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Topic: .300 mil SMD adapters for breadboarding (and prototyping) (Read 13771 times) previous topic - next topic

.300 mil SMD adapters for breadboarding (and prototyping)

[quote author="rsdio"]
P.S.  While we're talking about breadboards and circuit boards that don't fit, can anyone tell me why it is that all of the SMD adaptor PCBs are so wide?  They end up covering 2 or 3 holes on either side of the center, and that's again a lot of real estate.  Is there a source for narrow SMD adaptor boards?  Ideally, I would prefer 300 mil.

rsdio came up with above interesting question. Many others may have asked the same question before ... the obvious answer being that the footprint/size of most SMD ICs up from 14 or 20 pins will not allow them them to be put on .300 mil wide 2-layer PCBs together with the pins/headers.

However, a simple solution would be to think vertical instead of horizontal ... as in breadboarding there is (in theory) infinite space in the 3rd dimension (up!).

Examples for this exist in various multiple degrees of freedom IMUs and other devices, so in most cases for other reasons (orientation of the sensors) - simple example.

I think almost every .600 mil (or other width) wide (2-row, .100 mil spaced) adapter can be modified into a .300 mil wide adapter by installing right angel headers ... 

The problem is where to get the long right angel headers from ... straight versions are available in variable lengths ...

A first attempt at modifying standard breakout boards below (left) ...

Would it make sense to design new breakout boards following a more refined concept like shown in the picture on the left?

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #1
Looks good. the second version should be fairly easy to route/design.

Ps. take care of the ceiling hight ;)

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #2
Maybe it would be possible to probably route the top pins down on the first design and connect them with a stock header (like the second). The headers could be slightly staggered (lower pins on the bottom, upper pins come to a header slightly above it) and maybe still use stock lengths of commonly-available header.

I drew on your image - the red is trace routing.
Got a question? Please ask in the forum for the fastest answers.

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #3
Thanks for responding!

I like the idea on the right, but it seems like the standard angle headers would not work because one side would be shorter than the other. Are right angle headers available with different length pins? A possible solution would be to design for SIP instead of DIP - that would work for sure.

I'm also hesitant to go too tall, because I often have wires and passive components passing over a DIP. If the SMD adaptor were very tall, it would divide the breadboard into left and right, with few options for crossover.

Finally, another question: I notice that header pins are really big and thick, so I worry that they would stretch out the breadboard sockets so they won't work with passive components or wires later. Anyone have experience with older breadboards that have seen a lot of header pins?

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #4
To get to .300 mil width you need to use one standard right angel 1-row and one standard right angle 2-row header and remove the inner pins on the 2-row header if you want to go with standard components ... I don't know of any .100 right angel one-row headers that would give you  a symetrical width of .300 mil. ... there may be some out there and custom headers/connectors are always an option for big quantity and big $$$ ... the PCB will have to be slightly thicker than standard as well ;)

Anyway, you can mount the two headers one way or the other so you can chose which side of the PCB has the "longer" pins ...

I have worked with breadboards for over 20 years and used headers on them without ever encountering a problem. True, the headers will fit in a bit tighter but then we always used them to attach other circuitry via flat-ribbon cables and they give stability :) ... then the same headers are used on breakout boards(in most cases since many don't want to pay extra for the more expensive round-pin headers)  ... so it won't make any difference if you use standard, flat breadboards or horizontal breadboards with standard headers.

Attached a "more correct" drawing and "proof of concept" pictures ...

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #5
Here a pic of a well over 20 year old breadboard (next to the full size Seeed board - looks like a rip-off of the original^^) ... must be from around 1985 and survived quite a few generations of headers ... it's (still) my favourite one :D

... until then I used wire-wrapping to build prototypes and test circuitry ... a very solid and reliable technique for rather complex prototypes and low quantity production ... just found one of the old wire-wrap guns ... it's still working :)

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #6
Some guy (microinventor) on ebay sells a few vertical tqfp adaptor boards.  He does 44, 64 and 80
tqfp and they span .3" on a breadboard.  The trick is that there are two lengths of right angle pin
headers and you solder it while plugged into a breaboard.  Attached is a picture of one in use.

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #7
JimNarem, thanks for the picture and the information. I thought there must be someone out there who came up with this vertical .300" spaced idea well before we started discussing it on this board.

The design is real efficient, the triangular shape optimizes board space so he gets 4 PCBs out of the material you would most likely get only 2-3 rectangular formed boards from.

