It's a individual decision based on the conditions I mentioned. I recommend
you to consult your handbook 600 & 610 for additional and professional
guiding. Another tool for the the experienced CAD specialists at TN is,
that you send a drawing of the mount site you want be helped with. Mail it
to Steve Gregory or announce it in TN's own showroom If you do, you will
get more precise advice from the CAD gurus.
Let me also mention, without knowing your drawings, that you can avoid
bridging by designing ' solder thieves'. Again, I refer to IPC's handbooks
for further information.
Inge
.
On 30 January 2012 01:37, Jian Lin <[log in to unmask]> wrote:
> Inge,
>
> Quote 1 (Q1)
> If these have extreme height vs. width, even 0.3 mm may be too unsafe.
> Then you have to increase the space to 0.5 mm , or more in unusual cases.
>
> Quote 2 (Q2)
>
> So, I recommend the conservative >0.3 mm for hand soldering. If we discuss
> SPACE, we must apply >- 0.5 mm.
>
> In Q1, you mentioned that 0.5mm distance is only neede under the condition
> of extreme height÷width ratio; in Q2, you described 0.5mm as an
> unqualified "must".
>
> Is 0.5mm necessary at all situations or only when there is extreme
> height÷width ratio?
>
>
> Jian
>
>
> On Mon, Jan 30, 2012 at 7:41 AM, Inge Hernefjord <[log in to unmask]>wrote:
>
>> At Ericsson, from where I come, we had the following basic rule:
>>
>> whether you can get good result with 8 mils or not, it does not matter,
>> the creepage calls for minimum 0.3 mm distance between adjacent pads, and
>> this has not to do with solder mask or not, it's an undisputable lowest
>> figure (there are excerptions) . Seen from this point of view, 16 mils is a
>> good choice. BUT, the discussion is not over yet. There is an often
>> forgotten parameter that you need check out too, namely, the height of the
>> component's solder terminations. If these have extreme height vs. width,
>> even 0.3 mm may be too unsafe. Then you have to increase the space to 0.5
>> mm , or more in unusual cases.
>>
>> Many will probably announce that they CAD so little as 6 to 8 mils and
>> the production runs undisturbed. Yes, but I bet they run real fully
>> automated mass production, have large resources and have spent lots of
>> processing engineering hours on it. And we talk hand soldering. These two
>> are two different worlds. So, I recommend the conservative >0.3 mm for hand
>> soldering. If we discuss SPACE, we must apply >- 0.5 mm.
>>
>> Again, you must consider, not only soldering solutions, but also
>> electrical matters.
>>
>> There is more to speak about, but you certainly want melt this first.
>> Surprised? Well, there is a reason why tons of books are written about
>> soldering. ..n'est pas une bagatelle
>>
>> Inge
>>
>>
>>
>>
>> On 29 January 2012 22:29, Jian Lin <[log in to unmask]> wrote:
>>
>>> ---------- Forwarded message ----------
>>> From: Jian Lin <[log in to unmask]>
>>> Date: Mon, Jan 30, 2012 at 5:26 AM
>>> Subject: Re: [TN] 0.1mm countyard excess: too small for hand soldering?
>>> To: [log in to unmask]
>>>
>>>
>>> Inge,
>>>
>>> Thanks very much for the reply.
>>>
>>> How do you think of a mimimum of 16 mil separation between pads of
>>> adjacent components? It is equivalent to 16mil / 40 = 0.4mm, and can be
>>> seen pretty clearly to with normal eyesight. As you have said, 10mil
>>> separation sometimes can be soldered without problem, what about adding
>>> another 6mil separation? I would naturally believe it would make the task a
>>> lot of easier, but would this 6mil cause sometype of "sea change" which
>>> transformed from
>>>
>>> 1. 10mil separation: requiring some degree of skill
>>> to
>>> 2. 16mil separation: solderer with ordinary/avarage skill could handle it
>>>
>>> ?
