IPC4761 via type ---Filled & Covered Via
Some customers always asked us about IPC4761 VII via type .
"Vias Stuffed: YES, with conductive material according to IPC-4761 type VII, then tented with soldermask." Here is an example from Customer's requirement.Let's take this sentence apart to analyze it。
Via Stuffed:Yes. correct.
With conductive material according to IPC-4761 Type VII. NO.
There are some types in IPC-4761. See below
Tended (Via Type I-a/-b) and Tented and covered (Via type II-a/-b) A via with a dry film mask material applied bridging over the via wherein no additional materials are in the hole. Via type II is Via type I with an additional cover. Prior to surface finish.
Plugged (Via Type III-a/-b) A via or through hole with material applied allowing partial penetration into the via or through hole. The plug material may be applied from either one or both sides of the via structure. (Prior to surface finish.)
Plugging and covered (Via Type IV-a/-b) : A via or through hole with a secondary covering of mask material applied over the plugged via. The material may be applied from either one or both sides of the via structure. (Prior to surface finish.)
Filled (Via Type V) : A via or through hole with material applied into the via or through hole targeting a full penetration and encapsulation of the hole. (Prior to surface finish.)
Filled and covered (Via Type VI) : A via or through hole with a secondary covering of material applied over the filled via or through hole. The material may be applied from either one or both sides of the via structure. (Prior to surface finish.)
Filled and capped (Via Type VII) : A via or through hole with a secondary metallized coating covering the via or through hole. The material may be applied from either one or both sides of the via structure. (Prior to surface finish.)
The summary is as follows。
| Type | Description | Covering-Material |
|---|---|---|
| I-a / -b | Tented one-sided / double-sided | Dryfilm solder-stop |
| II-a / -b | Tented & Covered one-sided / double-sided | Dryfilm solder-stop + LPI solder-stop |
| III-a / -b | Plugged one-sided / double-sided | Plugging Epoxy (non-conducting paste) |
| IV-a / -b | Plugged & Covered one-sided / double-sided | Plugging Epoxy + LPI solder-stop |
| V | Filled | Plugging Epoxy (non-conducting paste) |
| VI-a / -b | Filled & Covered one-sided / double-sided | Plugging Epoxy + LPI solder-stop |
| VII | Filled & Capped |
Special Plugging Epoxy + plating |
When we say "Via in pad" or "POFV--Plated over for vias",we will make the vias according IPC-4761 VII with filled and capped .Also, blind will be made in this way too. The via is plated-through and cleaned - afterwards a non-conductive paste is forced in and hardened - the ends are planarized, metallized and plated-over. Hence, the surface is planar and solderable.
From the above information ,we can know the filling material is not conductive , it is non-conductive, it is resin ,just plated and capped ,that makes metallized.so many customers misunderstand the filling material is conductive.
