Point Contact 1947 Attach a Base Lead and Support the Germanium Mechanically
# Attach a Base Lead and Support the Germanium Mechanically: A Mount That Has to Be Stiffer Than a Spring It Hasn't Met Yet
This step does two jobs at once — wiring the base metal layer out to a usable terminal, and giving the germanium a mechanical anchor — but the mechanical half of that job has a requirement this sequence hasn't needed until now: this mount has to be rigid enough to withstand a spring force that won't actually exist until step fifteen presses two point contacts against the opposite face. A mount that flexes under that future load doesn't just risk cracking the germanium — it silently steals deflection from the spring mechanism that will eventually hold the point contacts in place, which means this step's mechanical design decision has real consequences for a step almost ten operations away.
## 1. A Compliant Mount Competes With the Spring for the Same Deflection
Later in this sequence, a spring presses the point contacts against the germanium with a force set by the spring's own stiffness $k_{\text{spring}}$ times how far it's compressed — but that force only reaches the germanium cleanly if everything it's pressing against is effectively rigid in comparison. If this mount's own stiffness $k_{\text{mount}}$ isn't comfortably larger than the spring's, the mount itself absorbs part of the intended compression, acting like an unplanned second spring in the same mechanical path, and the actual force delivered to the point contacts ends up lower and less predictable than the spring mechanism alone would suggest.
## 2. Real Diagram: A Rigid Mount Delivers the Spring's Full Intended Force
## 3. The Lead Attachment Can Quietly Undo Step Five's Careful Resistance Work
Step five deliberately maximized the base electrode's contact area specifically to drive spreading resistance down to a small, well-controlled value — but that effort is only worth as much as the weakest link in the full electrical path out to a usable terminal, and this step's lead attachment is the next link in that same chain. A hastily soldered or poorly bonded lead can add a resistance comparable to or larger than everything step five's careful area-maximizing work achieved, which would make the broad electrode's own design effort essentially pointless from an electrical standpoint, even though the mechanical structure underneath it is exactly as intended.
## Attach a Base Lead and Support the Germanium Mechanically's Place in the Process Lineage
Attaching a base lead and supporting the germanium mechanically is step six of the twenty-five-step sequence documenting the original 1947/48 Bell Labs point-contact transistor — immediately after copper or gold was applied to the underside, and before any surface treatment of the opposite face begins. It is the step that establishes the device's physical mounting well before the mechanism it has to support mechanically — the spring-loaded point contacts of step fifteen — even exists, and it completes the base connection's electrical path by adding a lead resistance that has to stay small relative to the spreading resistance step five already worked to minimize. Step seven, re-etching the exposed upper face if the metallization contaminated it, is the first step to work directly on the face this mount now holds steady.