>>>
>>> Quote Inge:
>>>
>>> "It's amazing how separating a 5 to 10 mil space can be if all
>>> parameters of the board are OK, and vice versa"
>>>
>>> Do you mean that that a well-designed board generally would avoid
>>> extreme small separations at this range? What about 16mil separation? Does
>>> it still indicate poor design?
>>>
>>>
>>>
>>> Jian
>>>
>>> On Mon, Jan 30, 2012 at 4:52 AM, Inge Hernefjord <
>>> [log in to unmask]> wrote:
>>>
>>>
>>>>
>>>>
>>>> Jian,
>>>>
>>>> it depends...very much depends in this case...on a number of
>>>> conditions, such as
>>>>
>>>> a. The size and the shape of the iron tip
>>>> b. The used solder wire gauge and the necessary amount of solder.
>>>> c. The used temperature of the tip
>>>> d. The used flux
>>>> e. The size of the pads
>>>> f. The quality of the finish (wetting angle)
>>>> g. The surface cleanliness of the board
>>>> h. The type of components
>>>> i. and more conditions that I don't see instantly
>>>> j. and of course the operator's skill
>>>> k. just came to think or maximum system voltages and type of media (RF,
>>>> LF, DC ..)
>>>>
>>>> I've seen our guys solder 10 mil space without any problems, and I've
>>>> also rejected boards with near-shortage solder joints. In my opinion, there
>>>> is only one way to give answer: run a test series, and freeze every
>>>> operator sequence if the result is good. If not, adjust the parameters one
>>>> by one until you can safely repeat the processs.
>>>>
>>>> It's amazing how separating a 5 to 10 mil space can be if all
>>>> parameters of the board are OK, and vice versa, it can be a hell to avoid
>>>> bridging.
>>>>
>>>> Hope you got inspiration to go on with your process evaluation.
>>>> Soldering is an ART !
>>>>
>>>> Inge
>>>>
>>>>
>>>> On 29 January 2012 12:59, Jian Lin <[log in to unmask]> wrote:
>>>>
>>>>
>>>>> Hello members,
>>>>>
>>>>> I would like to consult the following questions:
>>>>>
>>>>> IPC-7351 define “courtyard excess” for placement density level A
>>>>> (most), B
>>>>> (nominal) and C (least). And according to Note 3 on page 1, courtyard
>>>>> excess defined in IPC-7351 are for reflow soldering.
>>>>>
>>>>> In prototyping, I however need to ask a solderer to manually solder the
>>>>> chips/components. For C (least) level density by which the minimum
>>>>> courtyard excess is 0.1mm → between two components is 0.1 × 2 = 0.2mm
>>>>> = 8mil,
>>>>> and assume this 8mil distance is between two closest pads on different
>>>>> components, is this too close for a manual solderer to solder properly?
>>>>>
>>>>> There are two aspects to consider:
>>>>>
>>>>>
>>>>> 1. Solder mask is always needed to prevent bridging. If the
>>>>> separation
>>>>> is only 8mil, and considering that solder mask has expansion which
>>>>> at least
>>>>> ≥ 1mil, so that the maximum remaining width for solder mask sliver is
>>>>> only about 8-2×1=6 mil. Is this narrow sliver wide enough to prevent
>>>>> bridging?
>>>>>
>>>>> 2. Even if we could ignore the solder mask width issue, or that it
>>>>> turns
>>>>> out 6mil width is enough for solder mask sliver, we still need to
>>>>> ascertain
>>>>> that 8mil separation could be handled without difficulty by human
>>>>> hand. Is
>>>>> it very difficult for an experienced solderer to do this? How about a
>>>>> solderer of average skill level?
>>>>>
>>>>> Thanks and regards,
>>>>> Jian Lin
>>>>>
>>>>>
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>>>>
>>>>
>>>
>>>
>>>
>>
>
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