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Aluminum PCB Manufacturing Process - A Quick Glance in a PCB Factory

PCBONLINE Team

Tues, May 10, 2022

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Before you decide to place an aluminum PCB order, you may wonder, how are aluminum PCBs made from a factory? Will the aluminum PCBs' surface be scratched or even scraped when being carried during the manufacturing process? How do they drill and route the boards? First, the aluminum PCB manufacturer PCBONLINE tells you that aluminum PCBs won't be contaminated, scratched, or scraped on our fully automatic production lines.

PCBONLINE achieves industry 4.0 full automatic aluminum PCB fabrication. The below content reveals the aluminum PCB manufacturing process step by step with images.

Step 1: Preparing Aluminum PCB Laminates

For single-sided one-layer aluminum PCBs, the first step of aluminum PCB manufacturing is preparing and pre-treating the laminates.

At PCBONLINE, this step is done automatically on automated guide vehicles. This is because we need to prevent scratches that result from carrying laminates.

The automated guided vehicles not only transfer the laminates from the laminate warehouse to the production lines. In the following steps, they will transfer the boards to the end of the production lines and finally to the PCB warehouse.

aluminum PCB preparing laminates

You can see the below single-mounting-sided one-layer aluminum PCB laminate structure.

single-sided aluminum PCB laminate

PCBONLINE has cooperation with the laminate supplier Ventec, and we use aluminum PCB laminates from Ventec, Shengyi, Arlon, Polytronics, Toking, and our own laminate factory Yugu.

Note
This step-by-step manufacturing guide is only for single-mounting-sided one-layer aluminum PCBs. Please look at the manufacturing of single-mounting-sided two-layer aluminum PCBs, dual-mounting-sided two-layer aluminum PCBs, and dual-mounting-sided four-layer PCBs after these steps.

Step 2: Generating Circuits on the Copper Layers

During aluminum PCB manufacturing, generating the circuit on the copper layers is the same as generating an inner circuit layer on other PCBs, We place a film drawing the circuit image above the copper layer that is covered by photoresist liquid.

Under the UV light, the photoresist under the circuit image hardens and forms a protective film. While photoresist in the rest areas is still liquid and is washed away.

And then we use sodium hydroxide to etch away exposed copper. In this way, only copper in the circuit image remains. And then we peel off the photoresist film and get the required copper circuit traces.

Step 3: Drilling Positioning Holes on Production Panels

aluminum PCB positionig holes

On aluminum PCBs, positioning holes are designed for screw connection with other parts and the product shell. As the manufacturer, we also need to design positioning holes on technology edges for punching and routing.

We pouch out positioning holes on the production panels using a punch press.

Step 4: Solder Mask Printing

Solder mask printing on aluminum PCBs has no differences from other PCBs. Under the UV light, the solder mask ink gets dry in the exposure-development method. And then the panels are baked in an oven to let the solder mask totally cure.

Since aluminum PCBs are mainly used for lighting, the solder mask color is usually white. Many customers choose 85% light reflective white solder masks.

aluminum PCBs

At PCBONLINE, the tolerance of applying white solder masks on aluminum PCBs is 3mil, and that of black solder masks is 4mil.

Step 5: Silkscreen Printing

Silkscreens are the text and symbols printed on the solder mask to mark the components, polarity, quality standards, and the company logo. PCB ink is pressed and printed on the circuit boards through a stencil with openings.

Step 6: Surface Finish

At this step, the exposed copper PCB pads are sprayed, immersed, or plated with an antioxidant and solderable film, which is called the surface finish. At PCBONLINE, surface finishes on aluminum PCBs include ENIG, OSP, lead-free HASL, immersion tin, immersion silver, and immersion gold.

Step 7: Punching and Routing Aluminum PCBs

Here we come to the last manufacturing step, punching and routing. Usually, aluminum PCB punching and routing are completed on the same machine so we include them as one step.

At PCBONLINE, aluminum circuit boards are punched and routed on an automatic stamping production line. The punch press forces the die to go through the aluminum PCB panels to form NPTH vias. At the same time, the other extra areas on the production panel are also sheared out. In this way, we get the shaped aluminum PCBs on a panel.

