I think the Vintage Mac people who want to build this kit are seasoned enthusiasts, so they're used to soldering about 3 RAM's. I would be happy if even people who are unfamiliar with repair and handmade products would purchase this memory card with the hope that they might be able to make it.
This kit costs only 8 USD, and I think the shipping fee will be higher if you send this kit from Japan. However, unless Japan Post or the government solves the problem of shipping, it is impossible to send as cheaply as in China. I would appreciate it if you could buy it with other items or share the purchase with your friends. It is a very high quality board and I would recommend it.
Production method
Step 1, break the card
This card has a circuit of four cards printed on one sheet. Just like KitKat chocolate, if you break it, it will become 4 RAM cards. The thin parts on both ends are hard to break, so please use pliers. If the glass fibers protrude, sand them a little with a stick file.
Step 2, remove the chip from the 72-pin 16MB card
Make sure the 72-pin 16MB card works on another Mac that can install it beforehand. The available RAM chips are detailed here. If you decide you don't need a Parity chip, you don't need to install it. Use a hot air station for removal. The temperature is around 350 degrees Celsius.
Once removed, use a solder wick to remove excess solder, then clean the legs with IPA and a brush. You may be worried about the heat when you remove it, but RAM chips are surprisingly heat resistant.
Step 3, solder work
Before soldering, mask the edge of the 30-pin card to prevent solder from sticking to it.
Solder the RAM chip first. In this case, solder the two legs at the end to correct the position, then solder the whole. Do this with three chips. *If parity is not required, there will be two chips.
For beginners, the trick to good soldering is to use a knife-edge soldering tip. Less solder and more flux. (*I wrote this tip below)
If there is a lot of flux, the more time passes, the harder it becomes and the more difficult it becomes to remove the flux.
Once the RAM chip is soldered, attach the 3 capacitors. Capacitors are 1206 size 0.1uF 25V to 50V SMD. Soldering chip parts is easy if you don't use too much solder. Use a lot of flux.
When installing an LED, attach a 330ohms resistor to the 331 part and attach an LED to the back. Both are 1206 size. The orientation of the LEDs is shown below.
Step 4, cleaning and checking solder
Wash carefully with IPA. Make sure the flux is completely removed. Solder failures are often bridging the inner part of the SOJ involved. Blot them with a solder wick, or apply a generous amount of flux and separate them using a fine-tipped soldering iron.
Conversely, if the legs and pads are not soldered, it is most likely that the temperature of the soldering iron is too low or that the soldering iron is not applied sufficiently. It is highly possible that the solder is difficult to get on the pad to the ground because the heat escapes.
Step 5, check the operation on the logic board
If it is a Mac that can check the operation one by one, check the memory cards made by one, two for Classic II, and four for SE/30 or IIci. If the memory card doesn't work or is Simasimac, check step 4 again.
The memory card is 1.2mm, but it can be used without problems in a socket that maintains the strength of the spring. If the spring is weak, reattach it several times or add a little more solder to the edge of the card.
The view is exhilarating when 4 matching cards are mounted on the logic board! If you install 8 cards, it will be 32MB, so I think you can be satisfied in most cases.
Tips!: For those who are not good at soldering SOJ or PLCC ICs
Those who are not good at soldering SOJ and PLCC are probably those who do not give enough heat to the pads.
See the diagram below. Use a knife-edge soldering iron tip. If you are using a Hakko soldering iron, the part number has a K at the end. (T12-K, T12-KF, T12-KL, etc.)
The first thing to notice is that the green edge and the red pad surface are in perfect surface contact.
For the feet, even if the angle of the tip of the iron is not good, they are rounded, so heat is easily transmitted.
Even if the solder looks good at this point, if you look at the back, the solder tends to collect in the J-shaped part, so it is often the case that the solder is bridging inside the chip.
What you should be aware of is that there is very little solder.