Automated Assembly

A project log for No-Worries Parallel Battery Charging Station

A safe (and better) alternative to parallel battery charging .

Bud BennettBud Bennett 09/17/2021 at 15:310 Comments

There are a lot of components on this board. It takes me 3-4 hours to pick and place all of the components properly and solder the board with a hot air station. Even then, there is a period of time required to insure that there are no open or missing connections, which are difficult to see.

JLCPCB Assembly:

JLCPCB offers an automated assembly service that will save a lot of time if you need to make multiple boards. The only catch is that you must use only components that JLCPCB offers, or components that are available through its sister company LCSC. 

You can engage the service by clicking on the SMT Assembly button after you have uploaded the Gerber files to the website. This will require you to decide a few options:

In my case, I chose to have 5 boards assembled. They will only do single sided assembly which is not a problem since all of the SMD components are on the top. After you confirm your decision, you click on the NEXT button to go to the next page where you have to upload two files: your BOM and the CPL. These files are available in the files section of this project.

You are then presented with a comprehensive list of components to verify. JLCPCB has two kinds of components: 1. Basic components they already have loaded on the pick&place machines and there is no labor fee to use them, 2. Extended components require a $3 labor fee per component. I needed 8 Extended components for this design. In one case it was much cheaper to use the Extended JST3401 in place of the Basic AO3401. The design requires 144 pcs of this transistor and the price differential more than made up for the $3 fee. I also decided to use a Y5V rated capacitor instead of an X5R because I could not find a Basic 2.2uF capacitor rated for 50V/X5R and did not want to pay $3 for it. 

If they are low on stock, they will not place that component -- you will need to solder it yourself. At the time I write this they would not place the AON7405 PFET or the TPS79050 regulator. You can change components on the fly by selecting the problem component and providing a substitute from their catalog. I substituted a Si7101DN for the AON7405 and got this message:

Apparently, they don't have the footprint for the part already constructed and won't provide one until they get the money for the order. Fair enough. In my case, I just deleted the PFET and hand assembled them because I had some already on hand. I also deleted D1 from the build because I was not sure their pick&place would properly solder the substitution of a 1206 resistor for a SOD23 diode.

After you verify the component list the next page includes an image of all of the parts placed on the PCB. My Diptrace program had a lot of parts that had incorrect rotation. I fixed all of that before submitting the order -- the project's CPL file has the corrected rotation. At this time a quote for the cost is also provided:

The above quote includes the Si7101DN PFETs. JLCPCB offers a coupon to take $8 off the order. So you get 5 assembled boards for around $20/each + shipping. You still must add the TPS79050 and all of the through-hole components to the total.

Here are three of the 5 boards that I received after I soldered the missing components:

I'm still missing the four XT60pb connectors. I'm really impressed by the results! No misplaced components or bad solder joints. Highly recommended.