For PCB assembly and conformal coating needs, we usually design technology edges on the production panel. At this step, technology edges are also punched out.

And then along the technology edges and designed separation lines between adjacent PCBs, we cut off 2/3 PCB thickness to create V-cuts for PCB depanelization

After that, we remove the possible burrs on the edges. Now, we get production panels with 4, 6, 8, or 9 pieces of aluminum PCBs panelized.

Does aluminum PCB manufacturing come to an end now? No, we still need to test the boards. At PCBONLINE, aluminum PCB testing is also automatic because we don't want to contaminate the boards by hand. The tests on aluminum PCBs include jig testing and the power-on self-test.

Note
The above aluminum PCB manufacturing process is only for single-sided one-layer PCBs. For single-sided two-layer PCBs, dual-mounting-sided two-layer PCBs, and dual-mounting-sided four-layer aluminum PCBs, the production process is different.

Manufacturing of Two-Layer Aluminum PCB with Single Component Mounting Side

single-sided two-layer aluminum PCB

For single-sided two-layer aluminum PCBs, we first manufacture two-layer PCBs and then laminate them with the dielectric layer and the aluminum base.

Manufacturing of Two-Layer Aluminum PCB with Dual Component Mounting Sides

double-sided two-layer aluminum PCB

For dual-mounting-sided two-layer aluminum PCBs, we first locate the PTH vias on the aluminum base and drill larger holes.

Around the required PTH vias, we fill with resin to insulate the via and the aluminum base because copper and aluminum are both conductive.

aluminum PCB manufacturing

After that, we laminate two dielectric layers and then two copper layers on the two sides.

Then the following manufacturing process is the same as two-layer PCB production.

Manufacturing of Four-Layer Aluminum PCB with Dual Component Mounting Sides

double-sided four-layer aluminum PCB

Dual-mounting-sided four-layer aluminum PCB manufacturing is the same as the above dual-mounting-sided two-layer aluminum PCB. The only difference is that after manufacturing the two-layer PCB, we laminate it with an alternating layer of FR4 and copper on its two sides.

Below is an example of a four-layer aluminum PCB project done by PCBONLINE. This is the metallographic analysis image of the aluminum PCB.

four-layer aluminum PCB

Industrial 4.0 One-Sop Aluminum PCB Manufacturing

If you are looking for aluminum PCB manufacturing, whether your design is single-sided one-layer, single-sided two-layer, dual-mounting-sided two-layer, or dual-mounting-sided four-layer, you can ask PCBONLINE to bring your design into reality.

PCBONLINE is a one-stop aluminum PCB manufacturer founded in 1999. With 5 fully automatic production lines and our own laminate factory Yugu, we have already achieved industry 4.0 aluminum PCB manufacturing.

Here are reasons for you to work with PCBONLINE for aluminum PCB manufacturing:

    • We can customize aluminum PCB thermal conductivity in the range of 1W/mK to 9W/mK.
    • We have the capabilities to manufacture HDI aluminum PCBs.
    • Cost-effectiveness due to fully automatic production. Only $30/㎡ for bulky aluminum PCBs.
    • Aluminum laminates from Ventec, Shengyi, Totking, Polytronics, Arlon, Laird, Bergquist, and Yugu are available.
    • One-stop aluminum PCB production, including prototyping, bulky manufacturing and assembly, component sourcing, and end-product assembly.
    • Free one-on-one engineering support throughout your aluminum PCB project.

If you have any aluminum PCB needs, please feel free to contact PCBONLINE by email at info@pcbonline.com.

See an Example: Four-Layer Aluminum PCB

Still wondering about the one-stop aluminum PCB manufacturing capabilities of PCBONLINE? See the below double-mounting-sided four-layer aluminum PCB designed and manufactured by PCBONLINE.

four-layer aluminum PCB sample

four-layer aluminum PCB structure

Wrapping Up

This blog illustrates the single-sided one-layer aluminum PCB manufacturing process step-by-step, and also introduces the manufacturing of single-sided two-layer aluminum PCBs, double-mounting-sided two-layer aluminum PCBs, and double-mounting-sided four-layer aluminum PCBs. If you still have any questions about aluminum PCB manufacturing, please ask us from the online chat window on the right or leave your comments below.


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