Thanks for your interest in our very first PCB design Ask Me Anything!
Click the link below to register!
Already registered? I’ll send you the Zoom link by email in a few minutes. In the meantime, you can start posting your questions in this thread.
Hello,
I have a few questions on manufacturability of PCBs.
- Your soldermask comes in various colors, but the colors drop down when you reach advanced boards. Is this due to the soldermask itself having impacts to the manufacturability or performance, or is it just that certain colors are easier to inspect at higher standards?
- Acid traps in manufacturing. There are IPC standards that advise against angled entry to pads to avoid acid traps. However, I have seen a good bit of hobbyist and large-scale electronics company boards that don’t seem to take that into account during their layout process. How much of a concern are acid traps in your manufacturing process?
- Likewise, teardropping vias. Do you recommend them for board designers on low-speed circuits?
- What are best practices you recommend to improve manufacturability of the design, or to generally bring down cost?
1 Like
Our R&D engineer will reply but you should definitely register for our AMA next Friday.
-
Typically advanced boards have small features and green solder mask has the best resolution. The other colors, especially black, are more difficult to expose and won’t hold the same line resolution as green.
-
Acid traps typically aren’t a problem. Advancements in process equipment and chemistries have pretty much taken care of the problem.
-
Teardropping is always a good idea but how much they help is design dependent.
-
This really depends on the design but keeping things as simple as possible usually helps.
Hello Lucy,
What are the rules for the high-voltage minimum conductor spacing in rigid-flex PCB when the flex PCB is continuously moving?
Is the IPC-2221B internal conductor (B1) acceptable or we need to use other rules.
Is the delamination of the flex PCB layer a concern?
Are the copper traces manufacturing tolerance included in the rules?
I notice that other manufacturer recommends using the IPC-2221B (B4) External Conductors, with permanent polymer coating (at any elevation) plus 2mil.
Thank you.
1 Like
Thanks for sending those questions. Greg will reply live on Friday. Will you be able to join?
Hi Lucy,
Thank you. I will join the webinar on Friday.
Regards,
Mihail
1 Like
Cool, see you there! And check out this thread early next week, I’ll post the answers to your questions from today’s webinar: Webinar: Aerospace PCB Design Challenges and Techniques to Fix Them
Thx for joining!
I have some questions about cavities for a few different applications.
-
We are designing an open step-down cavity that requires embedded component placement on the floor of the cavity, but we also require the vertical walls to be copper-plated for environmental/moisture isolation.
-
Would this be an IPC-6012F type 3 cavity?
-
What is the minimum spacing or clearance required between the inner edge of the plated vertical wall and the nearest etched component pad on the cavity floor?
-
-
We are designing a multi-layer board utilizing large, completely air-filled embedded cavities for a similar stackup to a cavity backed antenna application or a Substrate Integrated Cavity/Waveguide (SIC / SIW) application. To prevent resin flooding into these pockets during lamination, we are evaluating stackup bonding methods.
-
What is the maximum horizontal span/area limit for an empty pocket when using the pre-cut, low/no-flow prepreg window technique before the top/bottom layers suffer from structural z-axis sagging or collapse during lamination?
-
If our target cavity dimensions exceed this structural limit, do you support a sacrificial insert (insert-and-remove) technique to hold the internal structural volume during the lamination press?
-
To flush out the sacrificial material post-lamination, what are your design rules for ventilation/exhaust ports?
-
-
We need to selectively deposit a conductive carbon film over select pads.
-
Can your facility deposit conductive carbon ink inside a recessed step-down cavity?
-
Are you limited to flat screen-printing for carbon ink, or do you support robotic Z-axis dispensing/inkjetting to reach the floor of a milled pocket?
-
If we need to use screen-printed carbon ink, could we create the step down cavity by first depositing the carbon on the desired layer, then laminating precut low flow prepreg to build the rest of the PCB stack?
-
Could we create carbon coated pads inside internal Air-Filled Substrate Integrated Waveguide (AFSIW) cavities? What sacrificial material could be used during lamination that wouldn’t damage the carbon film?
-
-
In the step-down open cavity, for environmental insulation, we want the solder mask to run continuously from the top surface, down the vertical walls, and across the cavity floor. Is this possible? Note: conformal coating/potting/parylene isn’t feasible in this instance.
-
Can your shop support Electrostatic Spray Solder Mask or Dry Film Solder Mask to ensure uniform coverage on 3D vertical steps without pooling?
-
What is the maximum depth-to-width aspect ratio of the cavity that can be achieved without tearing the mask?
-
What is the minimum radius of curvature needed for the solder mask in the cavity corners? Larger than the ~0.4mm required by standard milling of the cavity?
-
Will some chamfer and fillet need to be applied to the z-axis edges of the cavity, between the horizontal and vertical transitions?
-
What is the targeted cured thickness of the solder mask on the vertical walls versus the cavity floor?
-
How do you inspect and verify solder mask continuity and thickness inside a 3D cavity to ensure no micro-voids or bubbles?
-
What is the positional registration tolerance for the solder mask imaging on the cavity floor so we can calculate our pad clearances?
-
Thanks!
1 Like
You can watch the recording here: