The engineering communication for this 8-layer HDI board records specific conditions found in the hole data and the corresponding treatments or confirmation requests. HDI stage count is listed as 2 and blind and buried holes are marked yes. The notes focus on whether indicated and illustrated holes are to be fabricated as plated or non-plated, based on the plated or non-plated requirements stated for them and on the pad and annular-ring conditions present in the layer artwork.
8-Layer HDI PCB: Plated Holes with Undersized Pads
The board ( #HDI-20251018-0141 ) CAM review that holes indicated by arrows are required to be made as plated holes, yet the pads on the circuit layers are smaller than the drill. For these holes the factory records that it will treat them as non-plated holes.
The statement identifies two elements present in the data for the indicated holes: the requirement that the holes be plated, and the size relationship in which the pads appearing on the circuit layers are smaller than the drill diameter. It then records the fabrication treatment that will be applied to those holes, which is non-plated construction.
No additional description of the pad diameters, the exact drill size, or the number of such holes is included in the note. The recorded content is limited to the plated requirement, the undersized-pad condition relative to the drill, and the decision to fabricate the holes as non-plated.
HDI Plated Holes with Missing Annular Rings on One Outer Layer
The communication states that the illustrated holes are required to be made as plated holes, but on the two outer-layer circuits one side has an annular ring while the other side has no annular ring. For this type of hole the factory states that it is difficult to judge whether the holes should be treated as non-plated. The note adds that some of the holes have network connections on the inner layers. It further states that if the holes are to be made as non-plated, pads larger than the hole by 0.3 mm on each side must be added and windows must be opened normally. Confirmation is requested on how the hole attributes are to be made.
Figure 1, 2: On the two outer layers, one side has an annular ring while the other side does not
The same portion of the communication then sets out the suggestion in two alternatives. The first alternative is to treat the holes as non-plated, applying normal copper clearance on both the inner layers and the outer layers. The second alternative is to treat the holes as plated by adding an annular ring of 0.3 mm on each side and opening the windows normally.
These sentences therefore contain the plated-hole requirement for the illustrated holes, the observation that an annular ring exists on only one of the two outer layers, the statement that judgment of non-plated treatment is difficult, the presence of inner-layer network connections on some of the holes, the conditional requirement to add 0.3 mm pads per side and open windows normally if non-plated fabrication is chosen, the request for confirmation of the hole attributes, and the two explicit treatment options placed in the suggestion.
The 0.3 mm dimension appears only in connection with the pad or annular-ring addition. It is stated once as the amount by which pads must be larger than the hole on each side if non-plated treatment is selected, and once as the annular-ring width to be added on each side if plated treatment is selected. No other clearance or pad-size values are given for these holes in the note.
Non-Plated HDI Holes with Pads on the Top Layer
The communication states that holes indicated by arrows are required to be made as non-plated holes, yet the top-layer circuitry has pads. The factory records that it will treat these holes as non-plated and asks for confirmation whether this is acceptable.
The statement identifies the non-plated requirement given for the indicated holes and the presence of pads in the top-layer circuitry at those locations. It then records the treatment to be applied, which is non-plated fabrication, together with the request that the customer confirm whether the treatment is acceptable.
No further detail is supplied concerning the size of the top-layer pads, their relationship to the drill, or the presence or absence of pads on the bottom layer. The recorded content consists of the non-plated requirement, the existence of top-layer pads, the planned non-plated treatment, and the confirmation request.
Figure 3, 4: The hole indicated by the arrow will be made as a non-plated hole.
HDI PCB Hole Attribute Review and Manufacturing Options
The engineering communication addresses hole attributes for the 8-layer HDI board through three distinct observations. In the first, holes indicated by arrows carry a plated-hole requirement while the pads on the circuit layers are smaller than the drill; the recorded treatment is non-plated fabrication. In the second, illustrated holes carry a plated-hole requirement while an annular ring is present on only one of the two outer layers; the factory states that it is difficult to judge non-plated treatment, notes that some holes have inner-layer network connections, and states that non-plated fabrication would require pads 0.3 mm larger per side with normal window opening. Confirmation of the attributes is requested, and the suggestion offers either non-plated treatment with normal copper clearance on inner and outer layers or plated treatment with 0.3 mm annular rings added per side and normal window opening. In the third, holes indicated by arrows carry a non-plated requirement while pads exist on the top-layer circuitry; the recorded treatment is non-plated fabrication, accompanied by a request for confirmation.
Each observation begins from the plated or non-plated requirement stated for the holes in question and then records the pad or annular-ring condition found in the corresponding layer data. The treatments or the confirmation requests follow directly from those conditions. For the holes that have an annular ring on only one outer layer, the communication additionally records the inner-layer network connections on some holes and places the 0.3 mm pad or ring dimension inside both the conditional non-plated path and the plated alternative of the suggestion.
The three sets of statements constitute the hole-attribute portion of the engineering communication. They identify the requirements given for the indicated and illustrated holes, the mismatches between those requirements and the pads or annular rings present in the artwork, and the non-plated treatments or the confirmation-and-suggestion language recorded in response.
