metal back body phones

The Forgotten: Why Do Phones No Longer Have A Metal Back Body?

There was a time when we had the metal back body trend on flagship phones. The golden days when smartphones used to be a lot tougher than they are today. A phone with dents on the rear back telling its history, how much it has suffered by the hands of a user. However, the thing was that no matter how many times a metal phone dropped, the back body won’t even crack the slightest. Back when you didn’t need to apply a protective film on the back. As for the built and feel, that CNC laser technology cutting and the smooth cold metal feel were far superior to glass and plastic. What happened to them? Why do phones no longer have a metal back cover?

metal phone dents
An old metal iPhone with a bump on the metal case

Certainly some technologies are to blame which set off the metal trend in smartphones. Let’s get to know why we have no metal phone released these days:

1) Antenna design requirements in the 5G era are higher

Although phones with metal back body stopped coming before the 5G era, however, even if they were to present in this 5G era, running this network on those metal phones would be impossible. Why you ask?

Signal problems is the number 1 reason why a metal phone and 5G can not coexist. If you want a good signal, you have to design the antenna of your phone better. With the advent of the 5G era, 5G speeds are faster. In order to achieve a large amount of data throughput, the antenna design also adopts the MIMO design, that is, the multiple-in-multiple-out design. 5G even achieves 4×4 MIMO. Coupled with the addition of 5G, and the different frequency bands of 5G, millimeter waves may also be involved. These make the addition of 5G antennas no longer as simple as adding one. Just for comparison, 5G requires to add 5 to 6 antennas, meanwhile, for the previous 2G, 3G, and 4G frequency bands the requirement was only 1-2 antennas.

WiFi 6, Dual-Frequency GPS, UWB, and Air Charging Evolution

Of course, along with 5G, there are more other functional enhancements made to the phones these days. In terms of Wi-Fi, in addition to supporting 2.4GHz and 5GHz, today’s Wi-Fi even has 2×2 MIMO 160MHz, which also requires more antennas to achieve. There are dual-frequency GPS antennas, and even UWB, which is ultra-wideband technology, requires antennas. Recently, air charging is also in development.

Why Not Use These in a Metal Phone?

These “miscellaneous” frequency bands and technologies, coupled with the need to consider the signal blocking problem caused by the holding of smartphone while gaming or watching video, have caused the number of antennas required for phones today to be extremely complex, and the design requirements for antennas are becoming higher and higher.

The metal back shells used in the past were all made of injection molding of the antenna on the metal cover, or another option was to make it into a three-stage structure. Today, the number of antennas cannot be met at all from these two processes.

In the past, metal housings were used to make antenna receivers, but they still cannot meet today’s number requirements. At present, there are still some phones that have the antenna section on the phone holder, or even on the back of the back case. If a metal frame is used, the metal will reflect the signal, causing signal reception problems.

2) The NFC Trend Not Possible On Metal Back Body

The signal is only one aspect for the decline of metal phones, the popularity of NFC has also become one of the reasons for the replacement of the material of the back body of a smartphone. This is before the 5G era. But here, you might question that in the past, some phones with NFC function also had metal back. Is there any relationship between NFC and metal back body ?

In fact, in the past, phones that used metal back body with NFC, had the NFC antenna implanted in the injection-molded antenna of the case. Some had operations such as slot implantation of the antenna in the camera hole area. Of course, this also has certain requirements for the manufacturing process of the back cover. With the continuous decline of NFC-equipped products and the increase of functions related to NFC, that specific metal cover for NFC became a problem as the new functions were not possible on it.

Moreover, manufacturers priortize cost of manufacturing which would be quite expensive with the metal back and the glass case was a better choice.

3) Wireless and Air Charging Not Possible On Metal Back Body

Wireless charging is a great hit these days. It is the sign of premium flagships such as the Samsung Galaxy S and Note series. Moreover, we also have air charging in development as well.

Wireless charging and metal back chassis are a pair of deadly rivals to each other. This is mainly because wireless charging uses coils and relies on the principle of electromagnetic induction. This principle is applied to induction cookers. Of course, induction cookers use electromagnetic induction to generate eddy currents. These currents heat the body of cookers.

Some wireless chargers also have a foreign body detection function, that is why they are afraid that ferromagnetic metals will produce eddy current effects and cause metals to heat up and cause problems. Not to mention that the power of wireless charging of phones is getting higher and higher. This aspect still needs to be cautious. In fact, most of the metal casing of smartphones is made of aluminum alloy. Although aluminum alloy is difficult to generate eddy current heating, it will block the propagation of electromagnetic waves, making wireless charging completely useless.

4) Heat Generation While Doing Any Heavy Task or While Charging

The most important reason of all. Metal phones are notorious to heat while doing heavy tasks like gaming, video editing, and so on. God, there are some phones which can be used as an iron as well while they are charging (see the old MTK Helio X30 phones).

Metal phone heated

If we were to use the same metal phones with recent technologies, the heat dissipation would be this much that even the today’s in-built cooling systems in phone may surrender. Not to mention, that overheated phones might melth internal components as well. Moreover, on the front side, you wouldn’t like your phone to be all choppy and freezing while playing games like PUBG mobile or using camera with Pro mode and flash. Would you?

Moreover, in hot weather conditions, metal phones catching fires is also possible. See the old Redmi series with metal case history in India.

I don’t think, we will ever see phones with complete metal body again. It’s a relic of the good old days. What do you think? Let me know in the comments.