you should look into it.
>>
>> Hope this helps,
>>
>> Regards,
>>
>> Glennys de Jesús, CID+
>>
>>
>> 2013/2/25 Greg Smith <[log in to unmask]>
>>
>>> The answer is, of course: It depends.
>>>
>>> The size of the mounting hole, the distance the copper is pulled back from
>>> the hole, and the board material used can all affect the location of the
>>> mask edge. And also your design intent.
>>>
>>> You want to be sure the mask does not leave any copper exposed so the
>>> tolerances for your shop/processes determine that.
>>>
>>> If the mounting hole is for a typical sized screw it will be large enough
>>> you can have the mask opening dia just a bit smaller than the hole dia as
>>> there will be little chance of the mask clogging the hole. Do not make the
>>> mask opening dia zero as the shop will have to make there own choice there
>>> as a large opening in the screen will mean too much mask gets squeegied
>>> thru and will need to be cleaned off the back of the screen too often.
>>>
>>> If you are using a board material such as teflon, for RF for instance, do
>>> not run the mask to the edge of the hole or beyond (or the edges of the
>>> board). Since the mask does not adhere well to those materials an edge can
>>> be a location where the mask can catch and be easily peeled back, espcially
>>> by hardware going through the hole.
>>>
>>> Greg Smith
>>>
>>>
>>>
>>> On 2/25/2013 11:37 AM, JF wrote:
>>>
>>>> Hi All,
>>>>
>>>> This should be basic, yet I can't remember the requirement nor where to
>>>> find the info (which spec).
>>>>
>>>> We have a board with some unplated holes and a copper plane on both the
>>>> top and the bottom. Of course, the copper planes are recessed from the hole
>>>> but I can't remember if the Solder Mask should be flush to the holes (some
>>>> are mounting holes), or just covering the planes + a certain distance.
>>>>
>>>> Thanks in advance!
>>>>
>>>> JF
>>>>
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