[sdiy] SMT diodes: MELF vs. SOT-23 chip?

[Richie Burnett]

The facts that they're more expensive, and roll all over the place when you 
try to put them anywhere are good reasons to use rectangular packages 
instead of MELFs.  Also, the board houses i've dealt with hate MELF packages 
because they need special vacuum heads for their pick 'n' place machines.

-Richie,



-----Original Message----- 
From: Mattias Rickardsson
Sent: Wednesday, September 23, 2015 10:56 PM
To: Tom Bugs
Cc: synthdiy diy
Subject: Re: [sdiy] SMT diodes: MELF vs. SOT-23 chip?

Tom,

no problems so far, I'm just curious if there are any reasons to
choose MELF before chips. Two MELF diodes are around 50% more
expensive (each something like €0.005 + €0.003 for mounting it, for
both = €0.016) compared to one SOT-23 dual diode (€0.008 + €0.003 =
€0.011). The MELFs also occupy more space on the PCB. But they do look
much better, with their tiny retro-style glass jar. :-)

/mr


On 23 September 2015 at 21:15, Tom Bugs <admin at bugbrand.co.uk> wrote:
> Interesting question & I hope people will respond 'on list' to share
> thoughts.
>
> I went to MELF diodes as they seemed so similar to the regular 1N4148s - 
> ie.
> for common silicon diodes apps
> Only used SOT-23s for dual schottky between rails (for protection apps) as
> it seemed such a convenient form.
>
> The only time I actively choose between SOT23 and MELF is for zeners,
> dependent on current.
>
> What's driving your question Mattias?
> Are you responding to a strange problem that has cropped up in a design?
> or...
>
> Cheers, Tom
>
>
>
>
> On 23/09/2015 18:30, Mattias Rickardsson wrote:
>>
>> I've used surface mount diodes in both MELF (glass style) and SOT-23
>> duals (chip style), but are there any significant differences between
>> these two when it comes to audio/synth applications?
>>
>> Sometimes the shape and other physical properties of simple basic
>> components can affect more than you first might think. :-)
>>
>> Thanks,
>>
>> /mr
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