The overall manufacturing method of flex-rigid pcb is procedural. So let’s break it down for a better understanding. These are the three main manufacturing steps of flex-rigid pcb:
|Step 1: Build flex PCB||Step 2: Flexible printed circuit board manufacturing process||Step 3: Consider physical constraints and possible chemicals|
|Loop||Hole size||Gum film|
|Sizing conductor||Fillet||Screen printed liquid coat|
|Etching||Key electroplating||Photographic liquid and film polymers|
Step 1: Build flex PCB
This is the main stage of manufacturing flexible PCB. Our main focus is to help you save basic materials. This is important if you want to get flexible circuits at a lower cost. Remember, the main material used in flexible circuits is polyimide. Compared with the FR-4, this material is very expensive. Therefore, you need to use it correctly.
In order to save polyimide, it is important to make the circuits as close to each other as possible. You can do this using nesting techniques. Almost all circuit layouts contain four parts per panel. However, by nesting, you can maximize it to 16 segments per panel. In fact, you can increase production by nesting correctly.
- Sizing conductor
- Conductor wiring
- Ground level
Step 2: Flexible printed circuit board manufacturing process
In this section, we will describe in detail what happens on the motherboard. Let’s start with the spacing and width of the conductors.
When using polymer films, the common conductor width needs to be 375 microns. The nominal polymer thick film has the ability to carry current. However, the Ag based polymer film carries almost 25% of the circuit current. The diameter of through holes in flexible PCB should be 200 to 250 microns. However, this can vary depending on the design and application.
- Hole size
- Key electroplating
Step 3: Consider physical constraints and possible chemicals
In this step, manufacturers focus on other useful components of Flex PCB. Therefore, we will basically deal with the issue of cladding and coating. There are many types of coating, and have many unique characteristics.
Here are some of the most common coatings used in the manufacturing process:
- Gum film
- Screen printed liquid coat
- Photographic liquid and film polymers