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Re: Question to Albert

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On 9/18/2014 3:08 AM, Paul E Bennett wrote:
> rickman wrote:
>
>> I reading a bit of the blog by Yossi Kreinin and found the following
>> comment by Albert van der Horst...
>>
>> http://yosefk.com/blog/my-history-with-forth-stack-machines.html#comment-2536
>>
>> "And the pinout! Only hobbyist would try those chips out. There are no
>> pins,, just solderareas, with a stride of .4 mm (not mils, 400
>> micrometer). Hobbyist trying those out would be probably my age (over
>> sixty)."
>>
>> The context is the GA144.  I have to agree with most of what he said,
>> but I don't understand the portion quoted above.  I assume he is
>> complaining about the package rather than the pin out.  In reality I
>> think the package was one of the best choices they could have made.  In
>> the real world size is a *huge* factor for ICs these days and this was a
>> great tradeoff between size and usability.
>>
>> While many devices are shipped in BGA sorts of packages (FPGAs and many
>> CPUS) this device is in a no lead quad flat pack.  No, this is not so
>> great for prototyping by hand, but prototyping by hand is virtually gone
>> in the professional world.  Nearly every project uses a PCB on the first
>> revision of the board and plan for two or even three spins of the board
>> total.
>>
>> I like the package because the dimensions are compatible with relaxed
>> 6/6 mil trace and space design rules.  This allows a lower board cost.
>> Heck, I can get protos from oshpark.com for $10 a square inch with 5/5
>> design rules.  (a great deal btw, 3 boards, 2 weeks @ $10/sq inch)
>>
>> I hope I understand what Albert meant and am not just ranting about
>> nothing.
>
> Like Albert, I am also over 60. However, I do not see what the problem is
> with the GA144 even for hand soldered prototype. It probably takes a
> properly laid out PCB as your basis but the soldering in task is quite easy
> to accomplish. My most recent experience with this was on a tiny IC package
> (20 pins) with similarly close pin-spacing.  The technique is to flood
> solder across all pins then use solder-wick to pull the excess away. I find
> a decent angle-poise magnifier is handy when doing this sort of thing and
> access to a microscope for final inspections.

Yes, it shouldn't be that bad.  I've never used this technique as my 
time for soldering has passed.  My hand is *very* unsteady these days. 
I bought three of the GA144 from Schmartboards with the, not so well 
thought out, adapter boards but had them solder at least one of them for 
me, maybe it was two... lol  They only charge a couple of bucks extra.

But then their adapters are special.  They have channels in the top of 
the PCB with the traces in the groove and solder already pooled in them. 
  I think it is intended for leaded parts, but they seem to think it 
works well for QFN parts.  I think the idea is the raised PCB material 
acts as a better separator than solder mask and the bridges don't form 
so easily.

-- 

Rick

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Thread

Question to Albert rickman <gnuarm@gmail.com> - 2014-09-17 20:27 -0400
  Re: Question to Albert Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2014-09-18 08:08 +0100
    Re: Question to Albert rickman <gnuarm@gmail.com> - 2014-09-18 03:55 -0400
    Re: Question to Albert albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-09-18 10:37 +0000
      Re: Question to Albert rickman <gnuarm@gmail.com> - 2014-09-18 16:30 -0400
      Re: Question to Albert Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2014-09-19 01:11 +0100
    Re: Question to Albert Brad Eckert <hwfwguy@gmail.com> - 2014-09-27 17:10 -0700

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