Tefillin Chol HaMoed Hefsek

Question

Although it's forbidden to make an interruption between putting on the tefilin shel yad and shel rosh (Shulchan Aruch 25:9)

אסור להפסיק בדיבור בין תפלה של יד לתפל' של ראש ואם הפסיק מברך על של ראש על מצות תפילין: הגה ולדידן דנוהגין לברך ב' ברכות אף אם לא הפסיק צריך לחזור ולברך על של ראש להניח וגם על מצות - It is forbidden to speak at all between putting on the two tefillin, and if he spoke, he must make the blessing on the head tefillin. Note: Since we [Ashkenazim] make two blessings, he must make both blessings on the head tefillin

since my minhag is to put on tefillin without a bracha on Chol haMoed, would I be able to make a hefsek between the tefillin shel yad and shel rosh? (By answering kaddish)

Answer 1

The Mishnah Berurah there explicitly addresses your question. In s.k. 28 he writes:

ואפילו לאותן המניחין תפילין בחוה"מ בלי ברכה או המניחין תפלין דר"ת אחר שחלץ תפלין דרש"י או שחלץ תפלין ע"מ להחזירן דהרמ"א בסי"ב פסק דא"צ לחזור ולברך כשמניחן אח"כ אפ"ה עבירה היא להסיח ביניהן דלכתחילה בעינן שיהיו סמוכין ותכופין זה לזה דכתיב והיה לך לאות על ידך ולזכרון בין עיניך שיהא הוייה אחת לשתיהן

Even those who wear tefillin on Chol HaMoed without a blessing, or those who wear Rabbeinu Tam tefillin after they've already worn Rashi's tefillin, or someone who takes off tefillin with intention to put them back on (which the Rema in Seif 12 rules that one doesn't make another blessing) and puts them on later, even so it is a transgression to speak between them. This is because ideally we need the two tefillin to be connected and adjacent to each other, as it is written: "It shall be for you as a sign on your arm and a remembrance between your eyes", that they should have the same "being" for the two of them.

In Shaar HaTziyun he cites the Magen Avraham (s.k. 14):

ואפי' לאותן המניחין בח"ה בלא ברכה אפי' הכי עבירה היא להסיח (ב"י מהרא"י)‏

Even those who wear tefillin on Chol HaMoed without a blessing, even so it is a transgression to speak.

The Magen Avraham cites the Beis Yosef (ad. loc.) and Terumas HaDeshen (#107) (who the Beis Yosef brings). The Pri Megadim (Mishbetzos Zahav ad. loc. s.k. 4; Eishel Avraham ad. loc. s.k. 17) explains that this concept of having the two tefillin be connected comes from Ba'al HaMeor at the end of Rosh Hashanah. According to him, not only is speaking forbidden, but even answering Amen Yehei Shmeih Rabbah.

However, the Pri Megadim infers from the Shulchan Aruch in Seif 10 that the latter disagrees with the Ba'al HaMeor. Really the issue is unnecessarily causing a new blessing to be said. Therefore, someone who doesn't make a blessing on Chol HaMoed could in fact answer Yehei Shmeih Rabbah. The Magen Avraham (s.k. 17) therefore says that it would be permissible to respond in such a case:

ומ"מ משמע דהמניח בחה"מ בלא ברכה רשאי לענות דליכא איסורא בזה אלא משום שגורם ברכה: ‏

It would seem though the the Magen Avraham holds לכתחילה, ideally, to consider the opinion of the Ba'al HaMeor. That's why he forbade speaking on Chol HaMoed between the tefillin. Indeed, the Mishnah Berurah above explained the reasoning for not interrupting the same as the Ba'al HaMeor.

Therefore, even though the Mishnah Berurah (s.k. 36) rules like this latter Magen Avraham that it's permissible to respond to Amen Yehei Shmeih Rabbah on Chol HaMoed between the tefillin, he says to move the tefillin shel yad from their spot and then put them back before putting on the shel rosh. This way it'll be as if the act of putting on the two tefillin was connected:

ובחוה"מ או המניח תפילין דר"ת וכיוצא שמניח בלי ברכה יש להקל ולהפסיק לעניית איש"ר וקדושה וברכו ואמן אך אח"כ יזיז הש"י ממקומו קודם שיניח הש"ר כדי שיהיה הוייה אחת לשניהן:‏

For some reason though the Magen Avraham and Mishnah Berurah don't want to rely on this solution for trivial interruptions. They only permit these important responses.

Answer 2

In a lecture about wearing tefillin on Chol Hamoed (starting at approximately 8:26 into the recording), R. Aryeh Lebowitz said as follows:

Now if you happen to put on tefillin without a beracha like the shitas haTaz, so the whole thing about not being mafsik between the beracha that you say on the shel yad until after you finish putting on the shel rosh – even for amen yehei shemei rabbah, and amein, and kedushah and barechu – so that won't apply. You would then be allowed to answer for all those things in between the shel yad and the shel rosh. You may need to again adjust the shel yad afterwards to make the connection between the shel yad and the shel rosh but you would be allowed to answer to all those things.

His point seems to be that even if there needs to be a connection between the shel yad and the shel rosh, the connection can be established after the interruption. Normally this can't be done because it would be an interruption between the beracha and the mitzvah, but in this case that issue is moot.