Double sided placement

[ryanrolds]

Here are the most recent (December) BoM and placement CSVs. I've used these CSV for at least 2 orders with JLCPCB. There is a new file for "standard" PCBA type and I've updated the file names to ensure clarity.

[rbaron]

Up until when I did my last order, there was a significant bump in cost for doing double-sided assembly, as opposed to single top-side only. That was the original reason for me to put all components on the top and just the battery clip on the back, which can be soldered by hand relatively easily. For most people, who I imagine order O(10) boards, I believe it is (or used to be at least) significantly cheapear to do top only and then fix the batt clip by hand.

Do you know if that's still the case?

[ryanrolds]

I just looked. Yes, it about doubles the price with 5 units ($78.34 vs $144.57). There is $50 setup free with standard PCBA over economic that is the bulk of the difference with feeder loading fees being most of the remaining.

Would having both files and updating the How to order doc highlight the differences be a good compromise? I'm terrible at soldering (software person) and I've had people email me asking for double-sided placement file.

[rbaron]

Yes I think that is a fair compromise.

Better yet would be a process that doesn't require manual editing of the csvs that are exported from kicad. If kicad can automatically generate both top and bottom separately (which I think it does) we can do that and instruct power users to merge them in the wiki.

I believe I used the now popular "JLCPCB fabrication toolkit" to generate the fabrication files.

[ryanrolds]

I've pushed some additional changes. I've also made some changes to the wiki, but I don't have the ability to push branches due to how GitHub Wiki works. How would you like the changes contributed? I have can provide a diff.

[ryanrolds]

I'm looking at the "JLCPCB fabrication toolkit".

[rbaron]

Thanks @ryanrolds.

It looks good to me. My only nit would be to rename the files to "....top-side.csv" and "....double-side.csv" so it's more self documenting.

For the wiki, I'm don't know how to grant write access, but please paste your diff here and I will edit it myself.

[ryanrolds]

Completely understand the desired for clairty. Please take a look at this diff. If you still want the names changed, I will update the PR and provide an updated diff.

diff --git a/How-to-order:-PCB-fabrication-and-SMT-assembly.md b/How-to-order:-PCB-fabrication-and-SMT-assembly.md
index fcecdd8..4633429 100644
--- a/How-to-order:-PCB-fabrication-and-SMT-assembly.md
+++ b/How-to-order:-PCB-fabrication-and-SMT-assembly.md
@@ -39,14 +39,23 @@ This is a CSV file that maps components labels in our design (such as R1 or C2)
 The [kicad/parasite.csv](https://github.com/rbaron/b-parasite/blob/main/kicad/parasite.csv) file contains the BOM for [JLCPCB's SMT assembly service](https://support.jlcpcb.com/article/80-bill-of-materialsbom-file-for-smt-assembly) with JLCPCB-specific part numbers, but it should be adaptable for other fabrication companies.

 ## 2. The pick-and-place file
-This file tells the fabrication company _where_ to put each components while placing them on board. As with the BOM file above, this is unfortunately company-specific. The [kicad/parasite-top-pos.csv](https://github.com/rbaron/b-parasite/blob/main/kicad/parasite-top-pos.csv) file contains the position of each component as required by the [JLCPCB's assembly service](https://support.jlcpcb.com/article/79-pick-place-file-for-smt-assembly). Again, this should be easily adaptable for other fabrication companies.
+This file tells the fabrication company _where_ to put each components while placing them on board. As with the BOM file above, this is unfortunately company-specific.

-### Components orientations
+> If you have placement files for other companies, please submit a pull request to add them here.
+
+### JLCPCB
+JLPCB has two options for "PCBA Type" in the PCB Assembly section of their ordering process:
+* [Economic](https://github.com/rbaron/b-parasite/blob/main/kicad/parasite-pos.economic.csv): Requires soldering the battery holder, cheapest option
+* [Standard](https://github.com/rbaron/b-parasite/blob/main/kicad/parasite-pos.standard.csv): Fully assembled, including the battery holder, but much more expensive
+
+These files contain the position of each component as required by the [JLCPCB's assembly service](https://support.jlcpcb.com/article/79-pick-place-file-for-smt-assembly). Use the file that best matches your needs.
+
+#### Components orientations
 Sometimes engineers from JLCPCB will get in touch to confirm or suggest changes to the orientation of components (see [this comment](https://github.com/rbaron/b-parasite/issues/3#issuecomment-1082222418) and [issue #42](https://github.com/rbaron/b-parasite/issues/42)).

 Here are some sanity checks:

-#### Photodiode Q4
+##### Photodiode Q4
 Q4's collector (+) should be aligned with the footprint dot. For example, in version 1.2.0:
 <img width="595" alt="Screen Shot 2022-05-18 at 20 21 52" src="https://user-images.githubusercontent.com/1573409/169117369-afd07f06-1886-477c-a795-c35469f91e63.png">

[rbaron]

Thanks. I still would like to be more explicit. Economic/standard are loaded terms in fabrication (it could be related to finishing, tolerances etc). Top-only and double-sided are less ambiguous.

[ryanrolds]

Will do. I should have some time on Wednesday.