PCBA for Car Audio
This PCBA was manufactured for one of our Brazilian customers. It is used for car audio. This customer specializes in home and car audio and is a world renowned brand in car audio.
The board material is FR-4 and TG130-140, and the surface treatment technology is lead-free HASL RoHS. The thickness of the board is 1.6 mm. The color of the solder resist layer is green. Screen printing is done with white, permanent organic non-conductive ink upon request. It has 2 copper layers, each copper layer is 1 oz thick. The dimensions of the single PCB are 214mm * 95mm. We designed two single PCBs on one panel. All panels are V-notched with a 7mm edge on each long side of the panel. The dimensions and tolerances are in accordance with ASME Y14.5-2009 standard. The PCB has many pads and has many electrical checkpoints. 100% tested for open and short circuits. We have a test frame to test this PCB. We manufacture and test to IPC Level 2 standards.
The components of this project are not particularly close to each other in terms of pin spacing, the distance between pins is greater than 0.5 mm and there is no BGA. The thickness of the stencil is 0.12 mm.
The PCBA is double-sided SMD and double-sided insert. First, we need to perform SMD on one side. Then do the other side. As each board comes out of the reflow machine, the SMT technician will visually inspect it. After the initial appearance inspection of the SMT, the quality inspection technician will check both sides of all PCBAs.
After the quality check technician inspects the SMDs, they are transferred to DIP soldering. All LEDs must be the same height and have isolation posts on the legs to prevent short circuits and to prevent the posts from being skewed during shipping or use (because as we all know, dips and bumps can happen when a car is driving on rough roads). We cut the legs to the same height as the customer requested and then install the isolation posts. All these tasks will be completed before DIP.
As far as assembly is concerned, this PCBA is not difficult and has a high yield. It does not require us to install the chip program, but it must be well tested for functionality before it leaves the factory. The customer provided us with detailed test procedure instructions. The necessary test equipment and adapters were provided.
Adapter board for powering the board. The required voltages are. 5,00V, 15,00V and -15,00V (all with ±5% tolerance).
Calibrated AC voltmeter (true RMS type).
Calibrated ohmmeter (at least 100,00kΩ).
Calibrated function generator (sine wave output required).
In short, the test steps are as follows.
Disconnect the PCBA from the adapter board and test the resistance between the first and second pins and the third pin in the connector CON. The data must be within the parameters and accuracy provided by the customer.
Connect the development board to the power supply and turn on the power. Press each switch separately and check that the LEDs are energized with the correct color.
Test the amplitude of the solder board by turning the knob clockwise to produce the corresponding sine wave, then turn the knob counterclockwise to test the amplitude of the corresponding sine wave. This procedure needs to be performed in sequence for each knob. At the same time, press the corresponding switch to check the correct status of the LED when each knob is rotated in different positions to obtain different amplitudes of the sine wave.
Turn the button fully counterclockwise to obtain another sine wave value and test the voltage of the PCBA.
There are 37 steps in total. The average test time per board was 15 minutes. In the first batch of the project, after testing, we found that some values were different from the reference range in the customer's guide. We immediately reported the problem to the customer and after analysis the customer's engineers updated the test guide to us.
We are currently using the third and final version of the guide. Here is the data report for the project. Each PCBA has a label on the bottom that shows the manufacturer's name, date code, test file recovery, and PCBA part number. We scan the test data of each batch of PCBAs to our customers before shipment for easy inspection and traceability to the source.
Our PCBA packaging is usually protected by PP foam. When shipping sample orders, we use PP foam packaging for protection and then use cardboard as an isolation film according to the shape of the PCBAs. However, the customer found that two LEDs were broken during the shipping process when he received the goods. Our analysis might be that the cardboard was crushed and deformed during the shipping process due to the violent loading and unloading, which caused the LEDs to be damaged.
Later, we made an insulated blister box for the PCBA, which is in better shape and more durable. After modifying the packaging, each circuit board received by the customer was intact.
The customer was very satisfied with our solution.
This customer has two series of car audio control panels made by our company, and we produce several batches per year. This is one of them. The new series has been developed and we have produced PCBA samples for them to test.