Assuming similar characteristics in design, why would one choose an SOJ-36 vs TSOP-44 package format for something like an SRAM component?

Again, assuming the same size SRAM, speed, power, etc.

SOJ-36 looks a little more compact but isn't really that big of a deal? Both are tiny to my old eyes.

Thanks for any input.

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Cat; the other white meat.

Looks to me like TSOP is smaller and also much thinner, but a finer pitch. So, you might choose it for thinness (unlikely to be an issue in hobby land) or you might choose SOJ for the coarser pitch, which might make it easier... except, soldering TSOP must be easier because you can get to the leads, and with SOJ you can't. I think Garth has said he's sometimes bent the leads of an SOJ to turn it into something more solderable.

That's a good point. The TSOP looks to be easier to solder despite the thinner profile. How are SOJ's soldered to boards typically? Or, are they not very common for hobby projects?

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Cat; the other white meat.

I used an SOJ32 SRAM in POC V1 and manually soldered it.


POC V1 also has an SOIC24 package. which is near the left end of the board.

Garth's 4MB DIMM is built up from SOJ36 SRAMs, which he manually solders. POC V2 has two SOJ36 SRAMs that were manually soldered.


TSOPs can be manually soldered as well. This video gives a good explanation of manual SMT soldering in general.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

That's funny because I was literally looking at that picture a few minutes ago for another topic I'm researching.

I guess I'm confused on the benefits of SOJ at all. Other than the pin spacing?

I should be able to solder either one. I have a pretty good magnifying lamp and I can solder 805 resistors without too much trouble.

Anyway, if you were to create POC3 (or 4?) would you still use SOJ?

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Cat; the other white meat.

My guess would be that SOJ was among the earlier ideas for SMT - it's rather like DIP, but modified. Much more robust in handling than the likes of TSOP, too.

SOJ packages, such as PLCCxx, can be socketed, which made them attractive back in the days when reflow soldering was not as common and as reliable as it is now. If memory correctly serves me, the SOJ package form has been around since the late 1970s, and was one of several package forms originally standardized by the old EIAJ and subsequently adopted by JEDEC.


Yes. At this time, the largest SRAMs that are available that operate on 5 volts are 512KB parts in SOJ36 packages.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Incidentally, Wikipedia has a reasonably good article about SO packages in general.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

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http://WilsonMinesCo.com/ lots of 6502 resources
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I'm the one. It took me a while to find where I'd posted this! But it's on page four of Techniques for reliable high-speed digital circuits.

There's lots you can do with J-leads -- I'm quite comfortable with them (and the .05" spacing). But be sure your soldering iron is one with a fairly fine, conical tip. Chisel-shaped tips are not what you want.

I've also worked with the packages with finer pitches (below .05") but the soldering technique is different. Rather than soldering individual pins, you flood ALL the pins with solder then remove the excess. It's not terribly difficult, except that stuff that small is so darn hard to see !

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