I think going vertical in breadboarding is the way to go for complex chips/circuits - in the spirit of an expression dancers sometimes use:
vertical design (dancing) is the expression of horizontal desires ... ;)

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #8
If anyone actually wants to make a more useful version of thses vertical SMT adapters I've got a
few ideas after using a lot of different sioc, ssop and tqfp adapters from different vendors.

These things need to be as generic as possible.  I've got drawers full of them, all different.
Most of them just have the basic device footprint routed to the pins on the edge of the board.  That's
easy to layout, but most devices are on a standard pitch, so some thought can produce a generic
footprint that a range of devices will fit.  My favorite version of this is the "digole 337" (ebay seller "dig-ole"),
pictured below.  It's for 0.8mm tqfp from 32 to 48 pins.  The footprint is pretty tricky, and asymetric
but it actually works.  They make another one for 0.65mm pitch tqfp 44 to 80 pin (and 0.5mm on
the back side).  It looks similar but has double row pins at the board edges.

The flaw with these things is that they don't fit a solderless breadboard.  I stick them to thru-hole
grid breadboards (second picture shows a digole 337 socketed to a Sure Electronics MCU board).
You can also use IDC connectors or cut breadboard jumper wires and attach 0.1 molex connectors
(16-02-0103) and jumper pin headers to a breadboard.  Basically it's either very ugly or very committed.

That's where the vertical, microinventor style board comes in.  His board only works for a single footprint;
it needs to be made generic via the digole footprint.  Similar boards could be made for soics which are
all the same pitch and just differ in width and pincount, same for ssops (with a few exceptions).

The other issue with these boards, especially when used with microcontrollers and fpgas is that they
all want a few things as close as possible to the chip.  Power supply decoupling caps, crystal+caps,
fpgas want oscillators, and anything with lots of pins wants a jtag or ISP connector.  It would be nice
to have room for that, but not connected to the footprint so it remains generic.

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #9
I stumbled upon this one: ... 4-pin.html

they come in various pincounts. Robotshop appears to have various converters to breadboard. The only solderable I see are small ssoic or tsop, unfortunately not tqfp and such

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #10
UNI-SIP - Universal Single-In-Line Package for Through-Hole Components  (Pins on .100 in (2.54 mm) Centers)

Surfboards 6000 - Surface Mount Breadboards for Discrete Components  (Pins on .100 in (2.54 mm) Centers)

Surfboards 9000 - Breadboard with SMD Components  (Models for 8, 14, 16, and 20 Pin SOICs and 20 Pin PLCCs)

Surfboards 33000 - Application Specific Adapters  (Single-In-Line Pins on .100 in (2.54 mm) Centers)

Custom Circuit Manufacturing - SIP and DIP Packaging Available

Capital maintains an extensive capability to produce custom Surface Mount circuit modules in both SIP (single-In-Line Package) and DIP (Dual-In-Line Package). We can provide all required design and tooling services and produce your circuits in volumes ranging from a few dozen to a few hundred thousand. Custom circuits produced range from simple component arrays and networks to complex circuit modules.

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #11
While looking for software projects that will support Ian's latest project (or vice versa) - the FT232RL based Inexpensive multi-chip programmer - I stumbled over an other interesting "let's-go-vertical" project, openschemes "CPLD based 74xx general-purpose replacement module":

The nifty idea about this module is the combination of one quite powerful CPLS module with 14 ... 24 pin .300 sockets ... depending on the demands of the application ... the CPLD module being mounted vertically on the socket.

Based on this (or a similar) design a "standardized" family of vertical modules with 14 ... 28 pin .300 and 24 ... 40 (64) pin .600 socket adapters could be derived.
Essentially the users could decide if they want to use DIL socket adapters or directly solder in right angle headers like described further above ...

Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #12
Besides the vertical design, i like very much the idea of having a general 74xx chip.

It is a nice article to read btw: ... rogrammer/

What kind of connection do they use? The picture isn;t very clear (to me ;))


Re: .300 mil SMD adapters for breadboarding (and prototyping)

Reply #13
[quote author="Sjaak"]What kind of connection do they use? The picture isn;t very clear (to me ;))[/quote]I don't know, but it sure looks promising. The DIP adaptor would hopefully be available separately, so that any PCB could be attached to an adaptor.

The photo makes it look like a connection that can be unplugged, but it looks quite small. Certainly smaller than the typical 100 mil header.