在 PCB 打样厂几乎能做任何想象得到的板子、并把各种原型制造工艺向爱好者开放之前，在家自制 PCB 有好几种方法，其中不少要用到刺激性化学品，而且很容易失败。比如用碳粉转印法做单层板，就得练上一阵子（还得配通风柜）才能做好。Bettina Neumyr 正在做一块双层 PCB，为了在多了第二层的复杂度下依然做对，她拿出了一招新技巧。
方法的起点其实就是一块普通的单层板。碳粉被熨烫到覆铜板上（她用的是覆膜机），随后板子可以进入酸浴，把没有碳粉覆盖的铜全部腐蚀掉。但如果第二层露在外面，另一面就会被完全蚀穿。Bettina 的新做法是：在第一道腐蚀期间，用记号笔的墨水把那一面涂起来保护住。
第一面蚀好后，把墨水和碳粉洗掉，第二层仔细对准、再过一遍覆膜机，然后把相反的一面涂上墨水，进行第二次酸浴。
整个流程结束、多层墨水和碳粉都清除干净后，Bettina 就得到了一块可以焊接元件的 PCB——只是被墨水染得有点脏。至于这块板子具体要用来做什么，她故意留了悬念，说要等下一期视频揭晓。她的作品通常围绕老电子杂志上的设计展开，所以几乎可以肯定是那类东西——而这也正是为什么这块板不能直接丢给打样厂去做。
本文来源：https://hackaday.com/2026-09-29/improved-double-sided-toner-transfer-method/
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Before PCB prototyping fabs could make virtually any board one can imagine and made various prototyping processes available to hobbyists, there were several ways to make PCBs at home, many of which involved harsh chemicals and were prone to failure. For example, making single-layer boards by toner transfer took a fair amount of practice (as well as a fume hood) to do well. Bettina Neumyr is making a double-layer PCB, and to still get it right despite the added complexity of a second layer, she has come up with a new trick.
The method actually starts with an ordinary single-layer board. Toner is ironed onto a copper-clad board (she uses a laminator), after which the board can go into an acid bath to etch away all the copper that is not covered by toner. But if the second layer is left exposed, the other side would be completely etched through. Bettina's new approach is to protect that side by coating it with marker ink during the first etching stage.
After the first side is etched, she washes off the ink and toner, carefully aligns the second layer, passes it through the laminator once more, then coats the opposite side with ink and carries out a second acid bath.
Once the entire process is finished and all layers of ink and toner have been thoroughly cleaned off, Bettina ends up with a PCB that is ready for soldering components—only somewhat dirty from the ink. As for what this board will specifically be used for, she deliberately left a cliffhanger, saying it would be revealed in the next video. Her projects usually revolve around designs from old electronics magazines, so it is almost certainly that kind of thing—and that is also why this board cannot simply be handed off to a prototyping fab.